20698-91-3Relevant articles and documents
Effects of organic solvents and ionic liquids on the aminolysis of (RS)-methyl mandelate catalyzed by lipases
Pilissao, Cristiane,Nascimento, Maria Da Graca
, p. 428 - 433 (2006)
The enzymatic resolution of (RS)-methyl mandelate with n-butylamine using lipases in organic solvents (n-hexane, tert-butanol, and chloroform) and ionic liquids [BMIm][BF4] and [BMIm][PF6] is reported. The amide configuration is dependent on the organic solvent. When using mixtures of chloroform or tert-butanol/ionic liquids (10:1 v/v) with CAL-B as the catalyst, the amides were obtained in high enantiomeric excess (eep >99% and E >200).
Supramolecular crystalline construction based on a mandelic acid source. host design, inclusion formation and X-ray crystal structures of a methanol inclusion complex and free host structures in racemic and optically resolved forms
Weber, Edwin,Hager, Orm,Foces-Foces, Concepcion,Llamas-Saiz, Antonio L.
, p. 50 - 60 (1996)
A new host compound in optically resolved and racemic forms for selective crystalline inclusion formation derived from natural mandelic acid was synthesized. Inclusion properties of the two optical species are discussed, involving comparison with a lactic acid-based host analogue. Inclusion compounds with amines, ketones and heterocyclics and specifically with small unbranched alcohols were isolated. The crystal and molecular structures of the optically resolved and racemic forms of the free host at room temperature and the methanol inclusion complex of the resolved host at 255 K were determined by x-ray analysis. Two different binding schemes characterize the packing of these structures, in which one hydroxyl group is responsible for the formation of dimers and chains while in the free host the other hydroxyl group is involved in OH-phenyl interactions. A survey of the OH...phenyl interactions based on the Cambridge Structural Data Base (October 1994 version) reveals that π-electron bonding occurs in a wide range of crystal structures. The approximation of the hydrogen appears to take place in an asymmetric way. Several calculations for the ab initio prediction of the crystal structures were performed.
New data to the origin of rate enhancement on the Pt-cinchona catalyzed enantioselective hydrogenation of activated ketones using continuous-flow fixed-bed reactor system
Szoellosi, Gyoergy,Cserenyi, Szabolcs,Fueloep, Ferenc,Bartok, Mihaly
, p. 245 - 253 (2008)
A study on the origin of rate enhancement (RE) in the enantioselective heterogeneous catalytic hydrogenation of methyl benzoylformate (MBF), ketopantolactone (KPL) and pyruvic aldehyde dimethyl acetal (PA) under the Orito reaction conditions over Pt catalyst modified with parent cinchona alkaloids, as compared to the unmodified catalyst is presented. The hydrogenations were carried out in continuous-flow fixed-bed reactor system over 20-100 mg Pt/Al2O3 catalyst in 1 mL min-1 flow of toluene/acetic acid 9/1 solvent mixture under 40-80 bar H2 pressure, at 283 or 293 K using 0.044-2 mM modifier concentration and 45 mM substrate concentration. Our results obtained using racemic hydrogenations followed by three changes of the chiral modifier (on the same catalyst) supported the so-called "ligand acceleration" phenomenon in the enantioselective hydrogenation of activated ketones such as MBF, KPL and PA. In our opinion, RE produced by the first modifier added after racemic hydrogenation can also be explained by the purifying effect of the cinchona. REs observed following further exchanges of modifiers are indicative of the intrinsic character of the phenomenon. This research suggested that the origin of enantiodifferentiation and rate enhancement is the same, namely, both may be traced back-probably in different ways-to the role of the intermediate complexes of the hydrogenation, to its formation and transformation, which in turn depends on numerous factors.
REDUCTIONS WITH NADH MODELS II: ASYMMETRIC INDUCTION WITH SUGAR SUBSTITUTED HANTZSCH ESTERS OR WITH CHIRAL LEWIS ACIDS
Zehani, Sadek,Lin, Jian,Gelbard, Georges
, p. 733 - 740 (1989)
Hantzsch esters 3 and 4 have been used as NADH models instead of the well documented nicotinamides 1 for the sake of greater flexibility in the preparation and chemical modifications.Compounds 3 and 4, bearing monosaccharide-derived substituents in the 4- or in both the 3- and 5- positions were examined in the asymmetric reduction of several prochiral ketones: namely methyl phenylglyoxylate, trifluoroacetophenone and 2-acetyl pyridine.The e.e. 's obtained are discussed in terms of the structure of the sugar residue and its position on the dihydropyridine ring.The effects of Mg2+ catalysis is discussed and the possibility of using others Lewis acids - especially chiral ones - is examined.
Enantiocomplementary preparation of (S)- and (R)-mandelic acid derivatives via α-hydroxylation of 2-arylacetic acid derivatives and reduction of α-ketoester using microbial whole cells
Chen, Yongzheng,Xu, Jinggang,Xu, Xiaoying,Xia, Yu,Lin, Hui,Xia, Shiwen,Wang, Lixin
, p. 2537 - 2540 (2007)
Forty one microorganisms belonging to different taxonomical groups were used to carry out the enantioselective reduction of methyl benzoylformate to afford the corresponding (R)-methyl mandelate, with moderate to high ee. In contrast, the monooxygenase en
A new type of NADH model compound: Synthesis and reactions
Li, Xianfeng,Tanner, Dennis D.
, p. 3275 - 3278 (1996)
Four diastereomeric NADH model compounds were synthesized by the reaction of a pinyl substituted Hantzch ester with dimethylaluminum amide. The reduction of methyl benzoylformate with these models gave both enantiomers of methyl mandelate
Effect of the neighbouring oxygenated substituent on asymmetric reduction with Hantzsch-type 1,4-dihydropyridines having a chiral sulfinyl group
Miyashita, Kazuyuki,Nishimoto, Masahiro,Murafuji, Hidenobu,Murakami, Asuka,Obika, Satoshi,In, Yasuko,Ishida, Toshimasa,Imanishi, Takeshi
, p. 2535 - 2536 (1996)
Introduction of the oxygen substituent at C-6 of the Hantzsch-type compound having a sulfinyl group at C-5 affects the reduction of ketones with respect to both reactivity and stereoselectivity.
Novel silica gel supported chiral biaryl-diphosphine ligands for enantioselective hydrogenation
Steiner, Ivo,Aufdenblatten, Rhony,Togni, Antonio,Blaser, Hans-Ulrich,Pugin, Benoit
, p. 2307 - 2311 (2004)
The synthesis of functionalized Biphemp and MeO-Biphep biaryl diphosphine ligands and their covalent attachment to silica gel are described. The catalytic performance of the immobilized ligands was tested in the asymmetric hydrogenation of methyl acetamid
Asymmetric reduction of α-keto esters with Thermus thermophilus NADH-dependent carbonyl reductase using glucose dehydrogenase and alcohol dehydrogenase for cofactor regeneration
Pennacchio, Angela,Giordano, Assunta,Rossi, Mose,Raia, Carlo A.
, p. 4361 - 4366 (2011)
The enantioselective synthesis of methyl (R)-mandelate and methyl (R)-o-chloromandelate was investigated using an NADH-dependent carbonyl reductase from Thermus thermophilus (TtADH) and, separately, archaeal glucose dehydrogenase and Bacillus stearothermo
The Enzyme/Coenzyme/Metal/Substrate Quaternary Complex Generated in the Transition State of the Reduction of Benzoylformate with NAD(P)H Models
Mikata, Yuji,Mizukami, Kiyoko,Ikehara, Kenji,Ohno, Atsuyoshi
, p. 6491 - 6494 (1995)
Enantioselectivities in the reduction of methyl benzoylformate with NAD(P)H model compounds, N-α-methylbenzyl-1-propyl-1,4-dihydronicotinamide (PNPH) and N-benzyl-1-propyl-1,4-dihydronicotinamide (PNBH), in the presence of N-protected amino acids have bee
