Formate as a CO surrogate for cascade processes: Rh-catalyzed cooperative decarbonylation and asymmetric Pauson–Khand-type cyclization reactions
作者:Hang Wai Lee、Albert S. C. Chan、Fuk Yee Kwong
DOI:10.1039/b702718d
日期:——
A rhodium-(S)-xyl-BINAP complex-catalyzed tandem formate decarbonylation and [2 + 2 + 1] carbonylative cyclization is described; this cooperative process utilizes formate as a condensed CO source, and the newly developed cascade protocol can be extended to its enantioselective version, providing up to 94% ee of the cyclopentenone adducts.
作者:Fuk Yee Kwong、Yue Ming Li、Wai Har Lam、Liqin Qiu、Hang Wai Lee、Chi Hung Yeung、Kin Shing Chan、Albert S. C. Chan
DOI:10.1002/chem.200401237
日期:2005.6.20
operationally simple protocol allows both catalyst and reactants to be handled under air without precautions. Various enynes were transformed to the corresponding bicycliccyclopentenones in good yield and enantiomeric excess (up to 95 % ee). A study of the electronic effects of the enyne substrates revealed a correlation between the electronic properties of the substrates and the ee value obtained in
Co/Rhheterobimetallic nanoparticles were prepared from cobalt-rhodium carbonyl clusters [Co2Rh2(CO)12 and Co3Rh(CO)12] and immobilized on charcoal. HR-TEM revealed that the size of the heterobimetallic nanoparticles was ca. 2 nm and ICP-AES analysis showed a 2 : 2 and a 3 : 1 cobalt-rhodium stoichiometry (Co2Rh2 and Co3Rh1) in the heterobimetallic nanoparticles. The Co/Rhheterobimetallic nanoparticles
Rh(I)-Catalyzed Asymmetric Intramolecular Pauson-Khand Reaction in Aqueous Media
作者:Young Keun Chung、Won Hyuck Suh、Mira Choi、Sang Ick Lee
DOI:10.1055/s-2003-41044
日期:——
The first rhodium-BINAP complex-catalyzed enantioselective Pauson-Khand reaction in aqueous media, which is accelerated by surfactant, is reported. The chiral rhodium catalyst is easily prepared in situ from 1 equivalent of [Rh(cod)Cl]2 and 2 equivalents of BINAP under 1 atm of CO and a temperature of 60 °C or 90 °C. Ee’s up to 96% were achieved for the intramolecular Pauson-Khand reaction, but the yields are highly dependent upon the substrate itself.
Electronic and Steric Effects of Atropisomeric Ligands SYNPHOS® and DIFLUORPHOS®vs. BINAPs in Rh(I)-Catalyzed Asymmetric Pauson–Khand Reaction
作者:Dong Eun Kim、Choong Choi、In Su Kim、Séverine Jeulin、Virginie Ratovelomanana-Vidal、Jean-Pierre Genêt、Nakcheol Jeong
DOI:10.1002/adsc.200600623
日期:2007.8.6
electronic and steric effects of chiral biaryl diphosphine ligands on the Rh(I)-catalyzed asymmetricPauson–Khand type reaction were examined. We demonstrated that enantioselectivity and reaction yield were influenced by the electronic density on phosphorus, the dihedral angle of ligands and the electronic density of the alkyne substrate. Ligands bearing a narrower dihedral angle than Binap, such as Synphos