The photocycloadditions of 1, 4-dihydropyridines (DHPs) were achieved by using phenacylimidazoliums (PIms) as photosensitizers. Irradiation of DHPs 3a–g in the presence of PIms 1a–e and 2 performed an efficient formation of 3, 9-diazatetraasteranes in shorter times under a lower power lamp. The mechanism of photocycloaddition catalyzed by PIm was studied by laser flash photolysis and theoretical DFT computation. These time- ...
