Reactions of Diethoxytriphenylphosphorane with Diastereoisomeric 3-Methylcyclohexane-1,2-diols. Control of Regioselectivity by Methyl Substitution during Cyclodehydration and Rearrangement of 1,2-Diols

Article abstract of DOI:10.1021/jo00220a035

The diastereoisomeric 3-methylcyclohexane-trans-1,2-diols undergo cyclodehydration with diethoxytriphenylphosphorane (DTPP) to afford the cis- and trans-3-methylcyclohexene oxides.The ratio of cis and trans epoxides is best explained by assuming preferential phosphoranylation of the C1 hydroxyl group followed by " 3-exo-tet " alkoxide displacement of triphenylphosphine oxide.The diastereoisomers of 3-methylcyclohexane-cis-1,2-diol afford stable ? -dioxyphosphoranes when allowed to react with DTPP.These 1,3,2-dioxaphosphoranes were subjected to flash thermolysis ( <300 deg C ) conditions and afforded the isomeric 2- and 3-methylcyclohexanones via a 1,2-hydride shift.