Sequential decarboxylative azide-alkyne cycloaddition and dehydrogenative coupling reactions: one-pot synthesis of polycyclic fused triazoles

Decarboxylative click cycloaddition: an emerging strategy towards substituted 1,2,3-triazole derivatives

1,2,3-triazole is a vital structural motif of various drugs and therapeutic leads, as well as a linker for bioconjugation and molecular recognition. Cu-catalysed click cycloaddition of azides with terminal alkynes (CuAAc) is an important reaction to construct the triazole core. In recent years, various decarboxylative click strategies utilizing alkynoic acids as stable surrogates for low boiling or gaseous alkynes have been developed. For instance, propiolic acid, which is easy to transport, is a safe alternative for flammable gaseous acetylene. In this review article, we have covered the recent development in the decarboxylative click cycloaddition of alkynoic acids with azides leading to the synthesis of diversely substituted triazoles, including monosubstituted, 1,4-disubstituted and fully substituted 1,2,3-triazoles. Various aspects such as mechanistic insights and optimization conditions/role of catalyst are highlighted.

Controlled photorelease of alkynoic acids and their decarboxylative deprotection for copper-catalyzed azide/alkyne cycloaddition

A controlled photorelease of alkynoic acids from a photoremovable protecting group (PPG) facilitates their subsequent decarboxylation to deliver terminal alkynes for a Cu^I-catalyzed azide/alkyne cycloaddition.