Copper-Catalyzed Oxidative C-H Bond Functionalization of N-Allylbenzamide for Regioselective C-N and C-O Bond Formation

Alkene 1,3-Difluorination via Transient Oxonium Intermediates

The 1,3-difunctionalization of unactivated alkenes is an under-explored transformation that leads to moieties that are otherwise challenging to prepare. Herein, we report a hypervalent iodine-mediated 1,3-difluorination of homoallylic (aryl) ethers to give unreported 1,3-difluoro-4-oxy groups with moderate to excellent diastereoselectivity. The transformation proceeds through a different mode of reactivity for 1,3-difunctionalization, in which a regioselective addition of fluoride opens a transiently formed oxonium intermediate to rearrange an alkyl chain. The optimized protocol is scalable and shown to proceed well with a variety of functional groups and substitution on the alkenyl chain, hence providing ready access to this fluorinated, conformationally controlled moiety.

Selective α-oxidation of amides via visible-light-driven iron catalysis

Hydroxyl radicals (˙OH) as one of the highly reactive species can react unselectively with a wide range of chemicals. The ˙OH radicals are typically generated under harsh conditions. Herein, we report hydroxyl radical-induced selective N-α C(sp3)-H bond oxidation of amides under greener and mild conditions via an Fe(NO3)3·9H2O catalyst inner sphere pathway upon irradiation with a 30 W blue LED light strip (λ = 455 nm) using NaBrO3 as the oxidant. This protocol exhibited high chemoselectivity and excellent functional group tolerance. A preliminary mechanism investigation demonstrated that the iron catalyst afforded hydroxyl radicals via the visible-light-induced homolysis (VLIH) of iron complexes followed by a hydrogen atom transfer (HAT) process to realize this transformation.

NHPI-Mediated Electrochemical α-Oxygenation of Amides to Benzimides

This report describes a mild electrochemical α-oxygenation of a wide range of linear and cyclic benzamides mediated by N-hydroxyphthalimide (NHPI) in an undivided cell using O₂ as the oxygen source and 2,4,6-trimethylpyridine perchlorate as an electrolyte. The radical scavenger experiment and the ¹⁸O labeling experiment were carried out, which indicated the involvement of a radical pathway and suggested O₂ as an oxygen source in the imides, respectively.

1,3-Difunctionalization of alkenes: state-of-the-art and future challenges

This review summarizes the advances in 1,3-difunctionalization of alkenes mediated by Pd-, Ni-, Fe-, and Cu-based catalysts, as well as under metal-free conditions, with an emphasis on the reaction mechanisms and factors governing regioselectivity.

Progress and prospects in copper-catalyzed C-H functionalization

Copper-catalyzed C-H functionalization is becoming a significant area in organic chemistry. Copper is now widely used as a catalyst in organic synthesis as it is inexpensive and not very toxic. Functionalization of C-H bonds to construct wide varieties of organic compounds has received much attention in recent times. This review focuses on the recent advances in Cu-catalyzed C-H functionalization and covers literature from 2018-2020.