Efficient synthesis of isoquinolines and pyridines via copper(i)-catalyzed multi-component reaction

Abstract

A wide range of 3-substituted isoquinolines, steroidal pyridines, 5,6-dihydrobenzo[f]isoquinolines and 1,6-naphthyridine were synthesized in good yield via a ligand-free copper-catalyzed three-component reaction of b-halovinyl/aryl aldehyde, aromatic/aliphatic terminal alkyne and tert-butylamine/ benzamidine in DMF under microwave irradiation. A catalyst-free reaction of ortho-alkynyl aryl/vinyl aldehydes with benzamidine under microwave irradiation also provided the 3-substituted isoquinoline and substituted pyridine derivatives in excellent yield.

Copper-Catalyzed Tandem Imine Formation, Sonogashira Coupling and Intramolecular Hydroamination: A Facile Synthesis of 3-Aryl-γ−carbolines

“…For example, Ag‐catalyzed tandem approach led to the synthesis of benzothienopyridines and benzofuropyridines by the reaction of o ‐alkynyl aldehydes with tert ‐butylamine . 3‐substituted isoquinolines, steroidal pyridines, 5,6‐dihydrobenzo[f]isoquinolines and 1,6‐naphthyridine were synthesized via a ligand‐free Cu‐catalyzed three component reaction of β‐halovinyl/aryl aldehyde, aromatic/aliphatic terminal alkyne and tert ‐butylamine/benzamidine in DMF under microwave irradiation . Furthermore, Chen and co‐workers have reported a microwave assisted one‐pot synthesis of isoquinolines, furopyridines, and thienopyridiens using Pd‐catalyzed sequential coupling‐imination‐annulation of bromoaryldehydes with terminal acetylenes and ammonium acetate …”

“…The exact mechanism for the formation of 3aa is not clearly understood. However, based on our control experiments and literature report, we suspect the multicomponent cascade reaction for the formation of 3‐aryl‐γ−carboline derivatives might be proceeding through the formation of imine adduct 4 a first followed by Cu‐catalyzed Sonogashira coupling and intramolecular electrophilic cyclization in tandem.…”

Ionic liquid catalyzed one‐pot multi‐component synthesis of fused pyridine derivatives: A strategy for green and sustainable chemistry

“…The literature investigation shows that limited procedures have been reported for the synthesis of fused pyridine analogs through Knoevenagel condensation followed by Michael addition using distinct types of recyclable catalysts. [29,30] even so, maximum reported methods are accompanying disadvantages like the use of toxic and use of costly and sometimes non-easily prepared catalysts. All these drawbacks of the reported approach promoted us to elaborate an ecofriendly and economical path for the synthesis of fused pyridine derivatives.…”

Concise Synthesis of Multisubstituted Isoquinolines from Pyridines by Regioselective Diels–Alder Reactions of 2‐Silyl‐3,4‐pyridynes

“…Therefore, the synthesis of isoquinolines has attracted considerable attention from both synthetic and biological perspectives. Although diverse synthetic methods for isoquinolines have been reported,3–6 most of them are based on the construction of a pyridine ring on benzene;4, 5a,c–i for example, the ring closure at the C1‐position of isoquinoline, in the Pictet–Spengler4 and Bischler–Napieralski reactions,4 and at the C4‐position, in the Pomeranz–Fritsch reaction4 (Figure 1). In contrast, the “reverse approach”, the construction of a benzene ring on pyridine, has not been investigated in detail 5b.…”