ETH Zürich, Vladimir-Prelog-Weg 3, HCI, 8093 Zürich, Switzerland.
J Am Chem Soc. 2021 Mar 10;143(9):3323-3329. doi: 10.1021/jacs.1c00609. Epub 2021 Mar 1.
Enantioselective bond formation between sterically hindered fragments to furnish acyclic products with vicinal quaternary centers is a formidable challenge. We report a solution that involves cocatalysis between a chiral Ir-(phosphoramidite,olefin) complex and La(OTf). This robust catalytic system effects highly enantioconvergent and regioselective alkylation of racemic tertiary α-allenyl alcohols with tetrasubstituted silyl ketene acetals. The transformation displays broad functional group tolerance for both reaction components and allows efficient generation of β-allenyl ester products in good yield and with excellent enantioselectivity. Furthermore, both the allene and ester functionalities were leveraged to upgrade the structural complexity of the products via a series of stereoselective metal-catalyzed functionalization reactions.
手性受阻片段之间的对映选择性键形成，以提供具有毗邻季碳原子的非环产物，是一项艰巨的挑战。我们报告了一种涉及手性 Ir-(膦酰胺，烯烃)配合物和 La(OTf)之间共催化的解决方案。这种强大的催化体系可以实现外消旋叔 α-烯丙基醇与四取代硅基酮缩醛的高对映选择性和区域选择性烷基化。该转化对两个反应组分均具有广泛的官能团耐受性，并允许以良好的收率和优异的对映选择性有效地生成β-烯丙基酯产物。此外，通过一系列立体选择性金属催化官能化反应，利用烯丙基和酯官能团来提高产物的结构复杂性。
