Direct Alkylation of Dianions of Cyclic ?-Diketones. A General Synthesis of 4-Substituted Cyclopentane-1,3-diones

Abstract
Intramolecular photochemical [2+2] cyclo-additions between enolised cyclopentane-1,3-diones and alkenes, provide a novel entry to tricyclic ring systems (viz 1) suitably functionalised for Grob fragmentation to the bicyclo [3,2,1] octane ring system (2) found in several important natural terpenoids.1