E2 reactions of menthyl and neoisomenthyl Toluene-p-sulphonates

Abstract

The reaction of menthyl toluene-p-sulphonate (7) with potassium t-butoxide in benzene-dimethyl sulphoxide proceeds regiospecifically to afford trans-p-menth-2-ene (1). Mixtures of olefins are obtained when sodium ethoxide in ethanol, potassium t-butoxide in t-butyl alcohol or tetrabutylammonium bromide in acetone are used. Neoisomenthyl toluene-p-sulphonate (9), prepared by a stereospecific route from piperitone, affords mixtures of cis-p-menth-2-ene (2) and p-menth-3-ene(3) when treated with strong bases. The results are consistent with the concept of variable E2 transition states.