Aspects of green chemistry toward synthesis of benzazoles and quinoxalines: Bovine serum albumin-water system for C-N/C-S bond formation

In this report, a biocatalytic divergent approach of therapeutically important five-membered benzazole heterocyclic compounds such as benzothiazoles and benzimidazoles has been described wherein Bovine serum albumin (BSA) and water play cooperative role for oxidative cyclo-condensation reaction between 2-mercapto/amino anilines and aromatic aldehydes under air at room temperature. Further, this green strategy also extended for the synthesis of privileged and biologically important six membered quinoxalines, 2-phenylimidazo [1,2-a]pyridine and benzo[d]imidazo[2,1-b]thiazoles. Moreover, the present biocatalytic protocol for the synthesis of such five- and six-membered heterocyclic compounds also have the added benefits of high atom economy, operational simplicity, excellent yields, recyclability (up to four cycles), and gram scalability.

Automated summary

This report describes a biocatalytic divergent approach for the synthesis of therapeutically important five-membered benzazole heterocyclic compounds, including benzothiazoles and benzimidazoles, as well as some biologically important six-membered heterocyclic compounds. The green strategy presented here offers high atom economy, operational simplicity, excellent yields, recyclability for up to four cycles, and scalability to gram quantities.