Synthesis of trans-Cycloalkenes via Enantioselective Cyclopropanation and Skeletal Rearrangement

An efficient one-pot two-step procedure for asymmetric synthesis of piperidine-fused trans-cycloalkenes is reported. The method comprises the initial enantioselective installation of another cyclopropane ring onto methylene­cyclo­pro­panes and the subsequent thermal skeletal rearrangement in which the installed and inherent cyclopropane rings are both opened. A concerted mechanism is proposed for the latter thermal rearrangement reaction together with a closed transition state model.