Chiral bifunctional phase transfer catalysts introducing bis(diarylhydroxymethyl) substituents at 3,3â²-positions of the chiral binaphthyl core were successfully applied to asymmetric fluorination of cyclic β-keto esters with high enantioselectivities.
Expanding the Boxmi Ligand Family: Synthesis and Application of NON and NSN Ligands
作者:Clemens K. Blasius、Bing-Tao Ren、David Bürgy、Yan-Kai Liu、Bin Li、Ina Michalsky、Hubert Wadepohl、Qing-Hai Deng、Lutz H. Gade
DOI:10.1021/acs.joc.0c00751
日期:2020.5.15
synthetic sequence was transferred to the thio analogue, providing access to the NSN ligand H,Rboxmene. Subsequent complexation experiments with iron and cobaltchloride precursors afforded the four-coordinated chlorido complexes Me,RboxmanMCl2 (R = Ph, iPr; M = Fe, Co) and established the boxman family as trans-chelating, bidentate bis(oxazoline) ligands. Application of the latter in the nickel(II)- and
报道了具有“双(恶唑啉基亚甲基)异苯并呋喃”骨架(boxman)的中性NON配体新家族的两种合成策略。Pd介导的形成异苯并呋喃核的环化反应是八步合成路线中非骨干甲基化目标化合物H,Rboxman的关键反应。相反,引入两个另外的甲基可在主链构建过程中提供立体化学控制,从而获得甲基化的衍生物Me,Rboxman,该衍生物通过五个步骤合成并提高了收率。另外,将合成序列转移至硫代类似物,提供了进入NSN配体H,Rboxmene的途径。随后用铁和氯化钴前体进行的络合实验提供了四配位的氯离子络合物Me,RboxmanMCl2(R = Ph,iPr; M = Fe,Co),并将boxman家族确立为反式螯合双齿双(恶唑啉)配体。后者在镍(II)和锌(II)催化的β-酮酸酯和羟吲哚的α-氟化反应中的应用(产率高达98%,ee高达94%)证明了它们适用于对映选择性催化。
Development of Planar Chiral Iodoarenes Based on [2.2]Paracyclophane and Their Application in Catalytic Enantioselective Fluorination of β-Ketoesters
作者:Yang Wang、Hang Yuan、Hongfei Lu、Wen-Hua Zheng
DOI:10.1021/acs.orglett.8b00711
日期:2018.5.4
The design and synthesis of novel planar chiral iodoarenes based on [2.2]paracyclophane is reported. A process of highly enantioselective oxidative fluorination of a β-ketoester with 3HF–Et3N as a nucleophilic fluoride source mediated by these new hypervalent iodine catalysts has been developed. This represents the first highly enantioselective reaction catalyzed by planar chiral hypervalent iodine
Enantioselective direct fluorination and chlorination of cyclic β-ketoesters mediated by phase-transfer catalysts
作者:Jie Luo、Wenqin Wu、Li-Wen Xu、Yuezhong Meng、Yixin Lu
DOI:10.1016/j.tetlet.2013.03.028
日期:2013.5
A straightforward and practical method for the direct fluorination and chlorination of various beta-ketoesters employing a phase-transfer catalyst is developed. The desired products with fluorine/chlorine-substituted quaternary chiral centers are prepared with good to excellent enantioselectivities. (c) 2013 Elsevier Ltd. All rights reserved.