Visible-light-mediated direct C-H perfluoroalkylation of imidazoheterocycles

Recent Advances in Visible Light-Induced C-H Functionalization of Imidazo[1,2-a]pyridines

The imidazo[1,2-a]pyridine skeleton is widely present in many natural products and pharmaceutical agents. Due to its impressive and significant biological activities, such as analgesic, anti-tumor, antiosteoporosis, and anxiolytic properties, the derivatization of imidazo[1,2-a]pyridine skeleton has attracted widespread attention from chemists. In recent years, significant progress has been made in the derivatization of imidazo[1,2-a]pyridines through direct C-H functionalization, especially through visible light induction. This review highlights recent advances in visible light-induced C-H functionalization of imidazo[1,2-a]pyridines during the past ten years, and some reaction mechanisms are also discussed.

Photocatalytic C2-trifluoroethylation and perfluoroalkylation of 3-substituted indoles using fluoroalkyl halides

A photocatalytic reactivity platform for the C2-trifluoroethylation and perfluoroalkylation of 3-substituted indoles has been developed. A range of fluoroalkyl halides have been employed as radical precursors under mild, transition-metal-free conditions to access new (per)fluorinated chemical space featuring the indole substructure. This general protocol is also applicable to indole-containing peptides.

Review and Theoretical Analysis of Fluorinated Radicals in Direct CAr-H Functionalization of (Hetero)arenes

We highlight key contributions in the field of direct radical CAr- H (hetero)aromatic functionalization involving fluorinated radicals. A compilation of Functional Group Transfer Reagents and their diverse activation mechanisms leading to the release of radicals are discussed. The substrate scope for each radical is analyzed and classified into three categories according to the electronic properties of the substrates. Density functional theory computational analysis provides insights into the chemical reactivity of several fluorinated radicals through their electrophilicity and nucleophilicity parameters. Theoretical analysis of their reduction potentials also highlights the remarkable correlation between electrophilicity and oxidizing ability. It is also established that highly fluorinated radicals (e.g. ⋅OCF3) are capable of engaging in single-electron transfer (SET) processes rather than radical addition, which is in good agreement with experimental literature data. A reactivity scale, based on activation barrier of addition of these radicals to benzene is also elaborated using the high accuracy DLPNO-(U)CCSD(T) method.

Recent Developments in the Photochemical Synthesis of Functionalized Imidazopyridines

Imidazopyridines constitute one of the most important scaffolds in medicinal chemistry, as their skeleton could be found in a myriad of biologically active molecules. Although numerous strategies were elaborated for imidazopyridine preparation in the 2010s, novel eco-compatible synthetic approaches have emerged, conscious of climate change concerns. In this framework, photochemical methods have been promoted to conceive this heterocyclic motif over the last decade. This review covers the recently published works on synthesizing highly functionalized imidazopyridines by light induction.