Iron exchanged molybdophosphoric acid as an efficient heterogeneous catalyst for the synthesis of quinoxalines

An efficient iron exchanged molybdophosphoric acid catalyst is reported for the one pot tandem oxidative cyclization of α-hydroxy ketones with 1,2-diamines under aerobic conditions. The fresh and used catalysts were characterized by FT-infra red, X-ray diffraction and Raman spectroscopy. The characterization results reveal the presence of Keggin ion after the exchange of protons of MPA with iron for fresh and used catalysts. The preparation of the catalyst is simple and reusable with consistent activity. The catalyst has a practical advantage for the synthesis of quinoxalines. A plausible reaction mechanism is proposed for the synthesis of quinoxalines.

Graphical abstractA highly effective heterogeneous iron exchanged molybdophosphoric acid catalyst is reported for the one pot tandem oxidative cyclization of α-hydroxy ketones with 1,2-diamines under aerobic conditions. The plausible reaction mechanism is proposed based on reducible nature of Mo and Fe of the catalyst.Figure optionsDownload full-size imageDownload as PowerPoint slide