An unusual ring contraction in the formation of N-nitrosohexamethyleneimine and N-nitrosopiperidine from tolazamide.

The previously reported reaction of tolazamide with nitrite, under physiological conditions, to form N-nitrosohexamethyleneimine and surprisingly, N-nitrosopiperidine was confirmed. By using the six-membered ring analogue of tolazamide, 1-(piperidyl)-3-(p-tolylsulfonyl)urea, which yields the corresponding N-nitrosopiperidine and N-nitrosopyrrolidine, the present study shows that an unusual ring contraction occurs, excising the carbon alpha to the nitrogen.