Design and Synthesis of Polymeric Chiral Bicyclo[3.3.0] Diene as Reusable Ligand for Rhodium-Catalyzed Asymmetric 1,4-Addition
作者:Hongyu Yang、Minghua Xu
DOI:10.1002/cjoc.201201079
日期:2013.1
A series of A‐B type sterically regular bicyclio[3.3.0] diene‐based polymers were designed and synthesized as immobilized chiraldieneligands for asymmetric catalysis. With polymericdiene 6b, good to excellent enantioselectivities can be achieved in Rh‐catalyzed asymmetric 1,4‐addition of arylboronic acids to α,β‐unsaturated ketones.
Fine‐Tuning the Bicyclo[3.3.1]nona‐2,6‐diene Ligands: Second Generation 4,8‐Substituted Dienes for Rh‐Catalyzed Asymmetric 1,4‐Addition Reactions
作者:Vidmantas Bieliūnas、Sigitas Stončius
DOI:10.1002/cctc.202100638
日期:2021.9.7
C2-symmetric 4,8-endo,endo-bis(alkoxy) bicyclo[3.3.1]nona-2,6-diene ligands possessing additional 4,8-exo,exo substituents is reported. The 4,8-exo,exo groups provide a further element for fine-tuning of the ligand structure by enforcing conformational rigidity of the 4,8-endo,endo side chains. Such tetrasubstituted bicyclo[3.3.1]nona-2,6-dienes were employed as steering ligands in the rhodium-catalyzed arylation
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
An N-Linked Bidentate Phosphoramidite Ligand (N-Me-BIPAM) for Rhodium-Catalyzed Asymmetric 1,4-Addition of Arylboronic Acids to α,β-Unsaturated Ketones
on Shibasaki’s N-linked BINOL was synthesized. This ligand appears to be highly effective for rhodium-catalyzed asymmetric conjugatedaddition of arylboronicacids to α,β-unsaturated enones. The reaction of ortho-substituted arylboronicacid with acyclic and cyclic enones provides the corresponding products in good yields and enantioselectivities.
Aryloxymethyltrifluoroborates for Rhodium-Catalyzed Asymmetric Conjugate Arylation. <i>o</i>-Methoxyarylation through 1,4-Rhodium Shift
作者:Jialin Ming、Tamio Hayashi
DOI:10.1021/acs.orglett.6b03347
日期:2016.12.16
enantioselectivity in high yields. The reaction is assumed to proceed through 1,4-Rh shift from aryloxymethyl-Rh intermediate to 2-methoxyaryl-Rh. The high availability of phenol derivatives makes this asymmetric conjugate arylation synthetically useful.