Oxidative addition of an alkyl halide to form a stable Cu(III) product

• 成果类型: Article
• 署名作者: Luo, Yongrui; Li, Yuli; Wu, Jian; Xue, Xiao-Song; Hartwig, John F.; Shen, Qilong
• 署名单位: Chinese Academy of Sciences; University of Chinese Academy of Sciences, CAS; Shanghai Institute of Organic Chemistry, CAS; University of California System; University of California Berkeley
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-14078
• DOI: 10.1126/science.adg9232
• 发表日期: 2023-09-08
• 页码: 1072-1079
• 关键词: mediated coupling reactions; c-n; copper; complexes; trifluoromethylation; organocuprate; intermediate; parameters; palladium; reduction

摘要

The step that cleaves the carbon-halogen bond in copper-catalyzed cross-coupling reactions remains ill defined because of the multiple redox manifolds available to copper and the instability of the highvalent copper product formed. We report the oxidative addition of a-haloacetonitrile to ionic and neutral copper(I) complexes to form previously elusive but here fully characterized copper(III) complexes. The stability of these complexes stems from the strong Cu-CF3 bond and the high barrier for C(CF3)-C(CH2CN) bond-forming reductive elimination. The mechanistic studies we performed suggest that oxidative addition to ionic and neutral copper(I) complexes proceeds by means of two different pathways: an S(N)2-type substitution to the ionic complex and a halogen-atom transfer to the neutral complex. We observed a pronounced ligand acceleration of the oxidative addition, which correlates with that observed in the copper-catalyzed couplings of azoles, amines, or alkynes with alkyl electrophiles.