Chemo-, regio-, and stereoselective heterocyclization of sulfonamides and d-limonene with solvent interception

Abstract

A one-step catalyst-free synthesis of 3a,4,5,6,7,7a-hexahydro-1H-benzo[d]imidazoles combining pharmacologically active terpene and imidazoline motifs has been elaborated based on the NBS-induced reaction of arenesulfonamides with D-limonene as the first diene terpene, in acetonitrile under mild conditions (room temperature). The structure of the products was proved by 2D NMR techniques and, for most products, by X-ray analysis. The products are formed chemo-, regio-, and stereoselectively in good yields. Theoretical calculations are in excellent agreement with the proposed mechanism and could explain the high selectivity of the reaction.