A methodology for the preparation of 2-substituted-benzimidazole-3-oxides will be presented. This heterocycle motif has shown biological activity against some neglected tropical diseases (NTDs) and, as such, is a sought-after class of compounds. Using a one-pot two-step protocol, we have generated a library of more than 45 new compounds. Reactions are performed using microwave heating as a tool. Using this technology it is possible to heat reaction mixtures quickly, efficiently, and safely. Our approach offers a more sustainable alternative to that of previously reported routes; only water and ethanol being used as solvents. We have also developed a streamlined work-up process, allowing for facile isolation of the products without the need for liquid-liquid extraction or column chromatography. We have evaluated the methodology from a green chemistry perspective by means of different sustainability metrics, such as E-factor, CHEM21, EcoScale, Dozn, and Green Star. The results confirm an improvement in sustainability compared with previously reported methodologies to prepare similar compounds.

One-pot two-step synthesis of 2-substituted benzimidazole <i>N</i>-oxides and sustainability assessment using green chemistry metrics

ACS Fall 2021

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One-pot two-step synthesis of 2-substituted benzimidazole N-oxides and sustainability assessment using green chemistry metrics