endo-6-(Hydroxymethyl)bicyclo[3.1.0]hept-3-en-2-one esters and the photochemical challenge: [2+2] cycloaddition versus skeletal rearrangement

Abstract The photochemical reactivity of enantiomerically pure bicyclo[3.1.0]hept-3-en-2-ones has been examined to determine whether a [2+2] cycloaddition with an alkene could be achieved without interference from a photochemically induced skeletal rearrangement. The formation of a tricyclo[5.2.0.0 2,5 ]nonan-6-one was indeed the major pathway, exclusively providing the cis - anti - cis isomer. However, the formation of norbornenones was also observed, as was stereochemical scrambling at C6 in the starting material.