<i>N</i>,<i>C</i>-Disubstituted Biarylpalladacycles as Precatalysts for ppm Pd-Catalyzed Cross Couplings in Water under Mild Conditions
作者:Ruchita R. Thakore、Balaram S. Takale、Fabrice Gallou、John Reilly、Bruce H. Lipshutz
DOI:10.1021/acscatal.9b04204
日期:2019.12.6
effective palladacycle precatalyst has been identified as that containing an isopropyl group on both an aryl ring and on nitrogen, together with the ligand EvanPhos and triflate as the counterion (P13). This precatalyst is also effective in other C–C bond-forming reactions, such as Heck and Sonogashira couplings. No organic solvents were needed for these processes, while the aqueous reaction medium could be
在寻找增加胶束催化条件下在水中形成催化剂的有效性的方法时,已经研究了保拉他环的母体双芳基胺骨架特征的各种单取代和解离模式以及抗衡离子的作用,目的是减少其用量偶合反应所需的钯的百分数。选择几种含有易于获得的配体的取代的palladacycles进行评估。结果表明(1)不需要通过还原剂处理将Pd(II)盐作为Suzuki-Miyaura(SM)偶联剂的前体进行预活化;(2)相对于先前基于Pd(II)盐和配体的组合所需的Pd负载,反应可以在Pd负载约一半的条件下进行;P13)。该预催化剂在其他C–C键形成反应中也很有效,例如Heck和Sonogashira偶联。这些过程不需要有机溶剂,而水性反应介质可以循环使用几次。一锅四步的步骤涉及Suzuki-Miyaura,还原,烷基化和酰化反应,突显了这种预催化剂在最大程度地降低成本和废物产生的同时最大程度地提高合成收益的潜力。