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

András Demjén; Márió Gyuris; János Wölfling; László G Puskás; Iván Kanizsai

doi:10.3762/bjoc.10.243

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

Beilstein J Org Chem. 2014 Oct 8:10:2338-44. doi: 10.3762/bjoc.10.243. eCollection 2014.

Authors

András Demjén¹, Márió Gyuris², János Wölfling³, László G Puskás⁴, Iván Kanizsai²

Affiliations

¹ AVIDIN Ltd., Alsó Kikötő sor 11, Szeged, H-6726, Hungary ; Department of Organic Chemistry, University of Szeged, Dóm tér 8, H-6720, Szeged, Hungary.
² AVIDIN Ltd., Alsó Kikötő sor 11, Szeged, H-6726, Hungary.
³ Department of Organic Chemistry, University of Szeged, Dóm tér 8, H-6720, Szeged, Hungary.
⁴ AVIDIN Ltd., Alsó Kikötő sor 11, Szeged, H-6726, Hungary ; AVICOR Ltd., Alsó Kikötő sor 11, Szeged, H-6726, Hungary.

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