Axially Chiral C2-Symmetric N-Heterocyclic Carbene (NHC) Palladium Complex-Catalyzed Asymmetric Fluorination and Amination of Oxindoles
作者:Rui Zhang、De Wang、Qin Xu、Jiajun Jiang、Min Shi
DOI:10.1002/cjoc.201200289
日期:2012.6
Chiral C2‐symmetric N‐heterocyclic carbene (NHC) palladium diaquo complex 5b prepared from (S)‐BINAM was found to be a fairly effective catalyst for the enantioselective asymmetric fluorination of oxindoles to give the corresponding products in moderate enantioselectivities along with good to excellent yields.
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。
Iron(iii)–salan complexes catalysed highly enantioselective fluorination and hydroxylation of β-keto esters and N-Boc oxindoles
作者:Xin Gu、Yan Zhang、Zhen-Jiang Xu、Chi-Ming Che
DOI:10.1039/c4cc01631a
日期:——
Chiral iron(III)âsalan complexes catalysed highly enantioselective α-fluorination and α-hydroxylation of β-keto esters and N-Boc oxindoles to give the corresponding products in high yields and good-to-excellent ee values under mild reaction conditions.
Structurally modified N-fluorobenzenesulfonimides (NFSIs) have been used to study the enantioselective fluorination of oxindoles in the presence of a bis-cinchona alkaloid, (DHQD)(2)PHAL, as the catalyst. We observe that the NFSI analogues bearing two tert-butyl groups at the para-position of the symmetric phenyl rings led to an enhanced enantioselectivity in most cases (up to 96% ee) compared with the unmodified NESIs (less than 69% ee). (C) 2013 Elsevier Ltd. All rights reserved.