OXIDATION OF NITROSAMINES .1. FORMATION OF N-NITROSOIMMINIUM IONS THROUGH THE OXIDATIVE DECARBOXYLATION OF N-NITROSOPROLINE, N-NITROSOPIPECOLIC ACID, AND N-NITROSOSARCOSINE

αA-cetoxy-N-nitrosopyrrolidine (3),αa-cetoxy-N-nitrosopiperidine (7), and N-(αa-cetoxymethylene)-Nmethylnitrosamine (15), model compounds important in the study of nitrosamine metabolism, were synthesized from the corresponding nitrosamino acids. The nitrosamino acids were decarboxylated with lead tetraacetate to nitrosamino radicals, which were then oxidized to nitrosoimminium ions. Decarboxylation of nitrosoproline gave the solvolysis product 3 exclusively; nitrososarcosine gave the expected a-cetoxy compound, but dimethylnitrosamine was also obtained. Nitrosopipecolic acid gave the following compounds, with the relative yields in parentheses: N-nitroso-1,2,3,4-tetrahydropyridine (8,10.6%), N-nitroso-1,2,3,6-tetrahydropyridine (9,5.7%), N-nitroso-a-acetoxypiperidine (7, 33%), N-nitroso-cis-2,3-diacetoxypiperidine (10, 22%), N-nitrosotrans-2,3-diacetoxypiperidine (11,28%), N-nitroso-4-acetoxy-1,2,3,4-tetrahydropyridme (13, >1%). The product distribution from the decarboxylation experiments is attributed to the stability of the nitrosoimminium ions. © 1979, American Chemical Society. All rights reserved.