Preraration and Photolysis of 1-Heterosubstitute 1-(1-Alkenyl)benzotriazoles

A Peterson olefination reaction involving 1-trimethylsilanyl-methyl1H-benzotriazole and either adamantanone or acetone, in the presence of n-butyllithium, is used to prepare 1-adamantylidenemethyl- 1H-benzotriazole and 1-(2-methylpropenyl)-1H-benzotriazole respectively. Further treatment of these compounds with n-butyllithium and an electrophile affords a variety of 1-heterosubstituted 1-(1-alkenyl)benzotriazoles. Photolysis of the latter compounds yields products from three competing pathways: cyclisation with C-C bond formation, cyclisation with C-S bond formation and halogen atom transfer