Reactions of carbanions stabilised by adjacent nitrogen functions.

Abstract

The alpha-functionalisation via carbanion intermediates was effected on a series of nitrosamines. A number of alkylations were found to proceed efficiently in the case of dibenzylnitrosamine. Moderate yields were obtained in the methylation of 1-nitroso-4-phenylpiperazine. The carboxylation of this compound proved to proceed in higher yield than the alkylation. The carboxylation of 1-nitroso-pyrrolidine and 1-nitrosopiperidine was achieved in lower yield (27-28%). Optimum conditions for denitrosation were obtained by bubbling hydrogen chloride gas through the benzent: solution of the nitrosamine. The yields of the resultant amine hydrochlorides were consistently 80-90%. It was found that an amido group (i.e. in N, N-dibenzylbenzamide) like the nitroso group provides an activating influence for the lithiation alpha to nitrogen.