N-Functionalization Of Benzimidazoles And Related Azaheterocycles

Benzimidazoles and related azaheterocycles widely exist in the structures of pesticides,medicines,and natural products.Among their derivatives,compounds bearing a N-(1-alkyl ester)moiety display important biological and pharmacological profiles.However,the synthesis of such 1-(N-heterocycle)alkyl esters is comparatively less investigated,mainly relies on the Markovnikov addition of azaheterocycles to vinyl esters.Therefore,development of new synthetic strategies to access this compound class is of great significance to medicinal and biological research fields.In this dissertation,a novel direct N-functionalization strategy of benzimidazoles and related azaheterocycles has been established using α-acyloxy sulfides under transition-metal-free conditions.The required α-acyloxy sulfide substrates were easily prepared via Pummerer rearrangement from corresponding sulfoxides and acyl chlorides.Then the reaction of these α-acyloxy sulfides by various nitrogen-containing heterocyclic compounds under certain conditions produced twenty-seven 1-(Nheterocycle)alkyl ester products.The structure of the product(1H-benzo[d]imidazoll-yl)methyl benzoate was further confirmed by X-ray crystallography.The present reaction features no use of transition metals,operational simplicity,and broad substrate scope,providing a facile access to a series of new N-(l-alkyl ester)modified benzimidazoles and related azaheterocycles from readily accessible substrates.