Electrophile-Initiated Ring-Opening Reactions of 2-Methylene-6,6-dimethylbicyclohexanes. New Methodology for the Synthesis of Highly Functionalized 1,2,3-Trisubstituted Cyclopentenes

Article abstract of DOI:10.1021/jo00160a028

A pair of 1-substituted 2-methylene-6,6-dimethylbicyclo<3.1.0>hexanes has been determined to undergo smooth cyclopropane ring opening with formation of 1,2,3-trisubstituted cyclopentenes in the presence of electrophilic or free radical agents.High optical purity can be incorporated into these products, starting with the readily available l-menthyl 6,6-dimethyl-2-oxobicyclo<3.1.0>hexane-1-carboxylate, the two diastereomers of which are chromatographically separable.Through suitable chemical correlation, the absolute configurations of the various enantiomers have beenmade known.Finally, a scheme for transforming the cyclopentenes to 1,1,2,3-tetrasubstituted cyclopentanes as a necessary prelude to a synthesis of retigeranic acid is detailed.