Synthesis of Azetidines by Electrophilic Selenium-Induced Cyclization of Homoallylic Benzylamines.

Abstract Homoallyl benzylamines, prepared by allylation of the corresponding N-benzylimines, have been subjected to a selenium-induced cyclization under various conditions. At room temperature, the 4-exo and the 5-endo modes are competitive. In acctonitrile, the azetidine has been isolated as the major cyclization product, especially for homoallylamines derived from ketimines. With an excess of selenium reagent, 3-halopyrrolidines have been obtained.