PHOTOCHEMICAL DIMERIZATION IN SOLUTION OF ARYLACRYLONITRILE DERIVATIVES

The photochemical irradiation of acrylonitrile derivatives bearing eit her aromatic or heteroaromatic rings as substituents on C-3 gives dime ric products. The reactions were carried out in acetonitrile in the pr esence of benzophenone as sensitizer. The most abundant dimer showed a structure similar to dimeric compounds isolated in Caribbean sponges showing antimicrobial activity. The regiochemical control in the forma tion of the dimers can be rationalised considering the overlap of the frontier orbitals involved in the reaction. The stereochemistry can be explained considering the heat of formation of the dimers the most st able dimers are formed. (C) 1997 Elsevier Science Ltd.