Facile synthesis of 1H-imidazo[1,2-b]pyrazoles via a sequential one-pot synthetic approach

Abstract

5-Aminopyrazole-4-carbonitrile and ethyl 5-aminopyrazole-4-carboxylate, as potential trifunctional building blocks are introduced in a facile, chemo- and regioselective multicomponent assembly of imidazo[1,2-b]pyrazoles via the Groebke–Blackburn–Bienaymé reaction (GBB reaction). Besides the synthetic elaboration of a green-compatible isocyanide-based access in three-component mode, we describe an operationally simple, one-pot two-step GBB protocol for the rapid construction of a 46 membered imidazo[1,2-b]pyrazole library with yields up to 83%.

Keywords

• Groebke–Blackburn–Bienaymé reaction
• 1H-imidazo[1,2-b]pyrazole
• isocyanide
• multicomponent reaction
• N-heterocycles