Direct Organocatalytic Chemoselective Synthesis of Pharmaceutically Active 1,2,3-Triazoles and 4,5′-Bitriazoles

Carbonyl-containing 1,4,5-trisubstituted- and 1,4-disubstituted-1,2,3-triazoles are well-known for their wide range of applications in pharmaceutical and medicinal chemistry, but their high-yielding metal-free synthesis has always remained challenging, as no comprehensive protocol has been outlined to date. Owing to their structural and medicinal importance, herein, we synthesized various carbonyl-containing 1,4,5-trisubstituted- and 1,4-disubstituted-1,2,3-triazoles and unsymmetrical 4,5′-bitriazoles with high yields and chemo-/regioselectivity from the library of 2,4-diketoesters and azides in a sequential one-pot manner through the combination of organocatalytic enolization, in situ [3 + 2]-cycloaddition, and hydrolysis reactions. The commercial availability of the starting materials/catalysts, diverse substrate scope, performance in a one-pot manner, chemo-/regioselectivity of organo-click reaction, quick synthesis of unsymmetrical 4,5′-bitriazoles, a large number of synthetic applications, and numerous medicinal applications of carbonyl-containing 1,2,3-triazoles are the key attractions of this metal-free organo-click work.