Electronic Effects in Asymmetric Catalysis: Structural Studies of Precatalysts and Intermediates in Rh-Catalyzed Hydrogenation of Dimethyl Itaconate and Acetamidocinnamic Acid Derivatives Using <i>C</i><sub>2</sub>-Symmetric Diarylphosphinite Ligands
作者:T. V. RajanBabu、Branko Radetich、Kamfia K. You、Timothy A. Ayers、Albert L. Casalnuovo、Joseph C. Calabrese
DOI:10.1021/jo9901182
日期:1999.5.1
largely unaffected by electronic effects, which suggests that other explanations have to be sought for the electronic amplification of enantioselectivity. One possibility is a change in the diastereomeric equilibrium between the initially formed [substrate]Rh(+)[phosphinite] complexes as a function of electronic effect of the ligand. In the Rh-catalyzed hydrogenation of dimethyl itaconate, we have examined
Strategies for protection and deprotection of OH-groups in the presence of phosphines have been explored. Rate acceleration in the Baylis-Hillman reaction was observed when a hydroxyl phosphine was used as the catalyst. Rhodium complexes with chiral bisphospholanes are highly enantioselective catalysts for the asymmetrichydrogenation of various kinds of functionalized olefins such as dehydroamino
A Novel Chiral Ferrocenyl Phosphine Ligand from Sugar: Applications in Rh-Catalyzed Asymmetric Hydrogenation Reactions
作者:Duan Liu、Wenge Li、Xumu Zhang
DOI:10.1021/ol0269998
日期:2002.12.1
[structure: see text] A new chiral ferrocenyl diphosphine ligand 3 was synthesized from readily available D-mannitol. Rh-complex with this ligand showed high enantioselectivity and reactivity in the asymmetric hydrogenation of dehydroamino acid derivatives and itaconic acid derivatives. Up to over 99% ee and 10 000 TON were achieved with this catalytic system.
Supramolecular chiral dendritic monophosphites assembled by hydrogen bonding and their use in the Rh-catalyzed asymmetric hydrogenation
作者:Yong Li、Yan-Mei He、Zhi-Wei Li、Feng Zhang、Qing-Hua Fan
DOI:10.1039/b823047a
日期:——
A new type of supramolecular chiral dendritic monophosphite ligands has been prepared via a hydrogen-bonding assembly. The Rh complexes of these supramolecular ligands have been successfully applied in the asymmetric hydrogenation of enamides and dehydroamino acid derivatives with good enantioselectivities, which are comparable to those obtained from the free monophosphite ligands. The supramolecular catalyst could be easily recycled viasolvent precipitation.
A chiral hydroxyl bisphospholane, 1,2-bis[(2S,3S,4S,5S)-3,4-dihydroxyl-2,5-dimethylphospholanyl]benzene (4), was synthesized from readily available d-mannitol. Its Rh(I) complex catalyzes asymmetric hydrogenation of dehydroaminoacids and their ester derivatives with excellent enantioselectivities (98 to >99% ee).