Quasi-template effect: a tool for controlling stereochemistry in acyclic systems. Attempted stereoselective synthesis of α,α′-dimethoxystilbene
Abstract
Alkylation with methyl tosylate of stilbenediol dianion, prepared in the reaction of benzoin with a series of alkali-metal hydroxides in THF, gave (E)- and (Z)-α,α′-dimethoxystilbenes as the major products in most cases, the E:Z ratio of which varies from 0.4 to 5.0 depending upon the alkali-metal cation employed; the results are rationalized in the quasi-template effect in an acyclic system and the hard–soft ion principle.