Transition metal-free C–H activation of heteroarenes: an overview (2018–2022)

Visible light-driven C–H arylation of heteroarenes with aryl diazonium salts in water catalyzed by a Z-scheme CuInS2/K-C3N4 heterojunction

“…[1][2][3] As a result, substantial efforts have been devoted to developing efficient methods for their expedient synthesis. 4 Traditionally, arylated heteroarenes are prepared by the Suzuki reaction using aromatic halides and aryl organoboron reagents as starting materials. 5,6 These methods are very effective and widely used in academia and industry.…”

A solvent-free mechanochemical electrophilic C–H thiocyanation of indoles and imidazo[1,2-a]pyridines using a cost-effective combination of N-chlorosuccinimide-NaSCN and tandem C–C and C–S bond formation

“…34 Palladium-catalyzed synthesis of 3-thiocyanatoindoles assisted by NBS was reported by Hu et al 35 The concept of metal-free C-H functionalization stands at the forefront of organic chemistry, introducing a paradigm shift in the manipulation and derivatization of organic molecules. 37 This approach facilitates the direct activation and modification of carbon-hydrogen (C-H) bonds, without relying on the traditional use of transition metal catalysts, which have long been the primary driving force behind C-H activation. The advent of metal-free C-H functionalization has ushered in a new era in synthetic chemistry, presenting environment-friendly, sustainable, and economically feasible routes for crafting intricate organic compounds.…”