Abstract: The non-α-position metabolites of nitrosamines play an important role in chemical carcinogenesis. Ab initio computations are carried out to study the reactivity of β- and γ-position metabolites of methylakylnitrosamines. Taking N-methyl-N-nitroso-2-(sulfate)ethylamine(Ⅰ), N-methyl-N-nitroso-2- (phosphate)ethylamine(Ⅱ), N-methyl- N-nitroso-2-(glucuronate)ethylamine(Ⅲ), N-methyl-N-nitroso-3- (sulfate)-propylamine (Ⅳ), N-methyl- N-nitroso-3- (phosphate)propylamine (Ⅴ), and N-methyl-N-nitroso-3- (glucuronate)propylamine (Ⅵ) as models, we investigate their reactivity with the anchimeric assistant process of the N-nitroso groups. Full geometric structure optimization has been done for all reactants, intermediates and transition states. The activation energies, vibrational frequencies and IRC are also obtained. All computations are performed at RHF/6-31G(d) and MP2/6-31G(d) levels. The results show that the reactivity of the sulfates (Ⅰand Ⅳ) are obviously higher than those of the phosphates (Ⅱ and Ⅴ) and the glucuronates (Ⅲ and Ⅵ). And these data indicate that the anchimeric assistance is much more efficient when the leaving group is on the β-carbon than on the γ-carbon.

Key words: Alkylnitrosamines, Non-α-metabolites, Anchimeric assistance, Reactivity, Ab initio