[2,3]-SIGMATROPIC REARRANGEMENT OF BETA-PHENYLSULFONYL PROPARGYLIC SULFENATES AS A METHOD FOR PREPARING 1,4-BIS(PHENYLSULFONYL)-1,3-BUTADIENES

Several beta-sulfoxy-substituted acetylenic carbinols were prepared by the addition of thiyl radicals and oxygen to conjugated enynes. The p roducts obtained are derived from thiyl radical attack at the olefinic bond to generate a propargylic radical. Capture of this radical by ox ygen followed by hydrogen transfer from thiophenol gives a hydroperoxi de intermediate, which undergoes oxygen transfer by both intra- and in termolecular pathways. The resultant beta-phenylsulfinyl propargylic a lcohols proved to be versatile intermediates for the preparation of se veral different classes of compounds. The [2,3]-sigmatropic sulfinate to sulfoxide rearrangement was found to give 1,4-bis(phenylsulfonyl)-1 ,3-butadienes, alpha,beta-unsaturated phenylsulfoxy ketones, and beta- phenylsulfonyl alpha-allenic sulfoxides' Oxidation of the sulfoxy moie ty to the sulfone followed by sulfinate formation with phenylsulfenyl chloride produces, after [2,3]-sigmatropic rearrangement, beta-phenyls ulfonyl alpha-allenic sulfoxides. In certain cases these allenes could be isolated, but were usually isomerized in situ and further oxidized to give 1,4-bis(phenylsulfonyl)-1,3-butadienes. The [2,3]-sigmatropic rearrangement of beta-phenyl-sulfinyl-substituted propargylic alcohol s proceeds by an entirely different course. With these systems, a doub le sigmatropic process occurs leading to the formation of vinyl sulfin ates which are readily hydrolyzed to give alpha,beta-unsaturated pheny lsulfoxy ketones.