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The influence of electronic effects on the enantioselectivity of the oxazaborolidine-catalyzed asymmetric borane reduction of ketones has been observed and investigated with use of parasubstituted acetophenones and propiophenones with a variety of functional groups and B-unsubstituted and B-methoxyoxazaborolidines derived from (S)-2-(diphenylhydroxymethyl)-pyrrolidine with borane and trimethyl borate as catalysts in toluene and THF. The results indicate that Hammett linear free energy electronic effects on the enantioselectivity in the asymmetric reduction were observed and rationalized. Tuning electronic effects of the catalyst can improve the enantioselectivity in the reduction. Another interesting finding to be noted is that anions heavily affect the enantioselectivity, especially for the B-methoxy catalyst, because of their coordination with the boron atom in the catalysts. https://www.lookchem.com/CASDataBase_101219-73-2.htm

The photochemistry, in methanol, of substituted 2,2-dimethyl-1-indanyl acetates 9a-c and pivalates 10a-c has been studied.In agreement with previous studies on benzylic esters, the results show that the substituents change the yield of products derived from the ion pair.The mechanistic conclusion reached is that the substituents change the oxidation potential of the indanyl radicals and thus the rate constant of electron transfer for converting the radical pair to the ion pair.The results also reveal two other substituent effects.First, substituents can increase the overall efficiency of the photoreaction by enhancing homolytic cleavage.The second effect is conformational.In compounds where the bond that is cleaving is conformationally mobile, such as the C-O bond in benzylic esters, substituents on the ring can change the population of the reactive conformer and thus the overall efficiency of the reaction.For the indanyl acetate esters, the difference in excited-state reaction rate be

Reaction of LiGaH4 and gallium metal with 1,4-di-t-butyl-1,4-diazabutadiene (dbdab) in diethyl ether at room temperature yields the monomeric, formally gallium(II) species , (1), previously prepared using metal vapours, and GaH3*NMe3 with dbdab in hexane at -80 deg C yields the novel hydrogallation product < 2 t )CH2>2>, (2) which has magnetically distinct geminal hydrides ( 2 J HH 44 Hz) in agreement with the crystal structure ( 2.01 3 Angstroem, 1.5 6 Angstroem) and IR data (νGa-H 1920, 1870 cm -1 ). https://www.lookchem.com/CASDataBase_7440-55-3.htm

The synthetic utility of cerium(IV) triflate Ce(OTf) 4 as a reagent for benzylic oxidation has been tested for a variety of aromatic compounds. Insight is provided into various factors that govern these oxidations and their progress. It has been shown that the mode of preparation of Ce(OTf) 4 and the % H 2 O present in the sample have a marked influence on oxidation ability. A variety of mono- and dialkylbenzenes, haloalkylbenzenes, bicyclic and tricyclic ring systems, and alkoxybenzenes have been surveyed. The method offers an easy to perform one-pot reaction for the room temperature synthesis of aromatic ketones and aldehydes from aromatics and has the potential to find wider application. https://www.lookchem.com/CASDataBase_1009-61-6.htm

The crystal structures of racemic and (2S,3R)-(-)-3-hydroxy-2-(4-methoxyphenyl)-2,3-dihydro-1,5-benzothiazepin-4(5H)- one (C 16 H 15 NO 3 S) have been determined in order to compare the interactions between molecules of the same and opposite chirality. The enantiomeric associations observed in these two crystal structures are analysed, relating the differences to those found in the equivalent diastereomers, (2R, 3R) and/or (2S, 3S). Single-crystal X-ray diffraction data were collected at low temperature with Cu Kα radiation (λ = 1.54184 A). Optically active: monoclinic, space group C2, with a = 24.726(3), b = 5.2426(5), c =12.0726(12) A, β - 112.979(9)°, V = 1440.8(5) A 3 , Z = 4, D x = 1.389 g cm -3 , μ = 20.35 cm-1, the refinement on 2918 observed reflections gave R=0.0271. Racemic: monoclinic, space group P2 1 /n, with a = 13.308(3), b = 4.8474(8), c = 22.130(4) A, β = 91.782(14), V= 1426.9(5) A 3 , Z=4, D x = 1.403 g cm -3 , μ= 20.54 cm -1 , refined to R = 0.0318 for 2753 observed

N-Unprotected ketimines are useful substrates and intermediates for synthesizing valuable nitrogen-containing compounds, but their potential applicability is limited by the available synthetic methods. To address this issue, we report a scandium(III) triflate catalyzed direct synthesis of N-unprotected ketimines. Using commercially available reagents and Lewis acid catalysts, ketones were directly transformed into the corresponding N-unprotected ketimines in high yields with broad functional group tolerance, even in multigram scales. The reactions were readily applicable for one-pot synthesis of important compounds such as a glycine Schiff base without isolation of N-unprotected ketimine intermediates. Preliminary mechanistic studies to clarify the reaction mechanism are also described. https://www.lookchem.com/CASDataBase_1013-88-3.htm

Acid-free Friedel-Crafts chemistry: A paradox? Nucleophilicity scales, based on reactions with benzhydrylium ions, show that many π systems are more nucleophilic than aqueous or alcoholic solutions that are generally employed as solvents for S N 1 reactions. Solvolytically generated carbocations can, therefore, be trapped by donor-substituted arenes and alkenes to form products of Friedel-Crafts-type reactions in neutral aqueous solutions (see scheme). https://www.lookchem.com/CASDataBase_726-18-1.htm

(2R,3R)- and (2S,3S)-3-Hydroxyleucines, components of cyclodepsipeptides, papuamides and polyoxypeptins, were efficiently synthesized along with their diastereomers from the corresponding β-keto-α-amino acid ester through dynamic kinetic resolution using RuCl 2 (binap)-catalyzed hydrogenation. https://www.lookchem.com/CASDataBase_10148-70-6.htm

The catalytic transposition of double bonds holds promise as an ideal route to alkenes of value as fragrances, commodity chemicals, and pharmaceuticals; yet, selective access to specific isomers is a challenge, normally requiring independent development of different catalysts for different products. In this work, a single cation-responsive iridium catalyst selectively produces either of two different internal alkene isomers. In the absence of salts, a single positional isomerization of 1-butene derivatives furnishes 2-alkenes with exceptional regioselectivity and stereoselectivity. The same catalyst, in the presence of Na + , mediates two positional isomerizations to produce 3-alkenes. The synthesis of new iridium pincer-crown ether catalysts based on an aza-18-crown-6 ether proved instrumental in achieving cation-controlled selectivity. Experimental and computational studies guided the development of a mechanistic model that explains the observed selectivity for various functionalized

The title cyclopentenone has been prepared by enzymatic resolution of cis-4-phenyloxy- and cis-4-(4-methoxyphenyloxy)-cyclopent-2-en-1-ol in isopropenyl acetate using Pseudomonas cepacia lipase. The use of a 4-methoxyphenyloxy-alcohol intermediate enabled the use of both enzymatically resolved enantiomers in the synthesis of the desired (+)-enone. https://www.lookchem.com/CASDataBase_104010-72-2.htm

The possibility to synthesize biologically important sugars and other chiral compounds without any initiators in the UV-initiated reaction of formaldehyde in aqueous solution has been shown for the first time. An optically active condensed phase due to an sp 3 -hybridized carbon atom has been detected. It has been shown that this phase is formed due to the spatial cleavage of antipodes in the racemate, similar to the cleavage of enantiomers following the sign of chirality in the known experiments of Pasteur. The results have been obtained under the conditions that correspond to modern ideas about the form and vector of prebiological evolution and, therefore, can be of fundamental importance for understanding the processes of biopoiesis. https://www.lookchem.com/CASDataBase_10030-80-5.htm

(Matrix presented) A new total synthesis of macrosphelides A and B using ring-closing metathesis (RCM) as a macrocyclization step is described. The substrate of the RCM could be synthesized from readily available chiral materials, methyl (S)-(+)-3-hydroxybutyrate and methyl (S)-(-)-lactate, with a high efficiency. The RCM proceeded in the presence of Grubbs' Ru-complex, providing a new effective synthetic route to these natural products. https://www.lookchem.com/CASDataBase_172923-77-2.htm

We report an iron-catalyzed general functional group protection method with inexpensive reagents. This environmentally benign process does not use acids or bases, and does not produce waste products. Further purification beyond filtration and evaporation is, in most cases, unnecessary. Free COOH and OH groups can be protected in a one-pot reaction. https://www.lookchem.com/CASDataBase_103-45-7.htm

A general and novel solution to the synthesis of biologically important stable analogues of prostacyclin PGI 2 , namely benzindene prostacyclins, has been achieved via the stereoselective intramolecular Pauson-Khand cyclization (PKC). This work illustrates for the first time the synthetic utility and reliability of the asymmetric PKC route for synthesis and subsequent manufacture of a complex drug substance on a multikilogram scale. The synthetic route surmounts issues of individual step stereoselectivity and scalability. The key step in the synthesis involves efficient stereoselection effected in the PKC of a benzoenyne under the agency of the benzylic OTBDMS group, which serves as a temporary stereodirecting group that is conveniently removed via benzylic hydrogenolysis concomitantly with the catalytic hydrogenation of the enone PKC product. Thus the benzylic chiral center dictates the subsequent stereochemistry of the stereogenic centers at three carbon atoms (C 3a , C 9a , and C 1

A commercially available perfluorooctyl aniline and phenyl isothiocyanate were reacted under mild conditions to give 1-[4-(perfluorooctyl)phenyl]-3- phenylthiourea as an analogue of thiourea-based organocatalyst. This fluorous organocatalyst was successfully employed to direct reductive amination of aldehydes. It could be readily separated from reaction product by fluorous solid phase extraction for direct use. https://www.lookchem.com/CASDataBase_17377-95-6.htm

In this study, preparation of highly stable palladium nanoparticles (Pd NPs) on Schiff base modified β-cyclodextrin (β-CD-Sch) in the absence of reducing agents has been successfully carried out. Pd NPs&at;β-CD-Sch has then been applied as nanocatalyst in the synthesis of benzonitriles via cyanation reaction using K 4 Fe(CN) 6 , which is a low cost, commercially available and non-toxic cyanide source. A series of benzonitriles containing different substrates were successfully fabricated with 77–98percent yields using Pd NPs&at;β-CD-Sch. Moreover, Pd NPs&at;β-CD-Sch catalyst was quantitatively recovered and reutilized several times, showing good reaction yields. This work revealed that i) prepared β-CD-Sch is an effective stabilizer for the fabrication of Pd NPs and ii) Pd NPs&at;β-CD-Sch catalyst play an important role in the fabrication of benzonitriles. https://www.lookchem.com/CASDataBase_4210-32-6.htm

Flash vacuum pyrolysis (FVP) of sulfoxides containing β-hydrogen atoms affords sulfenic acids (RSOH) in good concentration under conditions where they are stable.The application of this technique to the synthesis and study of sterically hindered sulfenic acids 12a-e is described.The principal or primary reaction of simple sulfenic acids prepared in this manner is dehydration to thiosulfinates 13 (eq 1).Steric inhibition to dehydration (eq 1) appears to only be of importance for 2-methyl-2-propanesulfenic acid (12a) which was trapped in good yield with methyl propiolate to afford 16a. 2,4,6-Tri-tert-butylbenzenesulfenic acid (12e) appears to be destabilized as a consequence of interaction between the SOH and adjacent tert-butyl groups.In the pyrolysis section of the apparatus, 12e decomposes to phenol 21 and aryl radical 22, which reacts further.Thermolysis of sulfoxides generates the sulfenic acids 12a-e in very low concentration at any one time.The products of sulfenic acids generated

The application of a triazole-substituted chiral iodoarene in a direct enantioselective hydroxylation of alkyl arenes is reported. This method allows the rapid synthesis of chiral benzyl alcohols in high yields and stereocontrol, despite its nontemplated nature. In a cascade activation consisting of an initial irradiation-induced radical C-H-bromination and a consecutive enantioconvergent hydroxylation, the iodoarene catalyst has a dual role. It initiates the radical bromination in its oxidized state through an in-situ-formed bromoiodane and in the second, Cu-catalyzed step, it acts as a chiral ligand. This work demonstrates the ability of a chiral aryl iodide catalyst acting both as an oxidant and as a chiral ligand in a highly enantioselective C-H-activating transformation. Furthermore, this concept presents an enantioconvergent hydroxylation with high selectivity using a synthetic catalyst. https://www.lookchem.com/CASDataBase_4187-87-5.htm

An experimental and theoretical study of the absolute value of the one-bond spin-spin coupling constant | 1 J(Si,H)| in SiH n Cl 4-n (n = 0-4) dissolved in THF-d 8 is presented. We found | 1 J(Si,H)| to incr https://www.lookchem.com/CASDataBase_10025-78-2.htm

An efficient and environmentally friendly synthetic method for the synthesis of primary amides under microwave irradiation was described, in which the primary amine was directly reacted with acid without any catalytic agents. The reaction took place in 8-12-min, which was much shorter than the traditional synthetic methods, with almost quantitative yields. The influential factor of the reaction was discussed. The tautomerization between the carboxylic acid group and the H atom in α-carbon of L-amino acid was observed, presumably a dehydrated intermediate forming from this tautomerized isomer. Copyright Taylor & Francis Group, LLC. https://www.lookchem.com/CASDataBase_104-04-1.htm

The chemical lithiation/delithiation of K + -β-ferrite has been performed using butyllithium, lithium naphthalide (for lithiation), and iodine (for delithiation). In lithiation using butyllithium, the lithium content (y) in K 1+x Li y Fe 11 O I7 was dependent on the average grain size of K + -β-ferrite single crystals; small grains (5 μm) largely reacted with lithium to form K 0 .99Li 1.65 Fe 11 O 17 . Lithiation was performed by the reduction of Fe 3+ to Fe 2+ . Since the same X-ray diffraction (XRD) patterns were obtained before and after lithiation, the reaction seemed to be restricted to only near the grain surfaces. In lithiation using lithium naphthalide, the lithium content (y), which attained to be 36, was independent of the average grain size of K + -β-ferrite single crystals. This lithium content was remarkably large, compared to y = ca. 1.6 in lithiation using butyllithium. A large amount of Fe° (metal) was detected in the samples. According to scanning electron microscope

Arylhydroxamic acid N,O-acyltransferase (AHAT) is an enzyme system that is capable of converting many N-arylhydroxamic acids into reactive electrophilic species. As part of an investigation into the influence of the structure of the aryl group upon the ability of N-arylhydroxamic acids to serve as substrates for AHAT, a series of N-hydroxy-N-(4-alkyl-, 4-alkenyl-, and 4-cyclohexylphenyl) acetamides was prepared and evaluated in vitro with partially purified rat and hamster hepatic AHAT. The nature of the 4-substituent markedly influenced the ability of the hydroxamic acids to serve as acetyl donors in the AHAT-catalyzed transacetylation of 4-aminoazobenzene (AAB). As the length of the 4-substituent was increased from methyl to pentyl, the compounds became increasingly more effective substrates. The compounds containing vinyl, propenyl, and 2-methylpropenyl 4-substituents were more effective acetyl donors than the corresponding compounds containing saturated 4-substituents. The three mo

Using the laser photolysis/laser-induced fluorescence (LIF) "pump-and-probe" technique, the dynamics of H atom formation in the photodissociation of CH 3 -CF 2 Cl (HCFC-142b) after excitation at 193 nm and the Lyman-α wavelength were studied under collision-free conditions in the gas-phase at room temperature. The H atoms produced were detected by (2p 2 P←1s 2 S)-LIF using tunable narrow-band Lyman-α laser radiation (λ Lα ≈ 121.6 nm) generated by resonant third-order sum-difference frequency conversion of pulsed dye laser radiation. In the VUV photodissociation experiments the Lyman-α laser radiation was used both to photodissociate the parent molecules and to detect the produced nascent H atoms via laser induced fluorescence. The following quantum yields Φ H for H atom formation were determined by a photolytic calibration method: Φ H (193 nm) = (0.06±0.02) and Φ H (L α ) = (0.53±0.12). From the measured H atom Doppler profiles the average H atom kinetic energy was determin

Water is found able to determine the selectivity of Br?nsted acid-catalyzed C-O cleavage reactions of trialkyl phosphites: with water, the reaction quickly takes place at room temperature to afford quantitative yields of H-phosphonates; without water, the reaction selectively affords alkylphosphonates in high yields, providing a novel halide-free alternative to the famous Michaelis-Arbuzov reaction. This method is general as it can be readily extended to phosphonites and phosphinites and a large scale reaction with much lower loading of the catalyst, enabling a simple, efficient, and practical preparation of the corresponding organophosphorus compounds. Experimental findings in control reactions and substrate extension as well as preliminary theoretical calculation of the possible transition states all suggest that the monomolecular mechanism is preferred. https://www.lookchem.com/CASDataBase_756-79-6.htm

Crucigasterins 277, 275, and 225, three new polyunsaturated amino alcohols, 10-12, were isolated from the Mediterranean tunicate Pseudodistoma crucigaster.The structures of these compounds were assigned based on NMR and FABMS data.Absolute stereochemistry of the amino alcohol portion in 10 was assigned to be 2R,3S based on chiral GC comparison of 3-hydroxy-4-aminopentanoic acid 13d, a chemical degradation product of 10, with a synthetic sample prepared from L-alanine.Compounds 10-12 exhibited moderate cytotoxicity and antimicrobial activity. https://www.lookchem.com/CASDataBase_10065-72-2.htm

We report the first copper-catalyzed/mediated borylative ring opening reaction of epoxides. This process represents a direct borylative C(sp 3 )-O bond cleavage of terminal epoxide substrates with commercially available diboron reagents. A wide range of epoxides with different functional groups are involved, and were subsequently converted to the corresponding β-hydroxyl boronic esters smoothly. Moreover, the ring opening product β-pinacol boronate alcohol provided a more beneficial approach for the formation of C-C and C-N bonds. https://www.lookchem.com/CASDataBase_17325-85-8.htm

Novel nitrogen-bridged diazocines (triazocines) were synthesized that carry a formyl or an acetyl group at the CH 2 NR-bridge and bromo- or iodo-substituents at the distant phenyl ring. The photophysical properties were investigated in acetonitrile and water. As compared to previous approaches the yields of the intramolecular azo cyclizations were increased (from ≈40 to 60%) using an oxidative approach starting from the corresponding aniline precursors. The Z→E photoconversion yields in acetonitrile are 80–85% and the thermal half-lives of the metastable E configurations are 31–74 min. Particularly, the high photoconversion yields (≈70%) of the water-soluble diazocines are noteworthy, which makes them promising candidates for applications in photopharmacology. The halogen substituents allow further functionalization via cross-coupling reactions. https://www.lookchem.com/CASDataBase_75-87-6.htm

The transposition of Sandmeyer chlorination from a batch to a safe continuous-flow process was investigated. Our initial approach was to develop a cascade method using flow chemistry which involved the generation of a diazonium salt and its quenching with copper chloride. To achieve this safe continuous process diazotation, a chemometric approach (Simplex method) was used and extrapolated to establish a fully continuous-flow method. The reaction scope was also examined via the synthesis of several (het)aryl chlorides. Validation and scale-up of the process were also performed. A higher productivity was obtained with increased safety. https://www.lookchem.com/CASDataBase_7335-27-5.htm

The enantioselective total synthesis of (?)-tetrodotoxin [(?)-TTX] and 4,9-anhydrotetrodotoxin, which are selective blockers of voltage-gated sodium channels, was accomplished from the commercially available p-benzoquinone. This synthesis was based on efficient stereocontrol of the six contiguous stereogenic centers on the core cyclohexane ring through Ogasawara's method, [3,3]-sigmatropic rearrangement of an allylic cyanate, and intramolecular 1,3-dipolar cycloaddition of a nitrile oxide. Our synthetic route was applied to the synthesis of the tetrodotoxin congeners 11-norTTX-6(R)-ol and 4,9-anhydro-11-norTTX-6(R)-ol through late-stage modification of the common intermediate. Neutral deprotection at the final step enabled easy purification of tetrodotoxin and 11-norTTX-6(R)-ol without competing dehydration to their 4,9-anhydro forms. https://www.lookchem.com/CASDataBase_4368-28-9.htm

Several strategies for the development of the synthesis of P-chiral organophosphorus compounds with (L)-prolinol as a source of chirality have been examined. A reaction of L-prolinol with a set of different alkyl/arylphosphonous acid diamides led in most of the cases to the quantitative formation of the appropriate bicyclic oxazaphospholidines with complete diastereo and enantioselectivity. The latter were reacted with BH 3 complex and the formed borane analogues were submitted to structural modifications leading to tertiary phosphine-boranes. Additionally, the effectiveness of oxazaphospholidines as ligands in transition metal asymmetric catalysis has been tested in hydrogenation of dehydroaminoacid esters and imine. https://www.lookchem.com/CASDataBase_17480-69-2.htm

Sodium hypophosphite has been used as an efficient hydrogen donor in the transfer hydrogenation of aliphatic and aromatic ketones in the presence of [RuCl 2 (p-cymene)] 2 and 2,2′-bipyridine in water. The corresponding alcohols were isolated in moderate to excellent yields (39-95 %). Good chemoselectivity was observed with ester, nitrile and halide functionalities in the ketones not being reduced. An enantioselective version of the reaction using [RuCl(p-cymene){(R,R)-TsDPEN}] as catalyst in a glycerol/2-MeTHF biphasic solvent mixture has been developed and allowed the reduction of (hetero)aromatic ketones with excellent chemo- and enantioselectivities (up to 97 % ee). Sodium hypophosphite has been used in the reduction of ketones in water (nine examples, 40-95 % yield). An original glycerol/2-MeTHF biphasic solvent system has been developed for the enantioselective version of the reaction. This system allows the preparation of aryl alkyl alcohols with up to 97 % ee (22 examples). Cop

Chiral amine catalyst was synthesized using (1R, 2S)-(-)-norephedrine and 5-chlorosalicylaldehyde by reductive amination. The structure of the catalyst was confirmed using 1 H-NMR and 13 C-NMR spectroscopic method. The catalyst was immobilized onto SBA-15 via covalent bonding using 3-chloropropyltrimethoxysilane as a reactive surface modifier under reflux condition using toluene as a solvent. The supported chiral catalyst was characterized using various physico-chemical techniques like XRD, SEM, N 2 adsorption isotherm, FTIR and UV-DRS to study the morphology, pore dimension, functional group analysis and catalyst loading in the mesoporous material. The immobilized catalyst was studied for prochiral ketone reduction using 30 mol% of chiral catalyst and boranedimethylsulphide as a stoichiometric reductant in toluene under inert atmosphere for 30 minutes. Secondary alcohols were formed up to 79% enantiomeric excess for selective ketones. Catalyst was recycled from the reaction mixture a

Dimethyl- and diphenylstannylene (SnMe 2 and SnPh 2 , respectively) have been successfully detected and characterized in solution. The stannylenes were generated by photolysis of 1,1,3-trimethyl-4-phenyl- (2) and 3,4-dimethyl-1,1-diphenylstannacyclopent-3-ene (3), respectively, which have been shown to extrude the species cleanly and in high (0.6 < Φ < 0.8) quantum yields through trapping studies using dichlorodimethylstannane (Me 2 SnCl 2 ) as the stannylene substrate. Laser flash photolysis of 2 and 3 in deoxygenated hexanes affords promptly formed transient absorptions assigned to SnMe 2 (λ max = 500 nm; ε 500 = 1800 ± 600 M -1 cm -1 ) and SnPh 2 (λ max = 290, 505 nm; ε 500 = 2500 ± 600 M -1 cm -1 ), respectively, which decay with absolute second-order rate constants within a factor of 2 of the diffusional limit in both cases. The decay of the stannylenes is accompanied by the growth of new transient absorptions ascribable to the corresponding dimers, the structures o

Acylimidazolium acetate was readily prepared in situ from the reaction of imidazole with acetic anhydride and subsequently acted as a catalyst and acylating agent for the efficient acetylation of alcohols, phenols, and amines at ambient temperature. https://www.lookchem.com/CASDataBase_103-88-8.htm

Several 1-N-substituted derivative [haloacetyl-, glycyl-, (dimethyl)amino-acetyl-, azidoacetyl-, trifluoroacetyl-, and trifluoromethylsulfonyl-] of 2-acetamido-2-deoxy-3,4,6-tri-O-acetyl-beta-D-glucopyranosylamine (1) were synthesized as potential metabolic inhibitors of cellular-membrane glycoconjugates. Several fully acetylated derivatives were found to inhibit growth of mouse mammary adenocarcinoma TA3, leukemia L1210, or leukemia P-288 cells at 1-0.01 mM concentration in vitro. Some of these derivatives were less active after O-deacetylation. Analogs of 1 in which NH2-1 was replaced by OH- or OAc-1 were also active on the same cell systems. The growth-inhibitory activity was correlated with inhibition of the incorporation of 2-amino-deoxy-D-glucose and L-leucine into a macromolecular fraction. https://www.lookchem.com/CASDataBase_10385-50-9.htm

Formal propagation of (hetero)arylamine is achieved via a one-pot Buchwald–Hartwig C–N cross-coupling and nitro reduction sequence, enabling a rapid modular synthesis of diverse amino-di(hetero)arylamines from (hetero)arylamines and halogenated nitrobenzenes. Various functionalized aromatic amines with different electronic and steric environments can be efficiently prolongated to formally incorporate another arylamino fragments. This approach has been successfully applied in the synthesis of more than forty amino-di(hetero)arylamines. The applicability of this method has also been demonstrated in the synthesis of oligoanilines and the tyrosine-kinase inhibitor Imatinib. https://www.lookchem.com/CASDataBase_101-54-2.htm

An efficient and highly enantioselective synthesis of florfenicol- via a new intermediate threo-dihydroxy ester, with a Sharpless asymmetric dihydroxylation as the key step, is reported. A ring-opening/reduction strategy avoids the formation of a chlorinated byproduct that occurs in Schumachers phenyloxazoline procedure. The overall yield of florfenicol by this new process is 23% based on 4-(methylsulfonyl)benzaldehyde. Georg Thieme Verlag Stuttgart · New York. https://www.lookchem.com/CASDataBase_73231-34-2.htm

Taking the 'O': Supported gold and silver nanoparticles (NPs), which are wellknown epoxidation catalysts, were found to have intrinsic catalytic ability for the deoxygenation of epoxides into alkenes using alcohol as a reductant (see picture). The selectivity for all the alkenes were over 99%, and an excellent turnover number was achieved. Furthermore, these supported gold and silver nanoparticles were recyclable. Figure Presented https://www.lookchem.com/CASDataBase_1746-13-0.htm

(Chemical Equation Presented) A catalyst system consisting of a copper-aluminum hydrotalcite-chiral diphosphine ligand effects asymmetric hydrosilylation of several ketones, using polymethylhydrosiloxane (PMHS) as the stoichiometric reducing agent at room temperature, with moderate-to-excellent enantioselectivities. The catalyst is recovered by simple centrifugation, and the efficiency of the catalyst remains almost unaltered even after several cycles. https://www.lookchem.com/CASDataBase_42070-92-8.htm

N,N-Dimethylformamide was found to act as solvent and catalyst in the dehydration of aldoximes to nitriles. The reaction required heating at 135°C and yields of nitriles were moderate to good. (Benzylideneaminooxy)formaldehyde was detected as an intermediate in one of the reactions. Georg Thieme Verlag Stuttgart. https://www.lookchem.com/CASDataBase_1003-31-2.htm

A new and efficient method for the chlorodehydration of alcohols utilizing TCCA/DMF is described. Various alcohols can be converted smoothly into their corresponding alkyl chlorides in high yields under mild conditions with short reaction times. Taylor & Francis Group, LLC. https://www.lookchem.com/CASDataBase_75-29-6.htm

The cytochrome P450 monooxygenase CYP101B1, from a Novosphingobium bacterium is able to bind and oxidise aromatic substrates but at a lower activity and efficiency than norisoprenoids and monoterpenoid esters. Histidine 85 of CYP101B1 aligns with tyrosine 96 of CYP101A1, which, in the latter enzyme forms the only hydrophilic interaction with its substrate, camphor. The histidine residue of CYP101B1 was mutated to phenylalanine with the aim of improving the activity of the enzyme for hydrophobic substrates. The H85F mutant lowered the binding affinity and activity of the enzyme for β-ionone and altered the oxidation selectivity. This variant also showed enhanced affinity and activity towards alkylbenzenes, styrenes and methylnaphthalenes. For example the rate of product formation for acenaphthene oxidation was improved sixfold to 245 nmol per nmol CYP per min. Certain disubstituted naphthalenes and substrates, such as phenylcyclohexane and biphenyls, were oxidised with lower activity by

Rac-α-bromo acids, rac-4, have been converted into(R)- or(S)-α-hydroxy acids, (R)- or (S)-9 by DCC-induced esterification with the chiral auxiliaries (R)or (S)-1, followed by reaction with sodium p-methoxyphenoxide in the presence of tetra-n-hexylammonium iodide, conditions of dynamic kinetic resolution, to give quite diastereoselectively the (αR,3S)- or (αS,3R)-α-(p-methoxyphenoxy) esters, 7, which were then oxidized with eerie ammonium nitrate and hydrolyzed under controlled acid conditions. https://www.lookchem.com/CASDataBase_10326-41-7.htm

2-Methyl-3-amino-5-phenyl-7-N, N-dimethylamino phenazinium chloride salts were synthesized in better yields via the cyclization of 4-amino-N,N-dimethylaniline with toluidine derivatives and aminobenzene under the oxidation of sodium bicarbonate. https://www.lookchem.com/CASDataBase_100-23-2.htm

Several unnatural N-acyl neuraminic acids (N-propionyl, N-hexanoyl, N-benzoyl, N-trifluoroacetyl, N-chloroacetyl, N-difluoroacetyl) were prepared enzymatically using immobilised sialic acid aldolase. N-Trifluoroacetyl-, N-chloroacetyl- and N-difluoroacetyl neuraminic acids were shown to enhance up to 10-fold the rate of association of influenza virus A to a sialoglycolipid neomembrane by surface plasmon resonance, and were found to act as weak inhibitors (K iapp 0.45-2.0 mM) of influenza virus neuraminidase. The N-propionyl, N-chloroacetyl- and N-difluoroacetyl neuraminic acids were found to be substrates for recombinant Escherichia coli CMP sialate synthase, to give the corresponding CMP-N-acyl-neuraminic acids. CMP-N-propionyl neuraminic acid was found not to be a substrate for CMP-N-acetyl neuraminic acid hydroxylase from pig submandibular gland. Copyright https://www.lookchem.com/CASDataBase_10036-64-3.htm

Poly-methyldopa (PMDP)-coated Fe 3 O 4 nanoparticles (Fe 3 O 4 @PMDP) have been synthesized through a simple and green procedure. In the present study, for the first time, Pd nanoparticles were successfully deposited using Fe 3 O 4 @PMDP as a core-shell magnetic coordinator and stabilizer agent. In this protocol, Pd ions were adsorbed on surfaces of Fe 3 O 4 @PMDP through immersion of the PMDP-coated Fe 3 O 4 nanoparticles into a palladium plating bath. Next, they were reduced in situ to palladium nanoparticles using PMDP's N-containing groups and reducing ability. The structure, morphology and physicochemical properties of the synthesized nanoparticles were characterized by different analytical techniques such as energy-dispersive X-ray spectroscopy (EDS), field emission scanning electron microscope (FESEM), Fourier-transform infrared spectroscopy (FT-IR) spectroscopy, high resolution transmission electron microscopy (HR-TEM), inductively coupled plasma (ICP), thermo gravimetric

The condensation of boron stabilised carbanions, MeS 2 BCHLiR 1 , (R 1 ≠H) with aliphatic aldehydes, R 2 CHO, followed by treatment with trifluoroacetic anhydride (TFAA) or N-chlorosuccinimide (NCS) is an unique, broadly applicable redox process that yields ketones, R 1 CH 2 COR 2 , directly and in high yields. The anion MeS 2 BCH 2 Li (MeS 2 BCHLiR 1 , R 1 =H) gives high yields of alkenes, R 2 CH=CH 2 in the same conditions. https://www.lookchem.com/CASDataBase_1007-32-5.htm In this study, vanadium-magnesium oxide (VMgO) catalysts with different vanadium loadings were synthesized by the impregnation method and characterized by BET, ICP-OES, IR, powder XRD, TEM, SEM, TPR-H 2 , and TPD of ammonia. The catalysts were te https://www.lookchem.com/CASDataBase_7642-04-8.htm 2-Methyl-3-amino-5-phenyl-7-N, N-dimethylamino phenazinium chloride salts were synthesized in better yields via the cyclization of 4-amino-N,N-dimethylaniline with toluidine derivatives and aminobenzene under the oxida

The use of highly active zinc, prepared by the Rieke method, for the direct preparation of benzylic zinc mesylate was investigated. The oxidative addition of highly active zinc to benzyl mesylate was easily completed under mild conditions. The resulting benzylic zinc mesylates were employed in subsequent cross-coupling reactions with a broad range of electrophiles, and the formation of the corresponding products was successful. https://www.lookchem.com/CASDataBase_101-82-6.htm

The reactions of various substrates including aliphatic hydrocarbons, aromatic compounds, and olefins were investigated in subcritical carbon tetrachloride. Ketones and sulfones were stable under the employed conditions. The coupling adducts between olefins and carbon tetrachloride were obtained from the reactions of olefins. https://www.lookchem.com/CASDataBase_76-83-5.htm

A new series of transition-metal-?-arene complexes has been prepared by a metal atom synthetic method.The deposition of Ni vapor, C6F5Br, and arenes has prodused high yields of (C6F5)2Ni-?-arene complexes.A variety of ?-arene ligands are η 6 bound by the (C6F5)2Ni moiety, resulting in soluble highly labile materials, where the ?-arene ligand is exchangeble at room temperature.These complexes have not been isolable when ?-bonding ligands other then C6F5 have been employed.The formation of the ?-toluene complex proceeds through a pseudostable C6F5NiBr species that can be trapped at -80 deg C with R3P but decomposes by reductive elimination of CF5-CF5 in the absence of R3P or electron-rich arenes.It is likely that C6F5NiBr-?-arene is formed initially, which then disproportionates to (C6F5)2Ni-?-arene and NiBr2.Due to the high lability of the ?-arene ligand, these complexes possess a rich chemistry.Displacement of the ?-arene ligand can bee carried out cleanly and in high yield by P(Et)3,

The adsorption of HCN and the reaction of HCN with NO 2 over Na-, and Ba-Y,FAU zeolite catalysts were investigated using in situ FTIR and TPD/ TPR spectroscopies. Both catalysts adsorb HCN molecularly at room temperature, and the strength of ads https://www.lookchem.com/CASDataBase_75-13-8.htm

Isomeric cage-like tetracopper(II) silsesquioxane complexes [(PhSiO 1.5 ) 12 (CuO) 4 (NaO 0.5 ) 4 ] (1a), [(PhSiO 1.5 ) 6 (CuO) 4 (NaO 0.5 ) 4 (PhSiO 1.5 ) 6 ] (1b) and binuclear complex [(PhSiO 1.5 ) 10 (CuO) 2 (NaO 0.5 ) 2 ] (2) have been studied by various methods. These compounds can be considered as models of some multinuclear copper-containing enzymes. Compounds 1a and 2 are good pre-catalysts for the alkane oxygenation with hydrogen peroxide in air in an acetonitrile solution. Thus, the 1a-catalyzed reaction with cyclohexane at 60°C gave mainly cyclohexyl hydroperoxide in 17% yield (turnover number, TON, was 190 after 230 min and initial turnover frequency, TOF, was 100 h -1 ). The alkyl hydroperoxide partly decomposes in the course of the reaction to afford the corresponding ketone and alcohol. The effective activation energy for the cyclohexane oxygenation catalyzed by compounds 1a and 2 is 16 ± 2 and 17 ± 2 kcal mol -1 , respectively. Selectivity parameters measured in the ox

Alkyl iodides and α-amino aldehydes can be homologated to the corresponding methyl esters and β-amino methyl esters, including β-amino-α-hydroxy methyl esters, using lithiated (dimethoxymethyl) diphenylphosphane oxide. The primary α,α-(dimethoxy) diphenylphosphane oxides obtained by this Horner-Wittig type process collapse to give the target esters under proton-catalyzed conditions in the presence of water. Detailed and carefully conducted mechanistic studies revealed that the diphenylphosphane oxide group is activated by protonation, and acts as the initial leaving group in this process. In the cases of adducts derived from the reaction of the phosphane oxide-stabilized anion with α-amino aldehydes, homologation to the β-amino- and β-amino-α-hydroxy methyl esters can be achieved by KOtBu-mediated elimination to the intermediate O,O-ketene acetals. These may either be allowed to react with water under acidic conditions to yield the β-amino methyl esters, or may be treated under the Sha

The synthesis and catalytic activity of a new class of 1,2,3-triazolyl N-heterocyclic carbene organocatalysts is described. These new catalysts chemoselectively facilitate the oxidative esterification of aldehydes. NMR acidity studies show an inverse correlation between triazolium acidity and reactivity. Kinetic studies show that the resting state of the catalyst involves a NHC-aldehyde adduct. A catalytically active intermediate was synthesized and characterized by X-ray diffraction as the initial carbene-aldehyde adduct. https://www.lookchem.com/CASDataBase_103-41-3.htm

Abstract: A series of silica-supported functionalized ionic liquids catalysts have been prepared and tested in the oxidative conversion of alcohols to nitriles with H 2 O 2 as the oxidant. The features of this heterogeneous reaction system were studied by tuning various reaction parameters including catalyst selection, amount of the catalyst, and effect of solvents. Among the catalysts, FeCl 4 –IL–SiO 2 exhibited the highest efficiency in direct oxidation of alcohols to nitriles under the optimized condition along with good recycle performance. Also, a possible catalytic mechanism is provided. Graphical abstract: [Figure not available: see fulltext.] https://www.lookchem.com/CASDataBase_100-70-9.htm

Pyrolysis of 2-phenylimino-3-arylamino-4-thiazolidinone I, II (Ar = Ph, p-tolyl) by heating at ca. 250°C in a sealed tube gives rise to H 2 S, benzonitrile, acetophenone, arylamines, phenyl isothiocynate, thioglycolic acid, arylhydrazines, N-phenyl-N'-aryl thiourea, benzimidazole, and 3-phenyl-1,2,4-benzotriazines. Analogous results in addition to toluene, bibenzyl, stilbene, bibenzylamine and acetamide were also obtained on pyrolysis of 2-phenylimino-3-benzylamino-4-thiazolidinone (III). In the presence of isoquinoline as a radical trap, (III) gave 1-benzylisoquinoline beside the previous products. A free radical mechanism has been postulated to take place through the homolysis of the N-N and C-S bonds to account for the identified products. https://www.lookchem.com/CASDataBase_102-08-9.htm

One-electron redox potentials of some purine and pyrimidine derivatives were determined by pulse radiolysis from electron transfer equilibria involving their and other free radicals.The redox potentials were determined at pH 13 by using p-methoxyphenol (E=0.4 V), Trolox C (E=0.19 V), and tryptophan (E=0.56 V) as references.The lowest oxidation potential measured for DNA bases was guanosine (E=0.72 V vs.NHE), and the highest was for 1-methylpyrimidines (E ca. 1.6 V) Uric acid (E=0.26 V) and isobarbituric acid (E=0.13 V) were found to have the lowest potentials. https://www.lookchem.com/CASDataBase_73-40-5.htm

The [1,3]-alkoxy rearrangement reactions of N-alkoxyanilines were efficiently catalyzed by cationic N-heterocyclic carbene (NHC)-Cu catalysts in affording 2-alkoxyaniline derivatives in good to excellent yields with high functional group compatibility. For N-alkoxyanilines having an electron-withdrawing substituent at the meta-position, the alkoxy group selectively migrated to the more hindered ortho-position. In contrast, the alkoxy group migrated to the less hindered ortho-position for N-alkoxyanilines having an electron-donating substituent. Mechanistic studies suggest that the rearrangement reactions proceed via an intramolecular route. https://www.lookchem.com/CASDataBase_100-65-2.htm

Chemoselective deprotection of methyl esters can be achieved under non- hydrolytic and virtually neutral conditions by treatment with thiophenol in N-methyl-2-pyrrolidone (NMP) in the presence of a catalytic amount of K 2 CO 3 . https://www.lookchem.com/CASDataBase_104-01-8.htm

Methyl and benzyl ethers have been cleaved with a combination of reagents consisting of chlorotrimethylsilane and acetic anhydride containing a catalytic amount of concentrated sulfuric acid.Methylthiomethyl ethers yield the correponding acetoxymethyl ethers with chlorotrimethylsilane and acetic anhydride.Comparative study with the borontrifluoride etherate and acetic anhydride method of ether cleavage suggests that chlorotrimethylsilane and acetic anhydride (conc.H2SO4 catalysis) could be a useful alternative to it. https://www.lookchem.com/CASDataBase_747-90-0.htm

We report a low-cost and efficient catalytic system, involving in situ generated ligand-free Ni NPs, methanol and sodium borohydride, for the semihydrogenation of alkynes under ambient conditions. This catalytic system exhibits remarkably high activity, satisfactory cis-selectivity for internal alkynes, good stability and general applicability. https://www.lookchem.com/CASDataBase_7642-15-1.htm

A new ruthenium catalytic system for the syntheses of secondary and tertiary amines via reductive N-alkylation of nitriles and N-alkylation of primary amines is proposed. Isomeric complexes 8 catalyze transfer hydrogenation and N-alkylation of nitriles in ethanol to give secondary amines. Unsymmetrical secondary amines can be produced by N-alkylation of primary amines with alcohols via the borrowing hydrogen methodology. Aliphatic amines were obtained with excellent yields, while only moderate conversions were observed for anilines. Based on kinetic and mechanistic studies, it is suggested that the rate determining step is the hydrogenation of intermediate imine to amine. Finally, ammonium formate was applied as the amination reagent for alcohols in the presence of ruthenium catalyst 8. Secondary amines were obtained from primary alcohols within 24 hours at 100 °C, and tertiary amines can be produced after prolonged heating. Secondary alcohols can only be converted to secondary amines

A procedure for the synthesis of alkyl formates, 1,ω-alkanediyl diformates, and unsaturated analogs from alkyl (or 2-alkenyl) halides and sodium formate under solid/liquid phase-transfer conditions is reported.For conversion into alcohols or diols, respectively, the formic esters can be directly hydrolyzed in the reaction mixture of their preparation.Using a related procedure, cyclic ethers are prepared from 1,ω-dichloroalkanes, sodium formate, and potassium hydroxide under solid/liquid phase-transfer conditions. https://www.lookchem.com/CASDataBase_75-21-8.htm

Highly fluorinated tetraphenyl borate anions are of importance as weakly coordinating anions in metalorganic reactions. However, at high positive potentials their electrochemical stability in organic solvents is not sufficient. This was investigated by a comprehensive cyclic voltammetry study and can be used synthetically to generate highly fluorinated biphenyls. https://www.lookchem.com/CASDataBase_434-90-2.htm

Immobilization of rhodium (palladium)-copper-chloride catalytic systems in ionic liquids as high-boiling-point solvents affects the distribution of propane oxidation products: the acetone yield increases and the yield of alcohols decreases. Propane is oxidized to acetone, bypassing the isopropanol formation step. Methane is oxidized under more severe conditions than propane, giving methyl trifluoroacetate as the main product. Mechanisms of action of the catalytic systems based on rhodium and palladium are close to each other and likely include oxo or peroxo complexes as intermediates. https://www.lookchem.com/CASDataBase_431-47-0.htm

Several polychloro(trifluoromethyl)benzenes have been prepared by treatment of the corresponding polychlorobenzenes with CCl3F and AlCl3.The resulting trifluoromethyl derivatives, by reaction with the same inorganic halide in CS2, give their trichloromethyl analogues. https://www.lookchem.com/CASDataBase_75-71-8.htm

The interaction of a range of organic halides with (Cl3Si)2 or (Me3Si)2 in the presence of a variety of transition metal catalysts (very predominantly Pd 0 or Pd II complexes) have been examined.PhSiMe3 was formed from PhCl (m.y. = maximum yield), PhBr (m.y., 92percent, with as catalyst (L=PPh3)), and (contrary to earlier reports) PhI (m.y. 51percent, with ).MeSiCl3 was formed from MeBr (m.y., 78percent with ) and MeI (m.y., 91percent with ), and EtSiCl3 from EtBr (m.y., 49percent, with ; L''=P(C6H4OMe-p)3) and EtI (m.y. 45percent, with ).Me4Si was satisfactorily formed from MeBr (m.y. 42percent, with ).Evidence was obtained for the formation of Me3SiCF3 from CF3I.Very poor yields of XC6H4CH2SiMe3 were obtained from XC6H4CH2Br (X=H or p-Me) (with X=H some PhSiMe3 was formed), but p-O2NC6H4CH2SiMe3 was formed in 48percent yield from p-O2NC6H4CH2Cl with as catalyst.PhCOSiMe3 was formed from PhCOCl (m.y. 52percent with ).The nickel complex was moderately effective as a catal

The complex [Pd(2-Phpy)(μ-Cl)] 2 reacts with pyridines (L=pyridine, α-picoline and γ-picoline), amines (L=isopropylamine, tert-butylamine) and ammonia to form the corresponding ortho-palladated derivatives [Pd(2-Phpy)CIL]. The compounds have been characterized by C, H and N analyses and spectroscopic methods (IR and 1 H and 13 C NMR). TG, DTG and DSC studies of the complexes were carried out in dynamic nitrogen atmosphere. From DSC analyses the heats of decomposition were calculated. The kinetics of the first step of thermal decomposition were evaluated from TG data by isothermal methods for L=pyridine and isopropylamine. The activation energies obtained are in the range 90-100 kJ mol -1 . The best fitting for data was observed for R2 and A1.5 kinetic models. https://www.lookchem.com/CASDataBase_75-31-0.htm

Enzyme-catalyzed asymmetric dihydroxylation is a powerful tool for the selective oxyfunctionalization of various organic compounds. By applying Rieske non-heme dioxygenases (ROs), molecular oxygen and a reduction equivalent are needed for the generation of vicinal cis-diols. We report a comprehensive mutagenesis study of the active site of the naphthalene dioxygenase from Pseudomonas sp. NCIB 9816-4 comprising 62 variants. We aimed to understand the important structure–function relationships by investigating different substituted arene substrates and the geometry of the active site. Introducing single-point mutations at positions F202, A206, V260, H295, F352, and L307 resulted in drastic shifts in the reaction specificity, regioselectivity, and stereoselectivity (≥90 %) while maintaining the residual activity towards the natural substrate naphthalene. https://www.lookchem.com/CASDataBase_4217-66-7.htm

Isotopologs are powerful tools for investigating biological systems. We report a biosynthetic-cascade synthesis of Trp isotopologs starting from indole, glycine, and formaldehyde using the enzymesl-threonine aldolase and an engineered β-subunit of tryptophan synthase. This modular route to Trp isotopologs is simple and inexpensive, enabling facile access to these compounds. https://www.lookchem.com/CASDataBase_73-22-3.htm

Based on the supramolecular interaction between vancomycin (Van), an antibiotic glycopeptide, and D-Ala-D-Ala (DADA) dipeptides, a novel class of artificial metalloenzymes was synthesized and characterized. The presence of an iridium(III) ligand at the N-terminus of DADA allowed the use of the metalloenzyme as a catalyst in the asymmetric transfer hydrogenation of cyclic imines. In particular, the type of link between DADA and the metal-chelating moiety was found to be fundamental for inducing asymmetry in the reaction outcome, as highlighted by both computational studies and catalytic results. Using the [IrCp*(m-I)Cl]Cl Van complex in 0.1 M CH3COONa buffer at pH 5, a significant 70% (S) e.e. was obtained in the reduction of quinaldine B. https://www.lookchem.com/CASDataBase_1780-19-4.htm

Reactions of the substituted tetramethylcyclopentadienes [C 5 HMe 4 R] [R?=? t Bu, Ph, CH 2 CH 2 C(CH 3 ) 3 ] with Mo(CO) 3 (CH 3 CN) 3 in refluxing xylene gave a series of dinuclear molybdenum carbonyl complexes [(η 5 -C 5 Me 4 R)Mo(CO) 3 ] 2 [R?=? t Bu (1), Ph (2), CH 2 CH 2 C(CH 3 ) 3 (3)], [(η 5 -C 5 Me t Bu)Mo(μ-CO) 2 ] 2 (4)], and [(η 5 -C 5 Me 4 ) t Bu] 2 Mo 2 O 4 (μ-O) (5)], respectively. Complexes 1–5 were characterized by elemental analysis, IR, 1 H NMR, and 13 C NMR spectroscopy. In addition, their crystal structures were determined by X-ray crystal diffraction analysis. The catalytic activities of complexes 1–3 in Friedel–Crafts acylation in the presence of o-chloranil has also been investigated; the reactions were achieved under mild conditions to give the corresponding products in moderate yields. https://www.lookchem.com/CASDataBase_1023-17-2.htm

A fine-grained AZ91 alloy was prepared by equal channel angular pressing (ECAP). The evolution of the microstructure and the deformation behavior were investigated as a function of the number of ECAP passes. At room temperature the tensile strength of the ECA pressed specimens is higher than that of the initial state due to the grain refinement and the increase of the dislocation density during ECAP. Above 200 °C the ductility increases due to the increase of the relative fraction of c + a dislocations and also owing to the breakage of the rod-like Al 12 Mg 17 precipitates during ECAP processing. https://www.lookchem.com/CASDataBase_7439-95-4.htm

In the ferrous ion induced decomposition of alkyl hydroperoxides in the presence of cupric halides or pseudohalides, intramolecular functionalization with ligand transfer from cupric salts to δ-carbon atom, is achieved. https://www.lookchem.com/CASDataBase_1003-38-9.htm

The epitaxial lift-off process allows the separation of a thin layer of III/V material from the substrate by selective etching of an intermediate AlAs layer with HF In a theory proposed for this process, it was assumed that for every mole of AIAs dissolved three moles of H 2 gas are formed. In order to verify this assumption the reaction mechanism and stoichiometry were investigated in the present work. The solid, solution and gaseous reaction products of the etch process have been examined by a number of techniques, It was found that aluminum fluoride is formed, both in the solid form as well as in solution. Furthermore, instead of H 2 arsine (AsH 3 ) is formed in the etch process. Some oxygen-related arsenic compounds like AsO, AsOH, and AsO 2 have also been detected with gas chromatography/mass spectroscopy. The presence of oxygen in the etching environment accelerates the etching process, while a total absence of oxygen resulted in the process coming to a premature halt. It is a

The coordination adducts of MnCl 2 , FeCl 3 , CoCl 2 , NiCl 2 and CuCl 2 with DMF were isolated and characterized by elemental analysis, magnetic moments, UV-VIS spectroscopy, IR spectroscopy and thermal analysis techniques. The shift of the CO stretching vibration to low frequency indicated that DMF is bonded through oxygen to the metals. On the basis of spectral and elemental analysis data, the complexes have dimeric and trimeric structures achieved by the chlorine bridges. The complexes do not have melting points and undergo decomposition after dehydration. The decomposition of DMF in the complexes occurs in several stages and the last stages of decomposition always corresponds to decomposition or sublimation of the respective metal chlorides to produce the respective metal. https://www.lookchem.com/CASDataBase_7439-96-5.htm

o -Iodoxybenzoic acid (IBX) is confirmed as a powerful tool for the oxidation of hydroxylamines. The synthetic route is demonstrated as efficient and user friendly, and is exploited on various carbohydrate-derived N,N-disubstituted hydroxylamines (cyclic, acyclic, and functionalized ones), affording the corresponding nitrones in good yields and regioselectivity. N-Monosubstituted hydroxylamines revealed an interesting divergent behavior depending on the reaction conditions. While IBX oxidation in dimethyl sulfoxide at 45 °C furnished oximes as reported, the oxidation in dichloromethane at room temperature afforded efficiently the unusual corresponding nitroso dimers. https://www.lookchem.com/CASDataBase_100-64-1.htm

We report a "macrocycle route" toward aliskiren, a drug presently marketed for the treatment of hypertension, using a highly stereocontrolled approach starting from a common "isopropyl chiron". Highlights of the synthesis include a challenging RCM reaction to produce a nine-membered unsaturated lactone, a highly stereoselective catalytic Du Bois aziridination, and a regio- and diastereoselective aziridine ring-opening to a vicinal amino alcohol. https://www.lookchem.com/CASDataBase_173334-57-1.htm

The 147-nm photolyses of 2,2-dimethylbutane, 2,2,3-trimethylbutane, 2,2,3-trimethyl-2-silabutane (isopropyltrimethylsilane), and 2,2,3,3-tetramethyl-2-silabutane (tert-butyltrimethylsilane) are reported.In addition, the mercury-sensitized photolyses of i-C4H10, trimethylsilane, and mixtures of i-C4H10 and trimethylsilane are reported which give disproportionation to combination (D/C) ratios of 2.1+- 0.2 and 0.28+-0.05 for (CH3)3C + (CH3)3C and (CH3)3Si + (CH3)3Si, respectively, and D/C ratios of 1.86+- 0.15and 0.55+- 0.08 for (CH3)C + (CH3)3Si to form 2-methyl-2-silapropene and i-C4H8, respectively.With the completion of this work, several trends and generalizations can be drawn concerning the importance of various processes in linear vs. branched alkanes and alkylsilanes.These conclusions are summarized in this report. https://www.lookchem.com/CASDataBase_75-76-3.htm

We have developed a new method to synthesize magnetically separable Fe 3 O 4 @AHBA@Pd(0) (AHBA = 3-amino-4-hydroxybenzoic acid) heterogeneous nanocatalyst via anchoring of palladium(0) on the surface of AHBA-coated Fe 3 O 4 nanoparticles. The synthesized nanocatalyst was characterized by FT-IR, PXRD, ICP, XPS, FESEM, EDX, TEM, TGA, BET, and FT-RAMAN analysis. X-ray photoelectron spectroscopy (XPS) indicated the presence of Pd(0) on the surface of Fe 3 O 4 @AHBA. BET analysis exhibits high surface area of the prepared nanocatalyst with catalytic activity toward Heck coupling reactions with high turnover frequency (TOF) at 60 °C in water–acetonitrile within 2 h. The nanocatalyst can be easily recovered from the reaction mixture by using an external magnet and recycled six times without significant decrease in its catalytic activity. All the isolated products are obtained as solids or oils, fully characterized by 1 H-NMR spectroscopy. https://www.lookchem.com/CASDataBase_4360-47-8.htm

– Antimony trichloride (SbCl3) was found to be an effective catalyst (1 mol%) for one-pot synthesis of quinazolin-4(3H)-ones in good to excellent yields using anthranilamide and acyl chlorides under microwave irradiation. This method has the advantages of simplicity, mild reaction conditions, highly tolerant to several functional groups, as well as the avoidance of hazardous solvents. https://www.lookchem.com/CASDataBase_1769-24-0.htm

Solvolitic rate constants for secondary mesylates and tosylates in aqueous ethanol and in aqueous acetone are correlated with Winstein-Grunwald Y values.Curvature of these plots is greatest for tosylates in aqueous ethanol, especially for 2-adamantyl.Because mesylates show little or no curvature, it is argued that the results cannot be explained by mechanistic changes but by solvation effects of the leaving group in the mixed solvents.The parameter, m, measuring response to solvent ionizing power varies from 0.68 for isopropyl to 1.21 for 2-adamantyl mesylate in aqueosus acetone at 25 deg C.An alternative solvent ionizing power parameter for tosylates, Y OTs , and the solvent nucleohpilicity parameter, N OTs , are evaluated for 20percent ethanol/water, 20percent acetone/water, and 40percent acetone/water.It is proposed that solvolyses of substrates having the same (or very similar) leaving group should be compared if reliable mechanistic information (e.g., nucleophilic solvation effec

The hexagonal-layered Ti 2 InC compound is a member of the large family of lamellar materials that crystallize in the hexagonal structure with space group P 6 3 / mmc, which are isomorphs with the Cr 2 AlC compound, and known as H-phase. In this work the Ti 2 InC phase is investigated by X-ray diffraction, magnetization and resistivity measurements. Susceptibility and resistivity measurements display superconducting critical temperature close to 3.1 K. In spite of the great number of compounds which belong to this family, superconductivity has been reported only for four cases: Mo 2 GaC, Nb 2 SC, Nb 2 AsC and Nb 2 SnC. This work supports the existence of a new class of superconducting materials that crystallize in an H-phase. https://www.lookchem.com/CASDataBase_7440-74-6.htm

An efficient and versatile synthetic method has been developed and utilized for the stereoselective synthesis of (R)-(+)-goniothalamin 1, (R)-(+)-kavain 2 and (S)-(+)-7,8-dihydrokavain 3. Application of the Cosford protocol and direct conversion of aldehydes to β-keto-esters are the key steps in our approach. https://www.lookchem.com/CASDataBase_17303-67-2.htm

The preparation of a novel polystyrene-supported dehydrating agent and its application to the synthesis of 1,3,4-oxadiazoles under thermal and microwave conditions is described. An alternative procedure using tosyl chloride and P-BEMP is also presented. https://www.lookchem.com/CASDataBase_725-12-2.htm

The metallic Cu flakes prepared by milling metallic Cu powder were controllably oxidized in air at different temperatures to obtain the Cu-based catalysts containing multicomponents of Cu, Cu 2 O, and CuO. These catalysts are explored in the Rochow reaction using silicon powder and methyl chloride (MeCl) as reactants to produce dimethyldichlorosilane (M2), which is the most important organosilane monomer in the industry. The samples were characterized by X-ray diffraction, temperature-programmed reduction, thermogravimetric analysis, oxidimetry analysis, particle size analysis, transmission electron microscopy, and scanning electron microscopy. Compared to the metallic Cu powder and Cu flakes, the controllably oxidized Cu flakes containing Cu, Cu 2 O, and CuO species show much higher M2 selectivity and silicon conversion in the Rochow reaction. The enhanced catalytic performance may stem from the larger interfacial contact among the gas MeCl, solid Si particles, and solid Cu-based cata

An easily prepared masked N-heterocyclic carbene, 1,3-dimethylimidazolium-2-carboxylate (DMI-CO 2 ), was investigated as a “green” and inexpensive organocatalyst for the alkylation of phenols. The process made use of various low-toxicity and renewable alkylating agents, such as dimethyl- and diethyl carbonate, in a focused microwave reactor. DMI-CO 2 was found to be a very active catalyst and excellent yields of a range of aryl alkyl ethers were obtained under relatively benign conditions. The observed difference in the conversion behavior of phenol methylation, in the presence of either the carbene or 1,8-diazabicycloundec-7-ene (DBU) catalyst, was rationalized on the basis of mechanistic investigations. The primary mode of action for the N-heterocyclic carbene is nucleophilic catalysis. Activation of the dialkyl carbonate electrophile results in concomitant evolution of an organo-soluble alkoxide, which deprotonates the phenolic starting material. In contrast, DBU is initially proto

The construction of carboxylic acid compounds in a selective fashion from low value materials such as alkenes remains a long-standing challenge to synthetic chemists. In particular, β-addition to styrenes is underdeveloped. Herein we report a new electrosynthetic approach to the selective hydrocarboxylation of alkenes that overcomes the limitations of current transition metal and photochemical approaches. The reported method allows unprecedented direct access to carboxylic acids derived from β,β-trisubstituted alkenes, in a highly regioselective manner. https://www.lookchem.com/CASDataBase_1009-67-2.htm

Photoactive two-dimensional covalent organic frameworks (2D-COFs) have become promising heterogenous photocatalysts in visible-light-driven organic transformations. Herein, a visible-light-driven selective aerobic oxidation of various small organic molecules by using 2D-COFs as the photocatalyst was developed. In this protocol, due to the remarkable photocatalytic capability of hydrazone-based 2D-COF-1 on molecular oxygen activation, a wide range of amides, quinolones, heterocyclic compounds, and sulfoxides were obtained with high efficiency and excellent functional group tolerance under very mild reaction conditions. Furthermore, benefiting from the inherent advantage of heterogenous photocatalysis, prominent sustainability and easy photocatalyst recyclability, a drug molecule (modafinil) and an oxidized mustard gas simulant (2-chloroethyl ethyl sulfoxide) were selectively and easily obtained in scale-up reactions. Mechanistic investigations were conducted using radical quenching expe

The kinetics of the thermal intramolecular redox reaction between NO - and Co(III) in Cl2 has been studied by means of thermogravimetric and thermomagnetic analyses.The reaction is found to follow the first-order equation, with ΔH(excit.) = 129 +/- 6 kJ mol -1 and ΔS(excit.) = 14 +/- 16 J mol -1 K -1 .These results are compared with the kinetics of other nitrosylcobalt(III) and hexaamminecobalt(III) complexes. https://www.lookchem.com/CASDataBase_7646-79-9.htm

A highly selective self-condensation of glycolaldehyde to different C 4 molecules has been achieved using Lewis acidic stannosilicate catalysts in water at moderate temperatures (40–100 °C). The medium-sized zeolite pores (10-membered ring framework) in Sn-MFI facilitate the formation of tetrose sugars while hindering consecutive aldol reactions leading to hexose sugars. High yields of tetrose sugars (74 %) with minor amounts of vinyl glycolic acid (VGA), an α-hydroxyacid, are obtained using Sn-MFI with selectivities towards C 4 products reaching 97 %. Tin catalysts having large pores or no pore structure (Sn-Beta, Sn-MCM-41, Sn-SBA-15, tin chloride) led to lower selectivities for C 4 sugars due to formation of hexose sugars. In the case of Sn-Beta, VGA is the main product (30 %), illustrating differences in selectivity of the Sn sites in the different frameworks. Under optimized conditions, GA can undergo further conversion, leading to yields of up to 44 % of VGA using Sn-MFI in wa

2-Halogenoalkoxytributyltin compounds have been prepared from tributylethoxytin and 1,2-halohydrins. The thermal degradation and its mechanism are investigated. These reactions offer a convenient way to prepare epoxides. https://www.lookchem.com/CASDataBase_75-56-9.htm

We have identified a novel one-pot method for the synthesis of β-amino alcohols, which is based on C-H bond hydroxylation at the benzylic α-carbon atom with a subsequent nitrile or amide functional group reduction. This cascade process uses molecular oxygen as an oxidant and sodium bis(2-methoxyethoxy)aluminum hydride as a reductant. The substrate scope was examined on 30 entries and, although the respective products were provided in moderate yields only, the above simple protocol may serve as a direct and powerful entry to the sterically congested 1,2-amino alcohols that are difficult to prepare by other routes. The plausible mechanistic rationale for the observed results is given and the reaction was applied to a synthesis of a potentially bioactive target. This journal is https://www.lookchem.com/CASDataBase_103-81-1.htm

The stoichiometries of the reaction between alkali metal radical anions of biphenyl, naphthalene, phenanthrene and anthracene, and methanol and/or other proton donors have been determined by the magnetic titration technique. In the case of naphthalene radical anion and, for example, methanol as the proton source, the stoichiometry was found to be cation-dependent: Li, 2: 1; Na, 1.75: 1; K, 1.33: 1. The reaction products using the experimentally determined stoichiometric conditions were ca. 95% naphthalene and 5% dihydronaphthalene(s). Thus, a marked discrepancy is observed between the protons used and those incorporated into the naphthalene molecule. Radical anions, at concentrations comparable with those of preparative reactions, react with carbon acids or amines according to the first-order kinetic law, although the initial concentrations of the two reactants were of the same order of magnitude or even equal. Lithium anthacene radical anion reacts with phenylacetylene and diethylamin

Carboxyl groups protected as the amides derived from 5,6-dihydrophenanthridine are stable under a wide range of conditions and can be selectively deprotected by oxidation on treatment with cerium(IV) https://www.lookchem.com/CASDataBase_434-13-9.htm

Nickel(I)octaethylisobacteriochlorin anion (Ni(I)OEiBC - ) reacts extremely rapidly with aliphatic halides and methyl tosylate in homogeneous DMF solution.The reactivity sequence, CH3 > primary > secondary <*> tertiary, and the rate law accord with an S N 2-like process for the carbon-halogen bond scission.However, the main products of the reactions derive from free radicals.The rate for methyl chloride is 2000 times faster than the corresponding reaction with the super nucleophile Co(I)B12 s -1 and the rate constant for isopropyl bromide is 350 times greater than that observed with CpFe(CO)2 - .The results indicate NiOEiBC - is the fastest nucleophile on record.Studies of the influence of solvent and reactant deuteration and the influence of anion and radical scavengers upon the product distribution suggest the intermediacy of at least one and possibly two nickel alkyls of fleeting lifetime.A novel explanation for the unusual speed of these reactions is put forward.It en

The global energy demand requires high energy conversion and storage devices. In order to enhance the utility of these devices, highly efficient, stable and cost effective catalyst and electrode materials are required. In the present study, the nano-size single phase molybdenum disulphide (MoS 2 ) has been synthesized at 700 °C via reduction-sulphurization method in a specially designed autoclave. The UV–Visible and photoluminescence results are in accordance with the Raman spectroscopy studies, confirming few layers (5–6 layers) of synthesized MoS 2 exhibiting a band gap of 2.29 eV. Based on structural and morphological results, the formation mechanism from MoO 3 to MoS 2 is proposed. The as-synthesized samples are expected to be promising stable catalyst for hydrogen evolution reaction (HER) through water splitting in both acidic and basic medium. The cyclic voltammetry (CV) test for 1000 cycles in basic medium shows enhanced stability of pure phase MoS 2 . The electrochemical dou

An immobilized iridium complex photocatalyst Ir(ppy) 2 (PDVB-py) was synthesized by immobilization of the iridium complex onto the nanoporous vinylpyridine-divinylbenzene copolymer (PDVB-py). Its application for the synthesis of amides, nitriles, and anhydrides was reported via reactions under the action of the visible-light-driven in situ generated Vilsmeier-Haack reagent from CBr 4 in DMF. The results showed that this heterogeneous photocatalyst has extremely high activity and excellent stability to be recycled five times. https://www.lookchem.com/CASDataBase_7472-54-0.htm

Development of heterogeneous catalysts for alcohol transformation into nitriles under oxidant-free conditions is a challenge. Considering the C-H activation on α-carbon of primary alcohols is the rate-determining step, decreasing the activation energy of C-H activation is critical in order to enhance the catalytic activity. Several NiM/Al 2 O 3 bimetallic catalysts were synthesized and scrutinized in catalytic transformation of 1-butanol to butyronitrile. Ni-Cu was identified as a suitable combination with the optimized Ni 0.5 Cu 0.5 /Al 2 O 3 catalyst exhibiting 10 times higher turnover frequency than Ni/Al 2 O 3 catalyst. X-ray absorption spectroscopy (XAS) and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) revealed that the NiCu particles in the catalyst exist in the form of homogeneous alloys with an average size of 8.3 nm, providing an experimental foundation to build up a catalyst model for further density functional theory (DFT) calculati

(Chemical Equation Presented) Room-temperature reduction of aromatic nitro groups to amines can be accomplished in high yield, with wide functional group tolerance and short reaction times (30 min) using a combination of palladium(II) acetate, aqueous potassium fluoride, and polymethylhydrosiloxane (PMHS). Replacing PMHS/KF with triethylsilane allows aliphatic nitro groups to be reduced to their hydroxylamines. https://www.lookchem.com/CASDataBase_103-90-2.htm

The preparation of all possible stereoisomers of a given chiral molecule bearing multiple stereocenters by a simple and unified method is a significant challenge in asymmetric catalysis. We report stereodivergent allylic substitutions with aryl acetic acid esters catalyzed synergistically by a metallacyclic iridium complex and benzotetramisole. Through permutations of the enantiomers of the two chiral catalysts, all four stereoisomers of the products bearing two adjacent stereocenters are accessible with high diastereoselectivity and enantioselectivity. The resulting chiral activated ester products can be converted readily to enantioenriched amides, unactivated esters, and carboxylic acids in a onepot manner. https://www.lookchem.com/CASDataBase_103-36-6.htm

A full account of concise, enantioselective syntheses of the anticancer agent (-)-salinosporamide A and derivatives, including (-)-homosalinosporamide, that was inspired by biosynthetic considerations is described. The brevity of the synthetic strategy stems from a key bis-cyclization of a β-keto tertiary amide, which retains optical purity enabled by A 1,3 -strain rendering slow epimerization relative to the rate of bis-cyclization. Optimization studies of the key bis-cyclization, enabled through byproduct isolation and characterization, are described that ultimately allowed for a gram scale synthesis of a versatile bicyclic core structure with a high degree of stereoretention. An optimized procedure for zincate generation by the method of Knochel, generally useful for the synthesis of salino A derivatives, led to dramatic improvements in side-chain attachment and a novel diastereomer of salino A. The versatility of the described strategy is demonstrated by the synthesis of designed d

A kinetic study on nucleophilic substitution reactions of phenyl Y-substituted-phenyl carbonates (5a-5j) with ethylamine in 80 mol % H2O/20 mol % DMSO at 25.0 ± 0.1 oC is reported. The plots of kobsd vs. [amine] are linear for the reactions of substrates possessing a strong electron-withdrawing group (EWG) but curve upward for those of substrates bearing a weak EWG, indicating that the electronic nature of the substituent Y in the leaving group governs the reaction mechanism. The reactions have been concluded to proceed through a stepwise mechanism with one or two intermediates (a zwitterionic tetrahedral intermediate T± and its deprotonated form T-) depending on the nature of the substituent Y. Analysis of Bronsted-type plots and dissection of kobsd into microscopic rate constants have revealed that the reactions of substrates possessing a strong EWG (e.g., 5a-5f) proceed through T± with its formation being the rate-determining step, while those of substrates bearing a weak EWG (e.g.,

This study identifies a series of Ir-bicyclic phosphoroamidite-oxazoline/thiazole catalytic systems that can hydrogenate a wide range of minimally functionalized olefins (including E- and Z-tri- and disubstituted substrates, vinylsilanes, enol phosphinates, tri- and disubstituted alkenylboronic esters, and ?±,?2-unsaturated enones) in high enantioselectivities (ee values up to 99%) and conversions. The design of the new phosphoroamidite-oxazoline/thiazole ligands derives from a previous successful generation of bicyclic N-phosphane-oxazoline/thiazole ligands, by replacing the N-phosphane group with a p-acceptor biaryl phosphoroamidite moiety. A small but structurally important family of Ir-phosphoroamidite-oxazoline/thiazole precatalysts has thus been synthesized by changing the nature of the Ndonor group (either oxazoline or thiazole) and the configuration at the biaryl phosphoroamidite moiety. The substitution of the N-phosphane by a phosphoroamidite group in the bicyclic N-phosphane

A successful application of the aminobarbituric acid-hydantoin rearrangement to produce a bicyclic carbamoylhydantoin from an intermediate spirobarbituric acid is reported. 7a-Phenylcarbamoyl-tetrahydro-1H-pyrrolo[1,2- c]imidazole-1,3(2H)-dione (8) was obtained in a one-pot multistep reaction of 1-acetyl-2,2-bis(ethoxycarbonyl)pyrrolidine (5) and phenylurea in the presence of sodium ethoxide. Under less severe conditions, 5 and phenylurea were reacted to afford 1-acetyl-7-phenyl-triaza[4,5]decane-6,8,10-trione (6). The structural elucidation of the bicyclic hydantoin 8 and the spirobarbituric acid 6 was based on relevant nmr signals in accordance with those of reference compounds, i.e. monocyclic hydantoins 4a,b and acetamidobarbituric acids 2a-c. The latter compounds were newly prepared from diethyl acetamidomalonates 1 and phenylurea. https://www.lookchem.com/CASDataBase_101-99-5.htm

This communication describes a ruthenium nanoparticle-catalyzed reduction of nitroarenes giving azoxyarenes, azoarenes, or anilines in good to excellent yields using ethanol as a hydrogen source. Copyright https://www.lookchem.com/CASDataBase_100-17-4.htm

This protocol describes the catalytic use of diacetoxyiodobenzene (DIB) for the efficient transamidation of carboxamides with amines under mild conditions. https://www.lookchem.com/CASDataBase_103-89-9.htm

Aromatic amines undergo substitution with copper(II)bromide that is in competition with substitutive deamination when these reactions are performed with tert-butyl nitrite.Except for the exceptionally reactive 4-substituted 1-aminonaphthalenes,which undergo selective bromine substitution at the 1- and 2-positions in relatively high isolated yields,rates for oxidative bromination and substitutive deamination are not sufficiently different that selective multiple bromination can be achieved.Oxidative bromination of N,N-dimethylaniline by copper(II)bromide occurs with partial dealkylation,and nitration products are observed from reactions performed with copper(II)bromide and tert-butyl nitrite.Implications of these results for the successful utilization of copper(II)bromide/tert-butyl nitrite combinations in substitutive deamination reactions of aromatic amines are discussed.Multiply brominated aromatic compounds are produced from aromatic amines in high yield through treatment of the aro

A new method based on the electrostatic interaction of a novel anionic water soluble polymer P1 with a positively charged polypeptide Arg 6 was developed for a continuous and real time turn on assay for the enzymatic activity of trypsin under alkaline conditions with a limit of detection of 0.17 nM. This method was also able to screen the inhibitors of trypsin. P1 fluorescence intensity was significantly decreased by the positively charged Arg 6 due to the electrostatic interaction, whereas the enzymatic action recovered P1 fluorescence due to the fragmentation of Arg 6 into small positively charged fragments and these were unable to quench the P1 fluorescence. Therefore, by triggering the fluorescence intensity change, it was possible to assay the enzymatic activity. Use of water soluble conjugated polymer P1 and no labeling on the substrate enhances the utility of this method significantly. The Royal Society of Chemistry. https://www.lookchem.com/CASDataBase_74-79-3.htm

Methods for the preparation of iron whiskers in chemical transport reactions of thermal dissociation of iron penta- and dodecacarbonyls and carbidocarbonyl clusters Fe 5 C(CO) 15 were described. The morphology, structure, and chemical composition of the whiskers were studied. The main factors determining the growth rate and mechanical properties of the whiskers were revealed. A model for the mechanism of thermal dissociation of iron carbonyls was proposed. This process was shown to be a chain radical ion reaction initiated via the scheme of activating complex formation. Analogies between the thermal dissociation of iron carbonyls in the adsorption layer and the known radical ion processes in the liquid and gas phases were found. https://www.lookchem.com/CASDataBase_17685-52-8.htm

Phenylphosphinic acid and dialkylsulfoxides are found to be alternative reagents for respectively the reducing reagent (formic acid) and the alkylating reagent (aldehyde) currently used for secondary amines N-alkylation. Primary amines do not react with this system, but phenylglycine is decarboxilated to benzylamine. https://www.lookchem.com/CASDataBase_103-83-3.htm

Catalytic hydrodechlorination of carbon tetrachloride (CCl 4 ) is an effective measure to remove CCl 4 due to its pollutant character. The dechlorination of CCl 4 to dichloromethane (CH 2 Cl 2 ) and chloroform (CHCl 3 ) with a molar ratio of 3:2 was catalyzed by carbon-supported silver (Ag/C) catalyst in methanol solution. It was proposed from the catalytic results and characterization (X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy) data that, the chloride ion is abstracted from adsorbed CCl 4 by Ag to form CCl 3 and CCl 2 radicals and silver chloride (AgCl), and meanwhile the dehydrogenation of methanol over Ag domains intrigues initial active Ag-H species and formaldehyde (HCHO): then the CCl 3 and CCl 2 radicals are combined with Ag-H to generate reaction products (CHCl 3 , and CH 2 Cl 2 ) and Ag, and the dehydrogenated product HCHO facilitates the regeneration of formed AgCl to Ag with formation of carbon monoxide and hydrogen chloride. Th

We have previously shown that the use of ligand-free palladium employing Pd(OAc) 2 as catalyst precursor in the Heck reaction of aryl bromides is possible if low catalyst loadings, typically between 0.01-0.1 mol % are used. We have now tested this phenomenon, which we have dubbed " homeopathic" palladium, in biaryl formation using the Suzuki, the Negishi and the Kumada cross-coupling reactions. The Suzuki reaction of aryl bromides, both activated and deactivated, is possible using 0.02-0.05 mol % of Pd(OAc) 2 . In this reaction turnover frequencies up to 30,000 have been reached with activated substrates. Even aryl chlorides could be reacted if strongly electron-withdrawing substituents were present. The Negishi coupling with a variety of arylzinc halides was possible on aryl bromides containing electron-withdrawing substituents. The Kumada reaction only gave low yields of products under "homeopathic' conditions. https://www.lookchem.com/CASDataBase_100-10-7.htm

Amine borane and amine trideuterioborane adducts have been obtained in good yield by the crown-ether-catalysed reaction of R3N*HCl with NaBH4 and NaBD4 in ether.The absence of isotopic exchange in the reaction with NaBD4 is demonstrated by IR and 11B and 2H nuclear magnetic resonance spectra of Me3N*BD3.Key words: Boron; Hydride; Amine https://www.lookchem.com/CASDataBase_75-22-9.htm

Anti-1,2-phosphinyl alcohols 11 and their corresponding syn-isomers upon treatment with phosphorus trichloride and triethylamine give E and Z alkenes respectively, by an anti elimination. This is in marked contrast to the syn Horner-Wittig elimination of the corresponding 1,2-phosphinoyl alcohols. The 1,2-phosphinyl alcohols 11 were prepared by the reduction of 1,2-phosphinoyl alcohols with cerium(III) chloride/lithium aluminium hydride. The anti elimination is explained by the formation of a transient epi-phosphonium species. An unexpected E-selective Horner-Wittig elimination during the cerium(III) chloride/lithium aluminium hydride reduction of a 1,2-phosphinoyl alcohol in which the diphenylphosphinoyl group is adjacent to an aryl group is described. This led to the synthesis of the antimitotic agent E- combretastatin A-4. An alternative synthesis of the 1,2-phosphinyl alcohols from the corresponding phosphine-borane complex is also described. https://www.lookchem.com/CASDataBase_7