Fyfe James W B, Kabia Omaru M, Pearson Colin M, Snaddon Thomas N
Department of Chemistry, Indiana University, 800 E. Kirkwood Ave., Bloomington, Indiana 47405, United States.
Tetrahedron. 2018 Sep 20;74(38):5383-5391. doi: 10.1016/j.tet.2018.04.021. Epub 2018 Apr 10.
Cooperative catalysis enables the direct enantioselective α-allylation of linear prochiral esters using Si-substituted allyl electrophiles. The Si-substituent directs the regioselectivity of enantioselective bond formation and provides products containing synthetically versatile pentafluorophenyl ester and vinylsilane moieties. Critical to the efficacy of this process was the recognition that the ancillary ligand on palladium could be altered to prevent formation of a deleterious ether by-product, whilst retaining enantioselectivity through the Lewis base catalyst. Flexibility such as this is unique to cooperative catalysis events and provides efficient access to an array of enantioenriched products that are orthogonally functionalized and easily modified.
协同催化能够使用硅取代的烯丙基亲电试剂实现线性前手性酯的直接对映选择性α-烯丙基化反应。硅取代基引导对映选择性键形成的区域选择性,并提供含有具有合成多功能性的五氟苯基酯和乙烯基硅烷部分的产物。该过程有效性的关键在于认识到,可以改变钯上的辅助配体以防止有害醚副产物的形成,同时通过路易斯碱催化剂保持对映选择性。这种灵活性是协同催化事件所独有的,并提供了有效获得一系列对映体富集产物的途径,这些产物具有正交官能化且易于修饰的特点。