Asymmetric Hydrogenation of α,β-Unsaturated Carboxylic Acids Catalyzed by Ruthenium(II) Complexes of Spirobifluorene Diphosphine (SFDP) Ligands
作者:Xu Cheng、Jian-Hua Xie、Sheng Li、Qi-Lin Zhou
DOI:10.1002/adsc.200606065
日期:2006.7
The ruthenium diacetate complexes ligated by chiral spirobifluorene diphosphines (SFDP) were very effective catalysts for the asymmetric hydrogenation of tiglic acid derivatives and α-methylcinnamic acid derivatives with high activities and excellent enantioselectivities (up to 98 % ee). The α-aryloxybutenoic acids can also be hydrogenated by these catalysts to provide the corresponding saturated α-aryloxybutanoic
Enzymatic enantioselective ester hydrolysis by carboxylesterase NP
作者:J. W. H. Smeets、A. P. G. Kieboom
DOI:10.1002/recl.19921111104
日期:——
and N-arylalanine esters. The propionate esters yielded propionic acids as (S) enantiomers, whereas the alanine esters yielded the (R) enantiomers. Without a 2-aryl substituent, the enzymatic hydrolysis of the propionates occurred at a lower rate without acceptable enantioselectivity. In addition to 2-substituted propionates, only a few other esters were hydrolyzed with high enantioselectivity by carboxylesterase
Enantioselective Hydrogenation of α-Aryloxy α,β-Unsaturated Acids. Asymmetric Synthesis of α-Aryloxycarboxylic Acids
作者:Peter E. Maligres、Shane W. Krska、Guy R. Humphrey
DOI:10.1021/ol0488035
日期:2004.9.1
[reaction: see text] A facile preparation of chiral alpha-aryloxy carboxylic acids via asymmetrichydrogenation of the corresponding unsaturated acids has been discovered. A number of catalysts have been identified that give high product enantioselectivity, and the scope of the reaction has been examined with respect to substitution on the aromatic ring and olefin.
APPLICATION OF AN IRIDIUM COMPLEX IN ASYMMETRIC CATALYTIC HYDROGENATION OF AN UNSATURATED CARBOXYLIC ACID
申请人:Zhejiang Jiuzhou Pharmaceutical Co., Ltd.
公开号:EP2275398B1
公开(公告)日:2016-05-04
Microbial reduction and resolution of herbicidal 2-alkyl-2-aryloxyacetic acids by Gloeosporium olivarum.
作者:YOSHIKO TSUDA、KENICHI KAWAI、SHOICHI NAKAJIMA
DOI:10.1248/cpb.33.1955
日期:——
When a mold, Gloeosporium olivarum, was fermented with (±)-2-alkyl-2-aryloxyacetic acids (1-8), an enantioselective microbial reduction as well as microbial resolution took place, giving rise to (S)-2-alkyl-2-aryloxyethanols (1a-8a) and (R)-2-alkyl-2-aryloxyacetic acids (1b-8b). The configurations of the chiral 2-alkyl-2-aryloxyethanols and 2-alkyl-2-aryloxyacetic acids were consistent with those of the corresponding products formed by Glomerella cingulata, with the sole exception of 8b. The (R)-(+)-α-methoxy-α-trifluoromethylphenylacetic acid (MTPA) esters of the (S)-2-alkyl-2-aryloxyethanols showed larger lanthanide-induced shifts for the methoxy groups (1a, 4a-8a) or an aromatic proton (2a) in the nuclear magnetic resonance (NMR) spectra than the esters of the corresponding (R)-2-alkyl-2-aryloxyethanols. This result can be applied generally for the determination of the absolute configuration of 2-alkyl-2-aryloxyethanols.