Reactions of the alkyl radical attached to the ring nitrogen of 2-phenylthio-indole, -benzimidazole and -uracil

Abstract

Alkyl radicals have been generated on the 1-N-alkyl group of 2-phenylthioindole, 2-phenylthiobenzimidazole and 6-phenylthiouracil derivatives. These N-alkyl radicals have been generated from the corresponding N-alkyl bromides by the action of triphenyltin hydride–azoisobutyronitrile, triphenyltincobaloxime or by the photolysis of the corresponding N-alkylcobaloxime. Reaction modes differ little with the method of radical generation except for the substantial formation of alkyl phenyl sulfide, a radical substitution product of the alkylcobaloximes, in the photolysis of the cobaloximes. The cobaloxime(II) species, which exists in the reaction system N-alkyl bromide–triphenyltincobaloxime, activates the phenylthio group for the radical substitution, and the lack of the tin hydride makes it possible for the reaction to occur at a higher concentration than the reaction with the hydride reagent.