ABSTRACT: The stereochemical course of the deamination of cis-2,3-dimethylaziridine by nitrosyl chloride was investigated at the QCISD/6-31G(d) level. Calculations reveal that the reaction takes place in two steps. In the first step, the reactants form a pre-reactive complex, followed by a spiro-type bicyclic transition state, which on dissociative cycloelimination gives the N-nitrosoaziridine intermediate. In the second step, this intermediate undergoes cycloreversion through a slightly asynchronous concerted transition state to form an alkene with the same stereochemistry, which is in total agreement with experiment. In the whole reaction, the denitrosation step is found to be rate-determining. For comparison, geometry optimizations and energies were also obtained at the B3LYP/6-31
