“…Therefore, various methods have been reported over the past 130 years for their synthesis that includes Skraup, 8 Doebnervon Miller, 9 Ptzinger, 10 Conrad-Limpach, 11 Combes 12 and Friedländer syntheses. 13 Recently, different catalysts such as CuCl, 14 CuBr, 15 Cu(OTf) 2 , 16 InCl 3 , 17 FeCl 3 , 18 Fe(OTf) 3 , 19 AgOTf, 20 AuCl 3 /CuBr, 21 NbCl 5 , 22 Yb(p) 3 , 23 CuI/La(OTf) 3 , 24 montmorillonite K-10 (ref. 25) for the A 3 -coupling reaction of alkyne, aldehyde and amine have been explored.…”