10065-72-2 Crucigasterins, New Polyunsaturated Amino Alcohols from the Mediterranean Tunicate Pseudodistoma crucigaster

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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

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100-64-1 On the Oxidation of Hydroxylamines with o -Iodoxybenzoic Acid (IBX)

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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
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100-44-7 The chemistry of cyclic carbaphosphazenes: The first observation of (R 2PN)(ClCN)2 (R=Cl, Ph) as a reagent for the conversion of alcohols to aldehydes, ketones, and alkyl chlorides

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The oxidation of nine primary and secondary alcohols to the corresponding aldehydes and ketones has been carried out under mild conditions and in good yields using the cyclocarbaphosphazenes (R 2 PN)(ClCN) 2 [R 2 P = Cl 2 P(1), Ph 2 P(2)] along with dimethylsulfoxide. While both the P-Cl and C-Cl bonds of the carbaphosphazene can in principle bring about the reaction, we observed an increased preference for the C-Cl bonds over the P-Cl bonds in the oxidation of alcohol. Blocking the reactive P site on the heterocyclic ring with the phenyl groups was found to reduce the yields of the oxidized products, while blocking the C- sites with diethylamino groups resulted in no reaction. In addition, along with DMF, the same cyclocarbaphosphazene has been found to be useful for the conversion of alcohols to alkyl chlorides. Copyright Taylor & Francis Group, LLC. https://www.lookchem.com/CASDataBase_100-44-7.htm
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75-75-2 Solvolyses of Secondary Sulfonates in Aqueous Ethanol and Acetone. Nonlinear mY Relationships due to Leaving Group and Medium Effects

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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...
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