Frustrated Lewis pairs in two-dimensional borocarbonitride for the facile synthesis of 3-aminoimidazo[1,2-α]pyridines using TMSCN as an isonitrile substitute

Abstract

Reusable catalysts are attractive alternatives to the metal-free catalysts accelerating the Groebke–Blackburn–Bienayme reaction for the efficient synthesis of imidazo[1,2-α]pyridines. Herein, we report the synthesis of a reusable defective borocarbonitride catalyst with Lewis acidic boron and Lewis basic nitrogen, which switches the nature of the catalyst from Lewis acid to a frustrated Lewis pair (FLP). Furthermore, FLPs catalyzed the Groebke–Blackburn–Bienayme-type one-pot multi-component (2-aminopyridine, aldehyde and trimethylsilyl cyanide) reaction to afford 3-aminoimidazo[1,2-α] pyridines. Moreover, FLPs were employed for the synthesis of fused heterocyclic compounds for the first time. The noteworthy features of this protocol are its short reaction time, wide functional group tolerance, good yields and catalyst recovery.