Tetrahedron

Regio-and stereoselective photocycloadditions of heterocyclic 2, 3-diones—Evidence for an unexpected 1, 2-aroyl migration

G Kollenz, E Terpetschnig, H Sterk, K Peters…

Index: Kollenz; Terpetschnig; Sterk; Peters Tetrahedron, 1999 , vol. 55, # 10 p. 2973 - 2984

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Citation Number: 18

Abstract

Photocyclization of the heterocyclic 2, 3-diones 1a-d with electron rich alkenes affords regio- and stereoselectively the 2+ 2 adducts 2, from 1b with benzophenone as photosensitizer also the Paterno-Büchi adduct 3 is obtained. Similarly, with phenylethyne the cycloadducts 4 are formed in moderate to low yields, in case of 1c the azepinone 6 is the only reaction product. Thermolysis of 4a generates the pyrono compound 5. Irradiation of the N- ...