Rapid Construction of an Imidazo[4,5-b]pyridine Skeleton from 2-Chloro-3-nitropyridine via Tandem Reaction in H₂O-IPA Medium

Abstract

A highly efficient, clean, and simple procedure for the synthesis of a privilege imidazo[4,5- b ]pyridine scaffold from 2-chloro-3-nitropyridine in combination with environmentally benign H 2 O-IPA as a green solvent is presented. The scope of the novel method has been demonstrated through the tandem sequence of S N Ar reaction with substituted primary amines followed by the in situ nitro group reduction and subsequent heteroannulation with substituted aromatic aldehydes to obtain functionalized imidazo[4,5- b ]pyridines with only one chromatographic purification step. The synthesis pathway appears to be green, simple, and superior compared with other already reported procedures, with the high abundance of reagents and great ability in expanding the structural diversity.

Annelated Aminoimidazoles in Synthesis of Imidazo[4,5‐b]pyridines

“…As starting materials for this method are readily available, a combinatorial approach was developed allowing production of numerous compounds featuring imidazopyridine scaffolds . As demand for eco‐friendly method of synthesis is growing, green chemistry methods are elaborated …”

“…[9] As demand for eco-friendly method of synthesis is growing, green chemistry methods are elaborated. [10] The other alternative is closure of the pyridine ring with 1,3 -dicarbonyl compounds or their synthetic equivalents. Such compounds, for example, acetaldehyde, acrolein, 2-chloroacrylonitrile, methyl vinyl ketone, acetoacetic ester, etc.…”

On water catalyst-free synthesis of benzo[d]imidazo[2,1-b] thiazoles and novel N-alkylated 2-aminobenzo[d]oxazoles under microwave irradiation

“…This synthetic methodology was found to offer several advantages in comparison to the already reported synthesis protocols, such as excellent yields with high purity, avoidance of toxic transition-metal catalysts, a broad substrate scope, and green and economical process resulting from the use of a combination of H 2 O-IPA with MW irradiation. In a continuation of our quest to develop new synthetic methodologies using sustainable chemistry, [47][48][49][50] we developed in the currently described work a simple and facile procedure for the transition-metal-free synthesis of benzo…”

Synthesis of New 2‐(Pyridin‐4‐yl)‐1H‐imidazo[4,5‐b]pyridine Derivatives: In vitro Antibacterial and In silico Screening

“…Therefore, we made a substantial number of efforts to design, synthesize and identify new lead compounds as antibacterial compounds with novel structures containing (pyridin-4-yl)-1H-imidazo [4,5-b] pyridine as core moiety. As part of our research we describe here synthetic procedure for the synthesis of different (pyridin-4-yl)-1H-imidazo[4,5-b]pyridine [21]…”

“…Therefore, we made a substantial number of efforts to design, synthesize and identify new lead compounds as antibacterial compounds with novel structures containing (pyridin‐4‐yl)‐1H‐imidazo[4,5‐ b ] pyridine as core moiety. As part of our research we describe here synthetic procedure for the synthesis of different (pyridin‐4‐yl)‐1H‐imidazo[4,5‐ b ]pyridine [21] entities and perform in vitro antibacterial evaluation with Structure Activity Relationship (SAR) studies. By changing the different organic substrates at hydroxy centre of 2‐(pyridin‐4‐yl)‐1H‐imidazo[4,5‐ b ] pyridine‐7‐carboxylic acid (5) and 2‐(pyridin‐4‐yl)‐1H‐imidazo[4,5‐b] pyridine‐7‐carbaldehyde (7) antibacterial potency can vary.…”