Synthesis of 2-triazolyl-imidazo[1,2-a]pyridine through a one-pot three-component reaction using a nano copper oxide assisted click-catalyst

Abstract

The syntheses of 2-triazolyl imidazo[1,2-a]pyridine (8a–o) were accomplished through three component A³ coupling followed by 5-exo dig cyclisation by employing 1-alkyl-1,2,3-triazole-4-carbaldehyde, amidine and terminal alkynes using 5 mol% nanocopper oxide together with 10 mol% sodium ascorbate as a click-catalyst in ethanol at 70 °C. The present protocol was further utilized for the synthesis of 2-(2-triazolyl-imidazo[1,2-a]pyridin-3-yl)ethanol (9a–e). In addition, the molecular structure of 8c possesses a C–H⋯π interaction (H17b⋯C10) along with a peculiar supramolecular layered structure architecture. This protocol features ready recyclability of the catalyst, good yields and wide substrate scope. Moreover, the syntheses of triazolyl precursors (1-alkyl-1,2,3-triazol-4-yl)methanol (4a–f) have also been achieved through a nano copper oxide mediated click-catalyst in water at 70 °C.