Practical asymmetric hydrogenation of β-keto esters at atmospheric pressure using chiral Ru (II) catalysts
作者:J.P. Genêt、V. Ratovelomanana-Vidal、M.C. Caño de Andrade、X. Pfister、P. Guerreiro、J.Y. Lenoir
DOI:10.1016/0040-4039(95)00873-b
日期:1995.7
conditions of asymmetrichydrogenation of β-keto esters with chiralRu(II) catalysts are described. It is now possible to carry out the reaction at atmospheric pressure. Under these conditions, β-keto esters are hydrogenated to β-hydroxy esters with excellent enantiomeric excesses (up to 99%) using chiral ruthenium (II) catalysts easily prepared in situ by treatment of commercially available (COD)Ru(2-methylallyl)2
new class of 2-methylallyl ruthenium chiral diphosphines 1 are efficient in asymmetric hydrogenation of α,β unsaturated acids and allylic alcohols. The related chiral halogen-containing ruthenium catalysts 2 are prepared from 1 or in situ from (COD)Ru(η)3-(CH2)2CHCH3)2 by ligand exchange with the chelatingdiphosphine followed by protonation (HX) in acetone. This procedure allows rapid screening of chiral
Optically active compound and process for producing the same
申请人:Takasago International Corporation
公开号:US05998668A1
公开(公告)日:1999-12-07
An optically active (2S,3R)-2-(3'-hydroxyacyl)aminoalkane-1,3-diol and a process for producing the same are disclosed. The compound is represented by the following general formula (1): ##STR1## wherein R.sup.1 represents a linear or branched, saturated aliphatic hydrocarbon group having 9 to 19 carbon atoms; R.sup.2 represents a linear or branched, saturated aliphatic hydrocarbon group having 1 to 19 carbon atoms; and symbol * means that the carbon atom is an asymmetric carbon atom of the S or R configuration. The optically active compound is a ceramide in which the fatty acid moiety has an optically active hydroxyl group in the 3-position.
The Preparation of Optically Pure 3-Hydeoxybutanoic Acid and Its Homologues as the Dibenzylammonium Salt
作者:Tadashi Kikukawa、Yoshitomi Iizuka、Takashi Sugimura、Tadao Harada、Akira Tai
DOI:10.1246/cl.1987.1267
日期:1987.7.5
Optically pure (R)- and (S)-3-hydroxybutanoic acid and itshomologues are prepared by the method consisting of the enantioface differentiating hydrogenation of methyl 3-oxoalkanoate to methyl 3-hydroxyalkanoate(80–90% e.e.) over asymmetrically modified nickel catalyst and the preferential crystallization of optically pure 3-hydroxyalkanoic acids from the hydrogenation products as the dibenzylammonium
An Improved Asymmetric Reformatsky Reaction Mediated by (−)-<i>N</i>,<i>N</i>-Dimethylaminoisoborneol
作者:Ralf J. Kloetzing、Tobias Thaler、Paul Knochel
DOI:10.1021/ol0531381
日期:2006.3.1
(-)-N,N-Dimethylaminoisoborneol ((-)-DAIB) was found to be an excellent ligand for the enantioselective addition of Reformatsky reagents to aromatic and aliphatic aldehydes. Enantioselectivities up to 93% ee were obtained with sulfur-containing aldehydes.