Tandem Amination/Cycloisomerization of Aryl Propargylic Alcohols with 2‐Aminopyridines as an Expedient Route to Imidazo[1,2‐a]pyridines

Abstract

A new tandem route leading to imidazo[1,2-a]pyridines has been explored through the direct amination of aryl propargylic alcohols with 2-aminopyridines and their subsequent intramolecular cycloisomerization. A ZnCl 2 /CuCl system has

One-Pot Synthesis of 2-Phenylimidazo[1,2-α]pyridines from Acetophenone, [Bmim]Br3 and 2-Aminopyridine under Solvent-Free Conditions

“…Various methods have been reported for the synthesis of substituted imidazo[1,2-a]pyridines. The most important approaches embrace [ 20 ]: (1) condensation of 2-aminopyridine with α-halocarbonyl compounds [ 21 , 22 , 23 , 24 ], (2) one-pot condensations of isocyanide, aldehydes, and 2-aminopyridines [ 25 , 26 , 27 ], and (3) three-component reactions of 2-aminopyridines, aldehydes, and alkynes [ 28 , 29 , 30 ]. Although new methods are being published continuously, the synthesis of imidazo[1,2-α]pyridines using 2-aminopyridines with α-haloketones and α-haloaldehydes is still the most popular [ 31 , 32 ].…”

Heterogeneous Copper‐Catalyzed Cascade Three‐Component Reaction Towards Imidazo[1,2‐a]pyridines: Efficient and Practical One‐Pot Synthesis of Alpidem

“…Subsequent protonation of the C–Cu bond in intermediate E forms intermediate F and regenerates MCM‐41‐2N−Cu(OTf) 2 . Finally, intermediate F undergoes isomerization via a 1,3‐H‐shift to afford imidazo[1,2‐ a ]pyridine 4 …”

Recent synthetic scenario on imidazo[1,2-a]pyridines chemical intermediate

“…Recently, silver-mediated synthesis of imidazo[1,2-a]pyridines [45] 1.68 through C-H/N-H oxidative cross-coupling/cyclization between 2-aminopyridines 1.23 and terminal alkynes 1.67 (Scheme 13) was reported by Lei et al…”