Synthesis of the Cyclobutanone Core of Solanoeclepin A via Intramolecular Allene Butenolide Photocycloaddition.

The compact tricyclic substructure of solanoeclepin A containing the cyclobutanone ring was prepared by using as the key step a highly regioselective intramolecular [2 + 2]-photocycloaddition reaction between one of the π-bonds of an allene and the CC double bond of a butenolide.