(2-PHOTOSENSITIZED CYCLOADDITIONS OF MALEIC-ANHYDRIDE DERIVATIVES TO SELENOPHENE AND TELLUROPHENE DERIVATIVES(2))

The photoadditions of 2,3-dimethylmaleic anhydride to selenophene (C. Rivas, D. Pacheco, F. Vargas, J. Heterocycl. Chem. 17 (1980) 1151) and selenophthene (D. Pacheco, C. Rivas, F. Vargas, J. Heterocycl. Chem, 20 (1983) 1465) and of 2,3-dimethylmaleimide to selenophene and 3,4-di methylselenophene (C. Rivas, F. Vargas, A. Torrealba, D. Pacheco, R. M achado, G. Aguiar, Monatsh. Chem. 125 (1994) 1153) in benzophenone-pho tosensitized reactions have been carried out successfully in this labo ratory. This reaction has been extended to other methyl-substituted se lenophenes and, during the course of this investigation, it was observ ed that the compounds under study showed a somewhat different behaviou r from those mentioned above. The new photoproducts obtained are repor ted and an attempt is made to give a general view of the photochemical behaviour of methyl selenophenes. Furthermore, tellurophene and benzo (b)tellurophene were also tested as substrates for these (2+2) cycload dition reactions. (C) 1997 Elsevier Science S.A.