Preparation of thiochromans<i>via</i>thermal cyclization
作者:Anton W. Jensen、Joan Manczuk、David Nelson、Onalee Caswell、Steven A. Fleming
DOI:10.1002/jhet.5570370619
日期:2000.11
Formation of the thiochroman ringsystem is achieved by a two step synthesis that involves heating 3-thiophenyl-1-propanols or 4-thiophenyl-2-butanols in toluene with catalytic amounts of p-toluenesulfonic acid. The propanols are made by the addition of sulfur stabilized carbanions to styrene oxide, ethylene oxide, propylene oxide, and isobutylene oxide. The carbanions are generated by treatment of
Chloromethyl phenyl sulfides 3 underwent [4+ +2] type polar cyclo-additions with styrene, trans-stilbene, and phenylacetylene in the presence of stannicchloride to afford the thiochroman 4, 5 and thiochromen derivatives 6. Under the same reaction conditions, N-allyl-α-chloro-α-(phenylthio)acetamide (7) gave the intramolecular cycloaddition product 8.