Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China.
Org Lett. 2021 Apr 16;23(8):3157-3161. doi: 10.1021/acs.orglett.1c00801. Epub 2021 Mar 29.
Asymmetric functionalization of inert C(sp)-H bonds is a straightforward approach to realize versatile bond-forming events, allowing the precise assembly of molecular complexity with minimal functional manipulations. Here, we describe an asymmetric photocatalytic C(sp)-H bond addition to α-substituted acrylates by using tetrabutylammonium decatungstate (TBADT) as a hydrogen atom transfer (HAT) photocatalyst and chiral phosphoric acid as a chiral proton-transfer shuttle. This protocol is supposed to occur via a radical/ionic relay process, including a TBADT-mediated HAT to cleave the inert C(sp)-H bond, a 1,4-radical addition, a back hydrogen abstraction, and an enantioselective protonation. A variety of inert C-H bond patterns and α-substituted acrylates are well tolerated to enable the rapid synthesis of enantioenriched α-stereogenic esters from simple raw materials.
不对称功能化惰性 C(sp)-H 键是实现多功能键形成事件的直接方法，允许通过最小的功能操作精确组装分子复杂性。在这里，我们描述了通过使用四丁基铵十钨酸盐 (TBADT) 作为氢原子转移 (HAT) 光催化剂和手性磷酸作为手性质子转移穿梭物，通过不对称光催化 C(sp)-H 键加成到 α-取代丙烯酸盐。该方案被认为是通过自由基/离子接力过程发生的，包括 TBADT 介导的 HAT 以断裂惰性 C(sp)-H 键、1,4-自由基加成、回氢提取和对映选择性质子化。各种惰性 C-H 键模式和 α-取代丙烯酸盐都可以很好地耐受，从而能够从简单的原料快速合成对映体富集的 α-手性酯。
