A Convenient one-pot Approach to the Synthesis of Novel Benzimidazole-Indole Molecular Hybrids as Benzazacamalexin Related Analogues.

Background: New benzazacamalexin-related analogues are synthesized in an easily accessible one-pot approach. The method is based on the reaction of indoles with in situ formed electrophilic N-alkoxycarbonylbenzimidazolium reagents. For the first time, their application for N-alkylation of the indole nitrogen atom is announced toward novel trisheterocyclic hybrids. The structure of newly obtained products was spectrally characterized by 1D and 2D-NMR, FTIR and HRMS spectral data. The current scientific research is based on the application of a convenient and efficient route for the preparation of various benzimidazoles. This approach is both straightforward and economical, utilizing readily accessible and affordable reagents leading to target compounds.

Objective: The synthesis of novel benzimidazole-indole molecular hybrids as benzazacamalexin related analogues.

Methods: A suitable in situ method has been successfully applied, using an α-amidoalkylation reaction of indoles with N,N-diacyliminium reagents derived from benzimidazoles and alkyl chloroformates.

Results: The reactions led to the obtaining of ten novel compounds (5a-e, 6a-e), including bromine and iodine-containing benzo-analogues on a gram-scale scope and yields ranging from 82% to 99%. For the first time the synthesis of indole tris-heterocycles (7a, b) through the reaction of N-alkylation of the indole nitrogen atom is announced giving another potential synthetic application of the N,N-dialkoxycarbonyl-5,6-dimethylbenzimidazolium adducts.

Conclusion: The structure of the newly synthesized products is spectrally analysed and proved.