Dehydration studies of 8a-Methyldecahydronaphthalen-4a-ols

Abstract

The H₂SO₄-HOAc-Ac₂O-catalysed dehydration of the epimeric 8a-methyldecahydronaphthalen-4a- ols has been shown to occur regiospecifically without skeletal or methyl migration, by loss of a proton syn to the departing anionic moiety. The results are interpreted in terms of the intermediacy of a tight ion pair where the oxy anion acts as the base in the removal of the proton. The introduction of an electron-withdrawing substituent at Cl, syn to the 8a-methyl of 8a-methyl-trans-decahydronaphthalen-4a-ol, allows methyl migration to compete with 1,2-elimination.