Copper-Catalyzed Direct Oxidative C–H Functionalization of Unactivated Cycloalkanes into Cycloalkyl Benzo[b]phosphole Oxides

Abstract

The first simple and efficient Cu-catalyzed radical addition/cyclization of various unactivated cycloalkanes with diaryl(arylethynyl)-phosphine oxides has been developed, providing a general, one-step approach to construct a new class of important benzo[ b]phosphole oxides via sequential C-H functionalization along with two new C-C bond formations.

Copper‐Catalyzed Benzylic C—H Functionalization, Oxidation and Cyclization of Methylarenes: Direct Access to 2‐Arylbenzothiazoles

“…Based on these observations, a tentative mechanism for the product formation is proposed in Scheme . Initially, the tert ‐butoxyl radical is generated from DTBP . Then, the tert ‐butoxyl radical abstracts the hydrogen atom of toluene to afford benzyl radical A .…”

“…Initially, the tert ‐butoxyl radical is generated from DTBP . Then, the tert ‐butoxyl radical abstracts the hydrogen atom of toluene to afford benzyl radical A . A single‐electron transfer (SET) from A to copper(II) leads to cation B and copper(I), which can be oxidized to copper(II) for catalytic recycle by DTBP .…”

Progress and prospects in copper-catalyzed C–H functionalization

“…An efficient protocol towards cycloalkyl benzo[b]phosphole oxides 230 through Cu-catalyzed reaction between diaryl(arylethynyl)phosphine oxides 228 and cycloalkanes 229 was established. 98 This reaction was carried out at 140 C with ditert-butyl peroxide (DTBP) as benecial oxidant (Scheme 87). A wide variety of cycloalkanes such as cycloheptane, cyclodecane, cyclododecane, norbornane etc.…”

Recent Advances on Copper-Catalyzed C–C Bond Formation via C–H Functionalization

“…Mechanistic studies including kinetic isotope effect measurements as well as radical-scavenging experiments, suggest the intermediacy of radical species and the involvement of C-H bond cleavage at the cycloalkyl moiety in the rate-determining step. 40 Zhu and co-workers resorted to an aerobic CDC methodology to prepare -substituted esters of -amino acids from N-arylglycine esters and imidazo[1,2-a]pyridines. Importantly, the developed method showed high functional group tolerance and good yields were obtained under rather mild reaction conditions and considerable operational simplicity (Scheme 9).…”