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.