通过芳环上的取代基与金属催化剂的配位,金属催化的氢的亲核芳族取代 (S N ArH) 在反应性、底物类型和反应选择性方面,补充了过渡金属催化的 C-H 官能化通过 C-H 金属化进行,但仍然是一个难以捉摸的目标。本文描述了一种前所未有的钴催化偶氮苯对位选择性胺化的发展,其本质上是由 Hammett 分析揭示的金属促进的 S N ArH 过程,从而说明了芳烃环上的取代基与金属催化剂可能导致芳烃环向 S N亲电活化氩气。这种钴催化的方案允许使用多种脂肪胺和苯胺作为胺化试剂,耐受偶氮苯的电子多样化取代基,并以良好的产率提供相应的产品,并对对胺化具有区域特异性选择性。
The effects of cyclic terminal groups in 4-aminoazobenzene and related azo dyes. Part 3. Electronic absorption spectra of some monoazo dyes derived from N-phenylmorpholine, N-(phenyl)thiomorpholine, N-(phenyl)thiomorpholine 1,1-dioxide, and N-acetyl-N′-phenylpiperazine
作者:Geoffrey Hallas、Richard Marsden、John D. Hepworth、Donald Mason
DOI:10.1039/p29860000123
日期:——
Monoazo dyes containing a terminal morpholino group absorb hypsochromically in comparision with their piperidino counterparts as a result of electron withdrawal by the oxygen atom. Similar shifts are observed with related dyes possessing other γ-heteroatoms in the donor group. In acid solution, protonation takes place at the β-azo nitrogen atom (azonium tautomer) and at the terminal nitrogen atom (ammonium