Highly regioselective C H bond functionalization of imidazo[1,2-a]pyridines with aryl halides catalyzed by Ru-arene complex

Palladium(II) catalyzed site-selective C-H olefination of imidazo[1,2-a]pyridines

Herein, we disclose an efficient Pd(II)-catalyzed site selective C8 alkenylation of imidazo[1,2-a]pyridines with electronically biased olefinic substrates. Notably, besides the presence of four C-H sites available, selective mono-alkenylation was achieved by N-chelation overriding O-chelation. The versatility and scalability of the catalysis enabled the selective late-stage functionalization of a marketed drug, zolimidine. Various substituted heteroaryl alkenes can be afforded with moderate to good yields with high C8 regioselectivity.

N-Heterocyclic carbene–palladium(ii)–1-methylimidazole complex catalyzed direct C–H bond arylation of imidazo[1,2-a]pyridines with aryl chlorides

NHC–Pd(ii) complex catalyzed C–H bond arylation of imidazo[1,2-a]pyridines with aryl chlorides was reported.

Cu(i)-catalyzed double C–H amination: synthesis of 2-iodo-imidazo[1,2-a]pyridines

An iodine/CuI mediated double oxidative C–H amination reaction has been developed for the synthesis of 2-iodo-imidazo[1,2-a]pyridines, which can serve as active pharmaceutical ingredients (API) of marketed drugs like saripidem and nicopidem.

Double head-to-tail direct arylation as a viable strategy towards the synthesis of the aza-analog of dihydrocyclopenta[hi]aceanthrylene – an intriguing antiaromatic heterocycle

Straightforwardly prepared head-to-tail bis-imidazo[1,2-a]pyridine displays antiaromaticity and no fluorescence.

Oxidative Cross-Coupling of sp(3)- and sp(2)-Hybridized C-H Bonds: Vanadium-Catalyzed Aminomethylation of Imidazo[1,2-a]pyridines

The vanadium-catalyzed oxidative coupling of substituted 2-arylimidiazo[1,2-a]pyridines to N-methylmorpholine oxide, which acts as both a coupling partner and an oxidant, has been achieved. This reaction was applied to various substituted imidiazo[1,2-a]pyridine and indole substrates, resulting in yields as high as 90%. Mechanistic investigations indicate that the reaction may proceed via a Mannich-type process. This work demonstrates how oxidative aminomethylation can be used as a useful method to introduce tertiary amines into heterocycles, thus providing an alternative method for conventional Mannich-type reactions.

Cu-Catalyzed selective C3-formylation of imidazo[1,2-a]pyridine C–H bonds with DMSO using molecular oxygen

Using the widely available DMSO as the formylation reagent under oxidative conditions, an efficient Cu-catalyzed C3-formylation reaction of imidazo [1,2-a]pyridine C–H bonds to directly generate structurally sophisticated 3-formyl imidazo[1,2-a]pyridine derivatives has been developed.

Advances in direct C–H arylation of 5,5- 6,5- and 6,6-fused-heterocycles containing heteroatoms (N, O, S)

This report aims to review the advances made in C–H arylation of 5,6, 6,6 and 5,5 fused-heterocyclic systems.

Vertically-expanded imidazo[1,2-a]pyridines and imidazo[1,5-a]pyridine via dehydrogenative coupling

The intramolecular dehydrogenative coupling mediated by potassium constitutes the general methodology leading to weakly emitting π-expanded heterocycles.

Palladium(ii)-catalyzed intermolecular oxidative C-3 alkenylations of imidazo[1,2-a]pyridines by substrate-contolled regioselective C–H functionalization

An efficient and highly regioselective palladium(ii)-catalyzed oxidative C-3 alkenylation of imidazo[1,2-a]pyridines with acrylate, acrylonitrile, or vinylarenes has been developed by using oxygen as an oxidant.