[3+2] CYCLOADDITIONS OF AZIRIDINES MECHANISTICAL STUDIES

The reaction of 1-butyl-2-phenyl aziridine with dimethyl acetylenedica rboxylate under PET conditions yields four products, two isomeric pyrr olidines and the corresponding pyrroles as oxidation products from the pyrrolidines. The reaction of the aziridine with dimethyl maleate and dimethyl fumarate respectively under PET conditions yields pyrroles w ith retained stereochemistry of the dipolarophiles. The addition of ac rylonitrile to 1-butyl-trans-2,3-diphenyl aziridine under PET conditio ns leads to all four possible isomeric pyrrolidines whereas under dire ct photolysis only two pyrrolidines are formed. Based on these experim ental data the mechanism involving a radical cation will be discussed.