Selective Synthesis of trans- and cis-p-Mentha-1,8-dien-5-ol from trans-Verbenol

Article abstract of DOI:10.1055/s-1988-27771

A selective synthesis of both trans- and cis-p-mentha-1,8-dien-5-ol from trans-verbenol is described.The sequence leading to trans-p-mentha-1,8-dien-5-ol consists of cleavage of the cyclobutane ring of pinene with N-bromosuccinimide in acetone to give the acetonide of 6-bromo-trans-p-menthene-5,8-diol, hydrodebromination with lithium aluminum hydride, and acidic treatment of the resultant acetonide of trans-p-menthene-5,8-diol. cis-p-Mentha-1,8-dien-5-ol is obtained by Swern oxidation of the trans-isomer and reduction of the resultant ketone with lithium tri-sec-butylborohydride.Acidic treatment of the acetonide of cis-p-menthene-5,8-diol (obtained from cis-verbenol) gives exclusively p-mentha-1(7),2-dien-8-ol.