The synthetic potential of phthalimide SET photochemistry

The authors' studies in the area of phthalimide photochemistry are discusse d in the context of the development of new methods for N-heterocycle synthe sis. Emphasis is given to reactions which are initiated by both intermolecu lar and intramolecular SET from silicon-containing electron donors to excit ed states of phthalimides and related maleimides and conjugated imides. The photoaddition and photo cyclization processes which ensue follow mechanist ic pathways, in which efficient desilylation of initially formed radical ca tion occurs to generate radical pair and biradical intermediates that serve as precursors of the products. Several examples that demonstrate the prepa rative potential of these reactions axe presented. These are taken from the authors' investigations of (1) phthalimido-alkylsilane photocyclization re actions, (2) azomethine ylide-forming excited-state processes of N-(trimeth ylsilylmethyl) phthalimide, and (3) photoaddition and photocyclization reac tions of phthalimide alpha -silyl ether, thioether, amine, and amide system s.