Mechanistic Insight into Rh-Catalyzed C(sp<sup>2</sup>)–O Bond Cleavage Applied to Cross-Coupling Reaction of Benzofurans with Aryl Grignard Reagents
作者:Takanori Iwasaki、Wataru Ishiga、Shrinwantu Pal、Kyoko Nozaki、Nobuaki Kambe
DOI:10.1021/acscatal.2c01974
日期:2022.7.1
facilitated not only C–O bond cleavage but also the insertion of the C═C bond into the Rh–Ph bond. These strategies and mechanistic insights were successfully applied to develop a strategy for the Rh-catalyzed cross-coupling reaction of fused vinylic ethers, benzofurans, and aryl Grignard reagents, wherein the bond cleavage occurred selectively at the vinylic C(sp2)–O bond, even in the presence of
本文报道了 Rh 催化的乙烯基醚与芳基格氏试剂通过 C(sp 2 )-O 键断裂发生交叉偶联反应的机理研究。为了获得机理见解,反应在流动反应器中进行,动力学研究表明,对于乙烯基醚和芳基格氏试剂,反应分别服从一级和零级动力学。Rh预催化剂中的烯烃配体对催化性能有显着影响,[RhCl(CH 2 = CH 2 ) 2 ] 2的催化活性约为. 比 [RhCl(cod)] 2高 110 倍. 此外,动力学研究表明,二齿辅助配体 COD 形成了一种休眠物质以减缓催化周转。计算研究表明,由 Rh 预催化剂与两分子芳基格氏试剂反应生成的二芳基铑与乙烯基醚之间的反应是通过 Mg 阳离子辅助插入/抗-β-氧消除而不是氧化加成/还原消除和乙烯基碳上的亲核取代(S N2 伏)。在过渡态中,Mg 抗衡阳离子与基底中的醚氧原子配位,不仅促进了 C-O 键的断裂,而且促进了 C=C 键插入 Rh-Ph 键。这些策略和机