1,3-Dithians. Part I. Ring contractions in the 1,3-dithian series

Abstract

1,3-Dithian-5-ols undergo stereospecific reactions with phosphourus oxychloride in pyridine to give 4-chloromethyl-1,3-dithiolans which hydrolyse readily to 4-hydroxymethyl-1,3-dithiolans. Similar ring contractions occur in displacement reactions of 2-phenyl-1,3-dithian-5-yl toluene-p-sulphonates and in reactions of 1,3-dithian-5-ols with phosphorus tribromide, although in the latter case the steric consequences are more complicated.