First biocatalytic Groebke-Blackburn-Bienayme reaction to synthesize imidazo[1,2-a]pyridine derivatives using lipase enzyme

In this study, first biocatalytic synthesis of clinically important imidazo[1,2- a]pyridine based compounds has been achieved. The Candida antarctica lipase B (CALB) enzyme was found suitable to catalyze the Groebke-Blackburn-Bienayme (GBB) multicomponent reaction of substituted 2-aminopyridine, benzal-dehyde and isocyanides to synthesize imidazo[1,2-a]pyridine derivatives in very good yields. Further, CALB enzyme was immobilized on mesoporous silica and characterized using FT-IR, XRD, SEM-EDS and HR-TEM to use as a reusable catalyst in this transformation. The immobilized catalyst CALB@SiO2 displayed high catalytic efficiency up-to many cycles. In addition, preliminary mechanistic studies such as molecular docking and molecular dynamics (MD) simulation were performed which suggested that Thr40 and Ser105 residues are playing an important role in catalyzing the GBB-reaction. (C) 2020 Elsevier Ltd. All rights reserved.