2-Benzotriazolylaziridines and Their Reactions with Diethyl Acetylenedicarboxylate

1-Alkyl-2-benzotriazolylaziridines (3a,b and 8a−g) are synthesized by two routes utilizing a novel benzotriazolyl-substituted carbenoid or 1,2-dibromoethylbenzotriazole. Lithiation of 3b and 8e at the position a to benzotriazole and subsequent trapping with alkyl halides leads to the 1,2-dialkyl-2-benzotriazolylaziridine analogues 12 and 20. Compounds 3a and 3b react with acetylenedicarboxylic ester by C−C bond breaking to give pyrrole-3,4-dicarboxylic esters (14a,b). By contrast, compounds 8a−d and 20 react with acetylenedicarboxylic ester by C−N bond breaking and form pyrrole-2,3-dicarboxylic esters 18a−d and 21. Structures of each type of pyrroledicarboxylic ester are established by X-ray analysis.