Consecutive Cycloaddition/S_NAr/Reduction/Cyclization/Oxidation Sequences: A Copper-Catalyzed Multicomponent Synthesis of Fused N-Heterocycles

Abstract

A highly efficient multicomponent domino protocol has been developed for the synthesis of 5-phenyl-[1,2,3]triazolo[1,5-c]quinazolines from simple and readily available (E)-1-bromo-2-(2-nitrovinyl)benzenes, aldehydes, and sodium azide. This elegant domino process involved consecutive [3 + 2] cycloaddition, copper-catalyzed S(N)Ar, reduction, cyclization, and oxidation sequences. Notably, sodium azide acted as a dual nitrogen source in the construction of this novel fused N-heterocycle.

On Water Cu@g‐C3N4 Catalyzed Synthesis of NH‐1,2,3‐Triazoles via [2+3] Cycloadditions of Nitroolefins/Alkynes and Sodium Azide

“…Development of sustainable protocols for the synthesis of 1,2,3‐triazole scaffolds have emerged one of the thrust area of research for organic chemist due to their exclusive pharmaceutical, agrochemical, medicinal and many other applications . Several strategies have been reported for the synthesis of 1,2,3‐triazoles and Huisgen's dipolar cycloaddition of organic azides and alkynes is the most straightforward route . Subsequently, transition metal catalyzed alkyne‐azide cycloaddition (MAAC; M=Cu/Ag/Ru/Ir/Al) have been developed for the synthesis of 1,4 or 1,5‐disubstituted or 1,4,5‐trisubstituted triazoles .…”

Progress in the Synthesis of Fused 1,2,3‐Triazoles

“…Wu and group reported a highly efficient domino approach for the synthesis of 5‐phenyl‐[1,2,3]triazolo[1,5‐ c ]quinazoline derivatives 152 from aromatic aldehydes 151 , sodium azide and ( E )‐1‐bromo‐2‐(2‐nitrovinyl)benzenes 150 via cascade [3+2] cycloaddition, copper catalyzed S N Ar, reduction, cyclization and oxidation sequences (Scheme 46). [51] In ligand screening, L‐proline was found superior than DMEDA, TMEDA, 1,10‐phenanthroline, hydroxyl‐proline(trans) and DL‐pipecolic acid. Diverse electron rich, electron deficient and sterically hindered aryl substrates, and heteroaryl moieties such as thiophenyl, furyl and pyridinyl were successfully employed to afford fused products.…”

Copper‐Catalysed Multicomponent Syntheses of Heterocycles

“…A multicomponent domino process has been developed for the synthesis of 5‐phenyl‐[1,2,3]triazolo[1,5‐ c ]quinazolines from ( E )‐1‐bromo‐2‐(2‐nitrovinyl)benzenes, aldehydes and sodium azide via [3+2] cycloaddition, Cu‐catalysed S N Ar, reduction, cyclisation and oxidation sequences (Scheme ) . Here, NaN 3 acts as dual nitrogen source in the formation of two nitrogen heterocycles.…”