21150-12-9Relevant academic research and scientific papers
The Synthesis of Chiral α-Aryl α-Hydroxy Carboxylic Acids via RuPHOX-Ru Catalyzed Asymmetric Hydrogenation
Guo, Huan,Li, Jing,Liu, Delong,Zhang, Wanbin
, p. 3665 - 3673 (2017/09/11)
A ruthenocenyl phosphino-oxazoline-ruthenium complex (RuPHOX?Ru) catalyzed asymmetric hydrogenation of α-aryl keto acids has been successfully developed, affording the corresponding chiral α-aryl α-hydroxy carboxylic acids in high yields and with up to 97% ee. The reaction could be performed on a gram scale with a relatively low catalyst loading (up to 5000 S/C) and the resulting products can be transformed to several chiral building blocks, biologically active compounds and chiral drugs. (Figure presented.).
Asymmetric hydrogenation reaction of alpha-ketoacids compound
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Paragraph 0031; 0032; 0033; 0037, (2016/10/10)
The invention relates to the technical field of organic chemistry, especially to an asymmetric hydrogenation reaction of an alpha-ketoacids compound. The asymmetric hydrogenation reaction comprises a scheme shown in the description. In the scheme, R1 is phenyl, substituted phenyl, naphthyl, substituted naphthyl, C1-C6 alkyl, or aralkyl; a substituent group is C1-C6 alkyl, C1-C6 alkoxy, or halogen; and the number of the substituent group is 1-3. In the scheme, M is a chiral spiro-pyridylamino phosphine ligand iridium complex having a structure shown in the description. In the structure, R is hydrogen, 3-methyl, 4-tBu, or 6-methyl.
Direct asymmetric hydrogenation of α-keto acids by using the highly efficient chiral spiro iridium catalysts
Yan, Pu-Cha,Xie, Jian-Hua,Zhang, Xiang-Dong,Chen, Kang,Li, Yuan-Qiang,Zhou, Qi-Lin,Che, Da-Qing
, p. 15987 - 15990 (2015/02/19)
A new efficient and highly enantioselective direct asymmetric hydrogenation of α-keto acids employing the Ir/SpiroPAP catalyst under mild reaction conditions has been developed. This method might be feasible for the preparation of a series of chiral α-hydroxy acids on a large scale.
Relationships between the racemic structures of substituted mandelic acids containing 8- and 10-membered hydrogen bonded dimer rings
Coles,Ellis,Leung,Sarson,Threlfall,Tizzard
, p. 10816 - 10823 (2015/02/19)
The structures of 27 monosubstituted mandelic acids, including several of their polymorphs, plus unsubstituted mandelic acid itself (two polymorphs) are investigated for structural similarity. The results, presented pictorially as a structural relationship plot, show that rather more structures are built up from the carboxyl-chain hydroxyl hydrogen bonded dimer than from the conventional carboxylic acid dimer. The results show how all the structures are related and, based on the two types of dimer, the degree of similarity that they possess. Some structures with Z′ > 1 contain both sorts of dimers and there are many examples of isostructural sets within the structures so far determined. We also present an example where analysing similarity in related families of structures highlights a structure that should be present and which has indeed then proceeded to be synthesised and determined.
Robust enzymatic resolution of 3-fluoromandelic acid with lipase PS supported on celite
Mendiola, Javier,Garcia-Cerrada, Susana,De Frutos, Oscar,De La Puente, Maria Luz
experimental part, p. 1312 - 1316 (2012/10/18)
The resolution of different mandelic acids using the lipase PS Amano SD enzyme is described. By supporting the lyophilized enzyme over Celite, both the activity and the stability of lipase PS in organic media were significantly improved, enabling the robust resolution scale-up of 3-fluoromandelic acid. The methodology was extended to produce a range of optically pure (R)-mandelic acids, avoiding tedious extractions or chromatography.
Mutasynthesis of Glycopeptide Antibiotics: Variations of Vancomycin's AB-Ring Amino Acid 3,5-Dihydroxyphenylglycine
Weist, Stefan,Kittel, Claudia,Bischoff, Daniel,Bister, Bojan,Pfeifer, Volker,Nicholson, Graeme J.,Wohlleben, Wolfgang,Suessmuth, Roderich D.
, p. 5942 - 5943 (2007/10/03)
In the mutasynthetic approach, the ΔdpgA mutant of the vancomycin-type glycopeptide antibiotic producer Amycolatopsis balhimycina, which is deficient in the synthesis of 3,5-dihydroxyphenylglycine (DPg), was supplemented with synthetic DPg analogues to obtain the corresponding modified glycopeptides. Sterically more demanding 3,5-disubstituted methoxy derivatives as well as monosubstituted DPg analogues were accepted as substrates. These facts indicate that steric and electronic requirements suffice in several cases for the oxidative closure of the AB ring, thus leading to the generation of novel antibiotically active glycopeptide derivatives. The results represent a further step in evaluating the potential of mutasynthesis for peptidic secondary metabolites. Copyright
Reaction of carboxylic acids with diethyl phosphorocyanidate; a novel synthesis of homologated α-hydroxycarboxylic acids from carboxylic acids
Mizuno, Masanori,Shioiri, Takayuki
, p. 9209 - 9210 (2007/10/03)
Carboxylic acids react with 2 equivalents of diethyl phosphorocyanidate in the presence of triethylamine to give dicyanophosphates in good yields; these dicyanophosphates can be hydrolyzed easily to give homologated α- hydroxycarboxylic acids.
Reduction of manganate(VI) by mandelic acid and its significance to development of a general mechanism for oxidation of organic compounds by high-valent transition metal oxides
Lee, Donald G.,Chen, Tao
, p. 11231 - 11236 (2007/10/02)
Results obtained from a study of the oxidation of mandelic acid and cyclobutanol by manganate(VI) indicate that reaction mechanisms traditionally applied to oxidations of this type (i.e., hydrogen atom or hydride ion transfers) may not be correct. Instead it appears that the reaction may be initiated by a 2 + 2 addition of the α-C-H bond to a manganese oxo double bond. This interpretation may be useful in the development of a general mechanism for the oxidation of organic compounds by high-valent transition metal oxides including more common oxidants such as permanganate, ruthenium tetroxide, and chromic acid.
The Oxidation of Alcohols by Permanganate. A Comparison with Other High-Valent Transition-Metal Oxidants
Lee, Donald G.,Chen, Tao
, p. 5341 - 5345 (2007/10/02)
The results obtained from a study of the oxidation of mandelic acid and cyclobutanol by permanganate in 1.0 M KOH are best accomodated by a mechanism in which the initial reaction is the addition of a manganese-oxo bond to the α-C-H bond of the alcohol, followed by homolytic cleavage of the resulting Mn-C bond to give free-radical intermediates.A comparison with other high-valent transition-metal oxidants suggests that it is possible to systematically classify the way in which these reagents react with alcohols on the basis of the initial reaction (C-H or O-H addition) and the cleavage mode of the metal-oxygen or metal-carbon bond (homolytic or heterolytic).The approach provides a framework for understanding these reactions that is less chaotic than the current situation where distinctive mechanisms have been proposed for each individual oxidant.
Enantioselectivity of carbonic anhydrase catalyzed hydrolysis of mandelic methyl esters
Chenevert, Robert,Letourneau, Martin
, p. 314 - 316 (2007/10/02)
We report the first enantioselective hydrolysis of esters catalyzed by caebonic anhydrase.We found that mandelic methyl esters are good substrates for carbonic anhydrase.The R enantiomers are better substrates and enantiomeric excess values are moderate (40-51percent).
