C-N/N-N Bonds Formation to Access [1,2,3]Triazolopyrido[3,4-b]indoles and [1,2,3]Triazolo[1,5-a]pyridines

Abstract

A novel method devoid of transition metal and azide is introduced for the synthesis of [1,2,3]triazolopyrido[3,4-b]indoles, [1,2,3]triazolo[1,5-a]pyridines, and [1,2,3]triazolo[1,5-a]quinoline, achieving good to excellent yields. This approach was suitable for a diverse array of N-heterocyclic starting substrates, including monocyclic (pyridine carbaldehyde), bicyclic (quinoline carbaldehyde), and tricyclic (β-carboline carbaldehyde or ketone). The current domino strategy involves the one-pot synthesis of 1- or 3-formyl-β-carbolines, pyridine carbaldehyde, or quinoline carbaldehyde with tosylhydrazine in the presence of Cs₂CO₃, facilitating the creation of C-N and N-N bonds, as well as S-N cleavage. The prominent characteristics, such as easy reaction conditions, high yields, clean reactions, and simple purifications, render this approach a valuable addition to the synthesis of therapeutically significant heterocycles.

Keywords: Azide-free; Oxidant-free; Transition metal-free; [1,2,3]triazolo[1,5-a]pyridines; [1,2,3]triazolo[1,5-a]quinoline; [1,2,3]triazolopyrido[3,4-b]indoles.