The reaction of (2S,S-S)-alpha-(1-hydroxyethyl)vinyl sulfoxide with alkyl radicals and tributyltin hydride gave the addilion-hydrogenation products with high diastereoselectivity, whereas (2R,S-S)-alpha-(-1-hydroxyethyl)vinyl sulfoxide gave no products under similar conditions. An important role of intramolecular hydrogen bonding for the diastereoselectivity as well as the reactivity toward alkyl radicals is discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.
Diastereoselective Radical Hydrogenation of α-(1-Hydroxyalkyl)vinyl Sulfoxides and Sulfones Controlled by Intramolecular Hydrogen Bonding
(S)-alpha-(1-hydroxyalkyl)vinyl sulfoxides (S)-5 with alkyl radicals and tributyltin hydride gave the addition-hydrogenation products with high diastereoselectivity, whereas the reaction with (R)-alpha-(1-hydroxyalkyl)vinyl sulfoxides (R)-5 resulted in complete recovery of the starting sulfoxides. Stereoselective intramolecular hydrogen bonding between the hydroxy group and the diastereotopic sulfonyl oxygen led to high