2-芳基苯并恶唑是有前途的分子,可在医学和材料领域得到潜在应用。对2-芳基苯并恶唑的直接区域选择性官能化的有效方案有很高的要求。在本文中,我们公开了通用的Cp * Rh(III)能够以高收率实现2-芳基苯并[ d ]恶唑与烯烃的选择性邻烯化的一般方法。该协议具有广泛的功能基团耐受性和高区域选择性。分子间竞争研究和动力学同位素效应实验表明,氧化烯化过程是通过亲电的C–H活化途径发生的。m的分子结构在间位F原子或杂原子取代基存在的情况下,氟取代的烯化产物可在受阻更强的位置证实区域选择性C–H活化/烯化。在单-和双-烯烃化产物的结构中观察到明显的扭转角,这导致烯烃质子的化学位移明显不同。另外,两个克级反应和进一步的转化实验表明,该方法对于合成邻链烯基化的2-芳基苯并恶唑衍生物是实用的。
A catalytic system comprised of Pd(OAc)2 and bidentate ligand dppe enabled first direct arylations with moisture-stable aryl sulfamates as electrophiles, and proved applicable to unprecedented C−H bond functionalizations with easily accessible alkenyl phosphates as well as benzyl phosphates.
Nickel-Catalyzed Coupling of Azoles with Aromatic Nitriles
作者:Mckenna G. Hanson、Noelle M. Olson、Zubaoyi Yi、Grace Wilson、Dipannita Kalyani
DOI:10.1021/acs.orglett.7b01938
日期:2017.8.18
This manuscript describes the Ni-catalyzed coupling of azoles with aromaticnitriles. The use of BPh3 promotes these arylations with electronically diverse azoles and benzonitriles. While the nickel catalyst is necessary for the arylations of phenyl oxazoles, arylation of benzoxazoles with some nitriles affords the arylated products even in the absence of the Ni catalyst albeit in lower yield than
Nickel-catalyzed C−H arylation of benzoxazoles and oxazoles: Benchmarking the influence of electronic, steric and leaving group variations in phenolic electrophiles
作者:Deborah F. Steinberg、Morgan C. Turk、Dipannita Kalyani
DOI:10.1016/j.tet.2017.02.021
日期:2017.4
Electronic, steric and leaving group effects for Ni-catalyzed direct arylations using C-O electrophiles were benchmarked. The scope of arylations with pivalates was general with respect to both the electronics on the electrophile and the azoles. Furthermore, the arylation of azoles with tosylates, mesylates and carbamates with varying electronics was explored, and showed electronic trends similar to those of the pivalate reactions. Finally, the relative rate of arylation of 5-methyl benzoxazole with two electronically-similar electrophiles bearing different leaving groups was established. The results from these studies implicate the following order of relative reactivity: mesylates > pivalates > carbamates. (C) 2017 Elsevier Ltd. All rights reserved.