Effect of ring size on hydrogenation of 2-benzylidenecycloalkanols

Abstract

Reduction of 2-benzylidenecycloalkanones with lithium aluminium hydride gave the corresponding allylic cyclo-alkanols. After catalytic hydrogenation of these cyclic allylic alcohols, over a number of catalysts, five components were obtained by chromatography. In each case these were the hydrogenolysis product, the cis- and trans-2-(cyclohexylmethyl)cycloalkanols, and the cis- and trans-2-benzylcycloalkanols. The stereochemistry of the resulting, separated, epimeric cycloalkanols was determined by an n.m.r. method. The proportions of the products are interpreted in terms of stereochemical arguments.