Intramolecural Photocycloaddition on Dioxolenones: An Efficient Method for the Synthesis of Medium-sized Rings

Abstract

The intramolecular photocycloaddition of dioxolenones to simple olefins leads to the formation of sir-, seven-, and eight-membered rings in good yields.Asymmetric induction in the formation of cyclooetanes is described.The extension of the de Elayo to the ends of 0-ketoesters could significantly expand the utility of this reaction in synthesis, since the regioselective functionalization, i.e., alkylation and enolization, of the ketoesters is more straightforward than the same transformations in the 0-diketone Baldwln haa reported that dioxolenones, which can be regarded as the covalently restricted cis eool tautomers of the corresponding ketoesters, undergo intermolecular [2+2]-photochemical cycloaddition with alkenes, although with regiochemical outcomes which are difficult to predict.''We report herein that the intramolecular photoaddition of dioxolenones to alkenes results in the formation of six-, aeven-, and eight-membered rings, i.e, 1-3, in good yields with excellent regiochemical control.Scheme I