Dioxopyrrolines. XXXVI. [2 + 2] Photocycloaddition Reaction of4-Ethoxycarbonyl-5-phenyl-1H-pyrrole-2, 3-dione to Acyclic Olefins. Structural and Stereochemical Assignment of the Photocycloadducts

Abstract

The photocycloaddition of the dioxopyrroline 1 to olefins with electron donating substituents proceeded with regio-and stereo-selectivity to give the 7-substituted 2-azabicyclo [3.2.0] heptane-3, 4-diones 2 and 3, together with, in a few instances, the dihydropyridone 4. The stereochemistries of the [2 + 2] adducts were dependent on the nature of the olefins. Olefins carrying phenyl, vinyl, and alkyl substituents afforded the exo-adducts 2, while olefins carrying an O-substituent afforded the endo-adducts 3, predominantly. The structures of these cycloadducts were established by X-ray crystallographic analyses, chemical correlations, and spectroscopic means.