Decarboxylative radical allylation, vinylation, and cyanation

Abstract

Barton`s esters are very useful as precursors of alkyl and aminyl radicals from carboxylic acids via O-acyl thiohydroxamates and can be further applied not only for the introduction of synthetically useful functional groups such as a halide and nitrile but also for the formation of carbon-carbon bonds. In spite of their vast chemistry, Barton`s esters are too reactive and unstable at ambient temperature. We have developed new thiohydroxamate esters which are less reactive but more stable than Barton`s esters. We have studied decarboxylative carbon-carbon bond-forming reactions, allylation, vinylation, and cyanation, using O-acyl thiohydroxamates. It has been found that radical reactions of O-acyl thiohydroxamates with allyl sulfones, vinyl sulfones, and tosyl cyanide using V-40 as initiator in chlorobenzene at 110℃ furnish the corresponding allylation, vinylation, and cyanation products in good yields.