Tandem organocatalyzed Knoevenagel condensation/1,3-dipolar cycloaddition towards highly functionalized fused 1,2,3-triazoles

Abstract

Facile synthesis of fused 1,2,3-triazoles by a proline-catalyzed reaction of an azido aldehyde and a nitroalkane is elaborated. The present tandem protocol proceeds via an organocatalytic Knoevenagel condensation of the azido aldehyde and nitroalkane followed by intramolecular azidenitroalkene cycloaddition. The functionalized bicyclic tri-azole is obtained by elimination of HNO2 from the cycloadduct. Application of this strategy enabled us to synthesize a range of functionalised 5-7 membered ring fused triazoles. The reaction calls for mild conditions, affords high yields, and results in good regiospecificity while displaying excellent substrate scope.