Intramolecular photoaddition reactions of (aminoalkyl)styrylamides

The photochemical reactions of a family of styrene-spacer-amine molecules in which the spacer consists of a rigid amide group in the middle of a flexible alkane chain have been investigated. Our study of the photophysics of these molecules has shown that the amide linker can facilitate intramolecular styrene-amine exciplex formation (J. Phys. Chem., in press). We report here the photochemical behavior of these amide-linked (aminoalkyl) styrylamides. Several tertiary amines are found to undergo regioselective alpha-C-H addition to the styrene double bond resulting in the formation of medium-ring iactams. A secondary amine undergoes N-H addition yielding an azalactam. The dependence of these reactions upon spacer structure, amine and amide substitution, and solvent polarity is discussed. (C) 1998 Elsevier Science S.A.