The formation of unsaturated diterpenoid alcohols from 1,4-glycols with N,N-dimethylformamide dimethyl acetal

Abstract

Treatment of the 1,4-diol ent-6β, 19-dihydroxykaur-16-ene with DMFDMA, quaternization of the resultant formamido–acetal with methyl iodide, followed by elimination and hydrolysis of the resultant formate gives the ent-19-hydroxykaur-5,16- and -6,16-dienes. Labelling studies show that the reaction proceeds with the elimination of a hydrogen atom that is trans to the axial C-6 alcohol.