Stereochemical studies on isomeric 1,2,5-trimethyl-4-phenylpiperidin-4-ols : reactions with acyl chlorides and thionyl chloride

Abstract

The acylation of some isomeric 2,5-dimethyl-4-phenylpiperidin-4-ols is described and ¹H n.m.r. features of the resultant esters are interpreted in terms of configuration and preferred conformation. Evidence of stereochemistry is also provided by the differing behaviour of 1,t-2,t-5- and 1,t-2,c-5-trimethyl-4-phenylpiperidin-r-4-ol towards thionyl chloride; both are dehydrated but the former gives a single product whereas the latter gives a binary mixture of alkenes. The analgesic activities of alcohols and esters related to trimeperidine in mice, as assessed by the hot-plate test, are reported.