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
作者:Holger Grugel、Fabian Albrecht、Tobias Minuth、Mike M. K. Boysen
DOI:10.1021/ol3015896
日期:2012.7.20
pseudo-enantiomeric olefinligands were designed from d-glucose and d-galactose. These ligands yield consistently excellent levels of enantioselectivity in Rh(I)-catalyzed 1,4-additions of aryl- and alkenylboronic acids to achiral enones and high diastereoselectivity with chiral substrates. Contrary to established olefinligands, they are obtained enantiomericallypure via short syntheses without racemic
Design of N-sulfinyl homoallylic amines as novel sulfinamide-olefin hybrid ligands for asymmetric catalysis: application in Rh-catalyzed enantioselective 1,4-additions
作者:Shen-Shuang Jin、Hui Wang、Ming-Hua Xu
DOI:10.1039/c1cc12322j
日期:——
Here we show that simple and readily available chiral sulfinamide-olefins can display great catalytic activities and enantioselectivities in rhodium-catalyzed 1,4-addition reactions. This study represent the first example of chiral sulfur-based olefin ligand class for transition metal-catalyzed asymmetric transformation.
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
Convenient in situ generation of a chiral bis-N-heterocyclic carbene palladium catalyst and its application in enantioselective synthesis
作者:Amrita B. Mullick、Matthew S. Jeletic、Andrew R. Powers、Ion Ghiviriga、Khalil A. Abboud、Adam S. Veige
DOI:10.1016/j.poly.2012.07.046
日期:2013.3
To simplify catalytic reactions employing chelating bisNHC-metal complexes, studies were conducted to elucidate conditions for the in situ generation of a chiral chelating bisNHC-palladium catalyst from the corresponding diimidazolium salt. The method provides a convenient entry to catalytic reactions and eliminates catalyst preparation steps. In addition to the in situ prepared catalyst, for comparative purposes, isolable species were synthesized and characterized by NMR spectroscopy, combustion analysis, and single-crystal X-ray diffraction. Employing C-2-symmetric ligands derived from trans-9,10-Dihydro-9,10-EthanoAnthracene-11,12-diyl (DEA) and trans-9,10-Dihydro-9,10-EthanoAnthracene-11,12-diyl-Methanediyl (DEAM), diNHC-Pd complexes were synthesized and tested for activity in enantioselective arylboronic acid addition to cyclic enones. Published by Elsevier Ltd.