The influence of stereochemistry on the dehydration of 5-Acetoxy-8a-methyldecahydronaphthalen-4a-ols

Abstract

The dehydration of (4α,5α,8aβ)- and (4aα,5α,8aα)-5-acetoxy-8a-methyldecahydronaphthalen-4a-ol with SOCl₂/pyridine and H₂SO₄/Ac₂O/HOAc is reported. For both substrates methyl migration does not compete with 1,2-elimination but for the (4aα,5α,8aα)-alcohol, spiran formation, resulting from migration of Cl to C4a, is observed on reaction with H₂SO₄/Ac₂O/HOAc. The influence of the relative stereochemistry at C4a, C5 and C8a on the course of reactions is discussed.