Regiospecific 1,3-syn elimination in the acid-catalysed reaction of (4aa,5β,8aβ)-5-Acetoxy-8a-methyldecahydronaphthalen-4a-ol

Abstract

The H2SO4-HOAc-Ac2O catalysed dehydration of (4aα,5β,8aβ)-5-acetoxy-8a-methyldecahydronaphthalen-4a-ol(1) to give 8a-methyl-cis-l,2,3,4,6,7,8,8a-octahydronaphthalen-1-yl acetate (2) occursstereospecifically with loss of the hydrogen at C1. The reaction is interpreted in terms of the intermediacy of a tight ion pair in which there is sufficient mobility for the departing oxy-anion to act as base in the removal of the C1 α-proton.