Synthesis of the Bicyclo Ring Systems from 4-Allylcyclobutenones. Intramolecular Ketene/Alkene Cycloadditions

Article abstract of DOI:10.1021/jo00021a025

A general synthesis of bicyclo<3.2.0>heptenones from 4-allylcyclobutenones is described.The rearrangement is envisaged to involve an electrocyclic ring opening of the cyclobutenone and subsequent intramolecular 2 + 2 cycloaddition of the resulting vinylketene to the nonconjugated allylic alkene moiety.This method is particularly suitable for the synthesis of highly substituted derivatives since the regiochemistry of the substitution pattern is convenienty controlled.The scope of the rearrangement and the mechanism are discussed.