172923-77-2 New strategy for the total synthesis of macrosphelides A and B based on ring-closing metathesis

(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

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726-18-1 Electrophilic alkylations in neutral aqueous or alcoholic solutions

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
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102-82-9 Selective Synthesis of Secondary and Tertiary Amines by Reductive N-Alkylation of Nitriles and N-Alkylation of Amines and Ammonium Formate Catalyzed by Ruthenium Complex

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
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1023-17-2 Syntheses, structures, and catalytic activity in Friedel–Crafts acylations of substituted tetramethylcyclopentadienyl molybdenum carbonyl complexes

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
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