A vinylcyclobutane substrate designed as a cyclopropylcarbinyl radical probe

Abstract

Appending a spirocyclopropane linkage to bicyclo[3.2.0]hept-2-ene is achieved by selective kinetic cyclopropanation of 6-methylenebicyclo[3.2.0]hept-2-ene. The resultant vinylcyclobutane undergoes [1,3] migration as the dominant thermal process. A minor cyclopropylcarbinyl (CPC) rearrangement product clearly implicates a diradical transition structure. The presence and absence of other potential thermal products have enabled us to construct a detailed mechanistic proposal to account for all viable dynamic processes.