Enzyme-mediated domino synthesis of 2-alkylbenzimidazoles in solvent-free system: A green route to heterocyclic compound

Solvent-free domino acylation/cyclization reactions between fatty acid esters and o-phenylenediamine mediated by immobilized lipase from Mucor miehei (MML) were found to be an efficient way in the synthesis of 2-alkylbenzimidazole. Compared with other substrates, methyl fatty acid esters with moderated chain length exhibited best activity with yield up to 95%. The mechanism of the domino process was clarified deeply through some detail experiments, including separation of intermediates. This efficient enzymatic domino process provides an attractive procedure for heterocyclic compound synthesis and could be regarded as a potential synthetic method in modern organic chemistry.