Recent Advances in Radical C−H Bond Functionalization of Imidazoheterocycles

Abstract

Direct CÀ H bond functionalization through radical pathway has emerged as a powerful and ideal strategy for the synthesis of organic compounds. This review provides an overview of recent developments in radical CÀ H functionalization of imidazoheterocycles such as imidazo[1,2-a] pyridine, benzo[d]imidazo[2,1-b]thiazole, imidazo [2,1-b]thiazole, imidazo[1,2-a]pyrimidine, imidazo [2,1-a]isoquinoline, imidazo[1,2-a]pyrazine and imidazo[1,2-a]quinoline using organic peroxides, photo/electric-induced protocols, iodine-based reagents, first-row transition metal catalysts (Fe, Mn, Ni and Cu) and inorganic oxidants/or

Recyclable Carbon Nitride Nanosheet‐Photocatalyzed Aminomethylation of Imidazo[1,2‐a]pyridines in Green Solvent

“…[ 4 ] Several commercially available drugs like necopidem, zolpidem, saripidem, and alpidem, contain the imidazo[1,2‐ a ]pyridine framework in their core structure. [ 5 ] Over the last decade, great achievements have been made on the direct C—H functionalization of imidazo[1,2‐ a ]pyridines. [ 6 ] For instance, the direct amination, [ 7 ] trifluoromethylation, [ 8 ] alkoxylation, [ 9 ] sulfenylation, [ 10 ] selenylation, [ 11 ] and halogenation [ 12 ] have been realized in the past few years.…”

Recent Developments in the Photochemical Synthesis of Functionalized Imidazopyridines

“…This skeleton was ignored for a long time in organic chemistry due to the underdevelopment of efficient methodologies for accessing highly functionalized molecules. In recent decades, the upturn of organometallic chemistry has emulated numerous synthetic strategies, particularly C–H functionalizations [ 11 , 12 , 13 , 14 , 15 ], condensations [ 16 ], or multicomponent reactions [ 17 ]. With awareness of the current environmental issues and the decrease in non-renewable sources, the development of straightforward and mild procedures using eco-friendly conditions is highly desirable.…”

Electrochemical Oxidative Regioselective C–H Cyanation of Imidazo[1,2-a]pyridines

“…There are a few examples concerning the C­(sp 2 )–H or C­(sp 3 )–H bond cyanation under the electrochemical conditions. , The electrocatalytic C–H activation is expected to play an important role in the direct functionalization of heterocyclic compounds. Imidazo­[1,2- a ]­pyridine is regarded as a kind of “drug bias” building block in medicinal chemistry; thus, the functional modification of this heterocycle is of great value in pharmaceutical synthesis, and a lot of remarkable works were developed in this area . In continuation of our long-standing interest in the selective direct C–H bond functionalization of imidazo­[1,2- a ]­pyridines, as well as on electrochemical synthesis, herein we want to describe an electrochemical oxidative C–H cyanation of imidazo­[1,2- a ]­pyridines using TMSCN as the cyano source to synthesize C3 cyanated products (Scheme f).…”