Regiodivergent Cross-Dehydrogenative Coupling of Pyridines and Benzoxazoles: Discovery of Organic Halides as Regio-Switching Oxidants
作者:Shuya Yamada、Kei Murakami、Kenichiro Itami
DOI:10.1021/acs.orglett.6b00932
日期:2016.5.20
regio-divergent heterocyclic CDCs is considered crucial. In this Letter, the unprecedented use of organic halides as an oxidant to achieve the CDC reaction of pyridines and benzoxazoles with palladium catalyst is described. Moreover, the regioselectivity of the pyridine functionalization site can be controlled by the choice of organic halides.
An efficient Palladium/Copper bimetallic co-catalyzed direct 2-arylation of benzoxazoles with aryl chlorides is presented. The Pd(OAc)2/CuI/NiXantphos-based catalyst enables the installation of various aryl and heteroaryl groups in good to excellent yields (75–99%). Preliminary mechanism investigation indicates that Pd/Nixantphos complex activates C-Cl bond of aryl chlorides via oxidative addition
提出了一种有效的钯/铜双金属共催化的苯并恶唑与芳基氯化物的2-芳基化反应。基于Pd(OAc)2 / CuI / NiXantphos的催化剂能够以优异的产率(75-99%)安装各种芳基和杂芳基。初步的机理研究表明,Pd / Nixantphos配合物通过氧化加成激活芳基氯的C-Cl键,而Cu / Nixantphos配合物与氮原子螯合以降低苯并恶唑中2-H的pK a。