it both ways: A novel class of chiral sulfoxide‐olefin ligands was synthesized from a single chiral source. These ligands were evaluated in rhodium‐catalyzed 1,4‐additions of arylboronic acids to electron‐deficient olefins, and remarkable olefin‐directed reversal of stereoselectivity (up to >99 % ee, R isomer; 98 % ee, S isomer) was observed when the reversal ligand pair L1 (branched olefin) and L2
Application of chiral N-tert-butylsulfinyl vinyl aziridines in Rh(i) catalyzed 1,4-addition of aryl boronic acids to cyclic enones
作者:Qian Chen、Chao Chen、Fang Guo、Wujiong Xia
DOI:10.1039/c3cc42673d
日期:——
Chiral N-tert-butylsulfinyl vinyl aziridine ligands prepared from a readily available (R)-tert-butanesulfinamide have been applied in the rhodium-catalyzedasymmetric1,4-addition of arylboronicacids to cyclic enones, which gives high yields and excellent enantioselectivities.
Synthesis of Silicon-Stereogenic Silanols Involving Iridium-Catalyzed Enantioselective C–H Silylation Leading to a New Ligand Scaffold
作者:Hongpeng Zhang、Dongbing Zhao
DOI:10.1021/acscatal.1c03112
日期:2021.9.3
organosilicon compounds, the enantioselective synthesis of silicon-stereogenic silanols through asymmetric catalysis remains a considerable challenge. Herein, we realized enantioselective construction of silicon-stereogenic diarylsilanols via an Ir-catalyzed C–H silylation of diarylsilanols along with stereospecific substitution or Tamao–Fleming oxidation. This strategy gives rise to a class of chiral diol catalyst
尽管人们越来越关注高度对映体富集的硅-立体异构有机硅化合物的构建,但通过不对称催化对硅-立体异构硅烷醇的对映选择性合成仍然是一个相当大的挑战。在此,我们通过 Ir 催化的二芳基硅烷醇的 C-H 甲硅烷基化以及立体有择取代或 Tamao-Fleming 氧化实现了硅-立体异构二芳基硅烷醇的对映选择性构建。这种策略产生了一类手性二醇催化剂核 (psiols)。psiol 的转化导致配体同时具有 Si 和 P 立体中心,这能够在铑 (I) 催化的芳基硼酸与环己烯酮的共轭 1,4-加成中产生出色的对映选择性。
Developing Chiral Dibenzazepine-Based S(O)-Alkene Hybrid Ligands for Rh(I) Complexation: Catalysts for the Base-Free Hayashi–Miyaura Reaction
作者:Ahmed Chelouan、Siyuan Bao、Sibylle Frieß、Alberto Herrera、Frank W. Heinemann、Ana Escalona、Alexander Grasruck、Romano Dorta
DOI:10.1021/acs.organomet.8b00591
日期:2018.11.12
A stereodivergent synthesis using inexpensive reagents, i.e., dibenzazepine and glucose-derived t-Bu-sulfinate diastereomers (RS)-6 or (SS)-6, affords respective S(O)-alkene hybrid ligands (S)-7 and (R)-7 on gram scales and in excellent optical purity (ee > 99%). Phenyl substitution of the dibenzoazepine backbone generates planar chirality to give epimerization-resistant (pS,RS)-10 diastereoisomer
centers through the sulfur and alkene donor functions. These complexes catalyze the conjugateaddition of arylboronicacids to cyclic Michael acceptors with enantioselectivities of up to 99% ee. DFT calculations show the preponderant influence of planar chirality of the ligand alkene function. The enantioselectivity switch observed between (RS,SC)-11 and (RS,RC)-12 is explained by the inverted cis–trans
苯基二苯并[去质子化B,F ] tropylidene(8)用LDA /吨-BuOK基葡萄糖接着用廉价的非对映体任一淬火吨-Bu-亚磺酸盐([R或( - )小号) - 11次,得到亚砜烯烃混合(S S ,S C)-9 /(S S ,R C)-10和(R S ,R C)-9 /(R S ,S C)-10的非对映体对分别通过色谱/重结晶可将其分离成四个异构体。光学纯的非对映体配体(S S ,S C)-9和(S S ,R C)-10与[RhCl(coe)2 ] 2反应形成双核络合物(R S ,S C)-11和(R S ,R C)-12,其中双齿配体通过硫和烯烃供体的功能配位金属中心。这些络合物以高达99%ee的对映选择性催化芳基硼酸与环状Michael受体的共轭加成。DFT计算显示了配体烯烃官能团的平面手性的主要影响。在(R S ,S C)-11和(R S ,R C)-12之间观察到的对映选择性