亲爱的研友该休息了!由于当前在线用户较少,发布求助请尽量完整地填写文献信息,科研通机器人24小时在线,伴您度过漫漫科研夜!身体可是革命的本钱,早点休息,好梦!

Mechanism of Cobalt(II) Porphyrin-Catalyzed C–H Amination with Organic Azides: Radical Nature and H-Atom Abstraction Ability of the Key Cobalt(III)–Nitrene Intermediates

化学 硝基苯 光化学 激进的 配体(生物化学) 叠氮化物 氢原子萃取 电子顺磁共振 胺化 催化作用 有机化学 核磁共振 生物化学 物理 受体
作者
Volodymyr Lyaskovskyy,Alma I. Olivos Suarez,Hongjian Lu,Huiling Jiang,X. Peter Zhang,Bas de Bruin
出处
期刊:Journal of the American Chemical Society [American Chemical Society]
卷期号:133 (31): 12264-12273 被引量:346
标识
DOI:10.1021/ja204800a
摘要

The mechanism of cobalt(II) porphyrin-catalyzed benzylic C–H bond amination of ethylbenzene, toluene, and 1,2,3,4-tetrahydronaphthalene (tetralin) using a series of different organic azides [N3C(O)OMe, N3SO2Ph, N3C(O)Ph, and N3P(O)(OMe)2] as nitrene sources was studied by means of density functional theory (DFT) calculations and electron paramagnetic resonance (EPR) spectroscopy. The DFT computational study revealed a stepwise radical process involving coordination of the azide to the metal center followed by elimination of dinitrogen to produce unusual "nitrene radical" intermediates (por)CoIII–N•Y (4) [Y = −C(O)OMe, −SO2Ph, −C(O)Ph, −P(O)(OMe)2]. Formation of these nitrene radical ligand complexes is exothermic, predicting that the nitrene radical ligand complexes should be detectable species in the absence of other reacting substrates. In good agreement with the DFT calculations, isotropic solution EPR signals with g values characteristic of ligand-based radicals were detected experimentally from (por)Co complexes in the presence of excess organic azide in benzene. They are best described as nitrene radical anion ligand complexes (por)CoIII–N•Y, which have their unpaired spin density located almost entirely on the nitrogen atom of the nitrene moiety. These key cobalt(III)–nitrene radical intermediates readily abstract a hydrogen atom from a benzylic position of the organic substrate to form the intermediate species 5, which are close-contact pairs of the thus-formed organic radicals R′• and the cobalt(III)–amido complexes (por)CoIII–NHY ({R′•···(por)CoIII–NHY}). These close-contact pairs readily collapse in a virtually barrierless fashion (via transition state TS3) to produce the cobalt(II)–amine complexes (por)CoII–NHYR′, which dissociate to afford the desired amine products NHYR′ (6) with regeneration of the (por)Co catalyst. Alternatively, the close-contact pairs {R′•···(por)CoIII–NHY} 5 may undergo β-hydrogen-atom abstraction from the benzylic radical R′• by (por)CoIII–NHY (via TS4) to form the corresponding olefin and (por)CoIII–NH2Y, which dissociates to give Y–NH2. This process for the formation of olefin and Y–NH2 byproducts is also essentially barrierless and should compete with the collapse of 5 via TS3 to form the desired amine product. Alternative processes leading to the formation of side products and the influence of different porphyrin ligands with varying electronic properties on the catalytic activity of the cobalt(II) complexes have also been investigated.
最长约 10秒,即可获得该文献文件

科研通智能强力驱动
Strongly Powered by AbleSci AI
更新
PDF的下载单位、IP信息已删除 (2025-6-4)

科研通是完全免费的文献互助平台,具备全网最快的应助速度,最高的求助完成率。 对每一个文献求助,科研通都将尽心尽力,给求助人一个满意的交代。
实时播报
9秒前
14秒前
Qiuyajing完成签到,获得积分10
23秒前
30秒前
星辰大海应助兴奋的嘉懿采纳,获得10
44秒前
祖之微笑发布了新的文献求助10
48秒前
兴奋的嘉懿完成签到,获得积分20
1分钟前
量子星尘发布了新的文献求助10
1分钟前
1分钟前
1分钟前
1分钟前
1分钟前
葱饼完成签到 ,获得积分10
1分钟前
香蕉觅云应助sunshihaoya采纳,获得10
1分钟前
1分钟前
2分钟前
2分钟前
量子星尘发布了新的文献求助10
2分钟前
机灵自中发布了新的文献求助10
2分钟前
机灵自中完成签到,获得积分10
3分钟前
执着的草丛完成签到,获得积分10
3分钟前
3分钟前
Anna完成签到 ,获得积分10
3分钟前
3分钟前
绝世冰淇淋完成签到 ,获得积分10
3分钟前
科研通AI5应助科研通管家采纳,获得50
3分钟前
breeze完成签到,获得积分10
3分钟前
量子星尘发布了新的文献求助10
3分钟前
4分钟前
顺心蜜粉给远航的求助进行了留言
4分钟前
silence发布了新的文献求助10
4分钟前
zhanglq发布了新的文献求助10
4分钟前
silence完成签到,获得积分10
4分钟前
CipherSage应助zhaoaotao采纳,获得10
4分钟前
4分钟前
4分钟前
zhaoaotao发布了新的文献求助10
4分钟前
科研通AI5应助祖之微笑采纳,获得10
4分钟前
zhaoaotao完成签到,获得积分10
4分钟前
4分钟前
高分求助中
A new approach to the extrapolation of accelerated life test data 1000
Picture Books with Same-sex Parented Families: Unintentional Censorship 700
ACSM’s Guidelines for Exercise Testing and Prescription, 12th edition 500
Nucleophilic substitution in azasydnone-modified dinitroanisoles 500
不知道标题是什么 500
Indomethacinのヒトにおける経皮吸収 400
Phylogenetic study of the order Polydesmida (Myriapoda: Diplopoda) 370
热门求助领域 (近24小时)
化学 材料科学 医学 生物 工程类 有机化学 生物化学 物理 内科学 纳米技术 计算机科学 化学工程 复合材料 遗传学 基因 物理化学 催化作用 冶金 细胞生物学 免疫学
热门帖子
关注 科研通微信公众号,转发送积分 3976649
求助须知:如何正确求助?哪些是违规求助? 3520756
关于积分的说明 11204743
捐赠科研通 3257502
什么是DOI,文献DOI怎么找? 1798733
邀请新用户注册赠送积分活动 877897
科研通“疑难数据库(出版商)”最低求助积分说明 806629