Two homoallyl/cyclopropylalkyl rearrangements accompanying a Wolff–Kishner type reduction

Conceived as a model study for the enantioselective synthesis of the natural product (S)-bakuchiol, the deoxygenation of a recently described trishomoallyl alcohol was attempted using the Kabalka modification of the Wolff–Kishner method after prior oxidation of the alcohol to the ketone. However, an unprecedented succession of homoallyl/cyclopropyl ring closure and ring opening altered the carbon skeleton profoundly. The crucial intermediates are assumed to be radicals although carbanions cannot yet be definitely ruled out.