Photocyclization of N‐Alkyl‐N‐(3‐aryl‐3‐butenyl) ureas. Hydrogen transfer via charge transfer exciplexes in alkene photochemistry

Abstract

Photolysis of N‐alkyl‐N‐(3‐aryl‐3‐butenyl) ureas (1) in acetonitrile gave cyclization products, 3‐aryl‐3‐methyl‐pyrrolidines, in good yields, whereas irradiation of 1 in methanol afforded methanol adducts as well as the cyclization products. Both the reactions are singlet reactions, and the cyclization is presumed to proceed via 1,6‐hydrogen transfer from exciplexes with charge transfer character.