Direct Arylation of Imidazo[1,2-a]pyridine at C-3 with Aryl Iodides, Bromides, and Triflates via Copper(I)-Catalyzed C–H Bond Functionalization

Abstract

A convenient method for the copper(I)-catalyzed arylation of substituted imidazo[1,2-a]pyridine has been developed. This method is applicable to a variety of aryl electrophiles, including bromides, iodides, and triflates. It represents the first general process for C-3 arylation of substituted imidazo[1,2-a]pyridine by Cu(I) catalysis to construct various functionalized imidazo[1,2-a]pyridine core π-systems.

Copper‐Catalyzed Aerobic Oxidative NS Bond Functionalization for CS Bond Formation: Regio‐ and Stereoselective Synthesis of Sulfones and Thioethers

“…Although mesitylene 6 b could undergo the cross‐coupling reaction with low yield, the main byproducts were oxidative homocoupling isomers 15a. N‐Heterocycles, such as pyrimidine,15b 2‐phenylpyridine,15c and imidazo[1,2‐a]pyridine,15d could all be thiolated, regioselectively, in moderate yield. Furthermore, naphthols ( 7 f and 7 g ) were good coupling partners to afford the corresponding sulfenation products.…”

Functionalization of Imidazo[1,2‐a]pyridines by Means of Metal‐Catalyzed Cross‐Coupling Reactions

“…Recently, a new method for C–H activation of imidazo[1,2‐ a ]pyridines was reported by Jiang et al69 The best reaction conditions were CuI, phenanthroline, and t BuOK in DMF at 140 °C. Aryl iodides, bromides, and triflates were efficiently coupled with a variety of imidazo[1,2‐ a ]pyridines 106 .…”

Unconventional Reactivity with DABCO‐Bis(sulfur dioxide): C–H Bond Sulfenylation of Imidazopyridines

“…Although sulfenylation reactions of imidazo[1,2‐ a ]pyridines have been well developed, the corresponding sulfonylation reaction is more scarce despite the relevance of the sulfone moiety in pharmaceuticals and agrochemicals . During our initial studies of sulfonylation of C–H bonds by merging the reaction conditions of direct arylation of imidazo[1,2‐ a ]pyridine derivatives reported by Cao and the use of 1,4‐diazabicyclo[2.2.2]octane bis(sulfur dioxide) adduct [DABCO · (SO 2 ) 2 ], we came across an intriguing observation. The reaction between 2‐phenylimidazo[1,2‐ a ]pyridine 1 , iodobenzene 2 and DABCO · (SO 2 ) 2 in the presence of CuI, phenanthroline and t BuOK in DMF at 140 °C did not lead to the expected sulfonylated product 3 (Scheme , eq c).…”