Bis(dialkylphosphino)ferrocene-Ligated Nickel(II) Precatalysts for Suzuki–Miyaura Reactions of Aryl Carbonates
作者:Emily L. Barth、Ryan M. Davis、Megan Mohadjer Beromi、Andrew G. Walden、David Balcells、Gary W. Brudvig、Amira H. Dardir、Nilay Hazari、Hannah M. C. Lant、Brandon Q. Mercado、Ian L. Peczak
DOI:10.1021/acs.organomet.9b00543
日期:2019.9.9
(dcypf)Ni(2-ethylphenyl)(Br), which contains a bidentate phosphine that binds in a trans geometry, is an effective precatalyst for these reactions for two reasons: (i) it rapidly forms the Ni(0) active species and (ii) it minimizes comproportionation reactions between the Ni(0) active species and both the unactivated Ni(II) precatalyst and on-cycle Ni(II) complexes to form catalytically inactive Ni(I)
碳酸芳基酯是合成有机化学中常见的保护基,在交叉偶联反应中是潜在有价值的亲电子试剂。在这里,对不同的预催化剂进行了全面的评估后,我们证明了(dcypf)Ni(2-乙基苯基)(Br)(dcypf = 1,1-双(二环己基膦基)二茂铁)是一种有效的Suzuki–Miyaura反应的预催化剂,使用各种碳酸芳基酯作为底物。机理研究表明,(dcypf)Ni(2-乙基苯基)(Br)包含以反式几何构型结合的双齿膦,由于以下两个原因,它们是有效的预催化剂:(i)它迅速形成Ni(0)活性物质,并且(ii)最大限度地减少了Ni(0)活性物质与未活化的Ni(II)预催化剂和循环中Ni(II)络合物之间的配位反应,从而催化形成惰性的Ni(I)物种。相反,现有技术的预催化剂(dppf)Ni(邻甲苯基)(Cl)(dppf = 1,1-双(二苯基膦基)二茂铁),其中含有以顺式几何形状结合的二齿膦,在活化过程中形成Ni(I