Recent synthetic methodologies for imidazo[1,5-a]pyridines and related heterocycles

Abstract

Imidazo[1,5-a]pyridine is a significant structural component of a huge number of agrochemicals and pharmaceuticals. The synthesis of imidazo[1,5-a]pyridine has been a subject of intense research for numerous decades. A large...

Electrochemical synthesis of CN-substituted imidazo[1,5-a]pyridines via a cascade process using NH4SCN as both an electrolyte and a non-trivial cyanating agent

“…[36][37][38][39][40] A number of methods have been reported for the synthesis of imidazo [1,5-a]pyridine derivatives via heterocyclization. 41,42 The strategy based on condensation of pyridine-2-carboxaldehydes with amines followed by decarboxylative C(sp 3 )-H amination has gained a widespread recognition in recent years. A variety of chemical oxidative systems were applied for imidazo [1,5-a]pyridine core construction from pyridine-2-carboxaldehydes and amines: Cu(II)/air, 43 Cu(I)/ air, 44 Cu(II)/I 2 /DTBP, 45 Cu-based MOF/air, 46,47 iodine, [48][49][50] I 2 / TBHP, 51 and MnO 2 52 (Scheme 2a).…”

Cu(I)-Catalyzed Three-Component Annulation for the Synthesis of 3-Acyl Imidazo[1, 5-a]Pyridines from 2-Pyridinyl-Substituted p-Quinone Methides, Terminal Alkynes, and TsN3 Using O2 as the Oxygen Source

“…The promising properties and applications of these molecules have always inspired organic chemists to establish some attractive synthetic routes for achieving those high-valued N -heterocyclic frameworks in the last few decades. However, a careful literature survey found that most conventional methods to achieve imidazo­[1,5- a ]­pyridines had limitations for the synthesis of 3-acyl imidazo­[1,5- a ]­pyridines . Furthermore, synthetic routes to 3-acyl imidazo­[1,5- a ]­pyridines, traditionally, include two methods, in which all the desired products achieved successfully by both strategies were afforded through multistep reactions employing 2-pyridinemethanamines as substrates under suitable conditions .…”

I2/H2O2 mediated synthesis and photophysical properties of imidazole-fused heterocycles via [4+1] cyclization approach

“…Both imidazo [1,5-a]pyridine and benzimidazole, which consist of an imidazole moiety fused to a hexacyclic aromatic ring, are important biologically active nitrogencontaining heterocycles. They are well-known for their medicinal use and material applications [1,2]. Imidazo [1,5-a]pyridine and benzimidazole derivatives possess various bioactivities, including antimicrobial, anthelmintic, antiviral, anticancer, and antihypertensive activities.…”