Polyoxometalate catalysts for the synthesis of N-heterocycles

Abstract

N-heterocycle compounds are the crucial scaffolds present in natural products, synthetic molecules, agricultural chemicals, and pharmaceuticals. Hence, the development of green catalytic systems for constructing N-heterocycles has been a focused topic in organic synthesis and industrial catalysis. Polyoxometalates (POMs) are polynuclear metal–oxygen clusters with structural diversity and physicochemical properties. POMs possess advantageous properties such as adjustable acidity, redox properties, high thermal stability, and non-toxic nature. Therefore, POMs have been widely investigated for their application in N-heterocycles synthesis and hold great potential for industrial applications. In this review, we summarized recent progress (mainly from 2010 to 2023) in the N-heterocycles synthesis catalyzed by heteropolyacids (HPAs), modified HPA catalysts, and transition metal-modified POMs. The synthesized N-heterocycles include pyrroles, indoles, pyridines, and benzodiazepines, among others. Furthermore, the prospects of POMs-based catalytic systems of N-heterocycles were also proposed.