- Modular 1,1′-Ferrocenediyl-cored P-Stereogenic Diphosphines: ′′JDayPhos′′ Series and its Use in Rhodium(I)-Catalyzed Hydrogenation
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A novel ferrocene-based P-stereogenic diphospine ligand series dubbed JDayPhos was developed, which rhodium(I) complexes of some of its members exhibited excellent enantioselectivity (up to >99% ee) and high activity in asymmetric hydrogenation of β-unsubstituted or -substituted itaconates and α-methylene-γ-oxo-carboxylates. (Figure presented.).
- Poklukar, Ga?per,Stephan, Michel,Mohar, Barbara
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p. 2566 - 2570
(2018/05/16)
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- Identification, synthesis and characterization of impurities of (S)-Mitiglinide calcium dihydrate
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(S)-Mitiglinide Calcium dihydrate (1), an important potent hypoglycemic agent. During laboratory optimization and later in bulk synthesis the formation of various impurities was observed. The method of preparation of most of these impurities is not availa
- Umasankara Sastry,Nageswara Rao,Appi Reddy,Gandhi
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p. 2417 - 2421
(2014/06/09)
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- A facile chemoenzymatic approach to chiral non-racemic β-alkyl-γ-amino acids and 2-alkylsuccinic acids. A concise synthesis of (S)-(+)-Pregabalin
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Both enantiomerically pure antipodes of GABA analogues were prepared as hydrochloride salts, by enzymatic kinetic resolution of their precursors ethyl 2-(nitromethyl)alkanoates. These latter compounds can be easily transformed into enantiomerically pure 2-alkylsuccinic acids by a Nef reaction followed by oxidation. Interestingly, this reaction was particularly easy for the neopentyl derivative (S)-(+)-7d, which underwent conversion into its corresponding succinic acid derivative (S)-(-)-8d in buffered solution. The absolute configurations of the main compounds of interest involved are given, together with their CD spectra.
- Felluga, Fulvia,Pitacco, Giuliana,Valentin, Ennio,Venneri, Cesare Daniele
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p. 945 - 955
(2008/09/21)
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- Synthesis and application of phosphinoferrocenylaminophosphine ligands for asymmetric catalysis
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(Chemical Equation Presented) A new class of bidentate ligands utilizing a phosphine-aminophosphine structure has been prepared on a ferrocenylethyl backbone in a straightforward and scalable fashion from acetylferrocene. The unique property of the α-ferrocenyl carbonium ion that allows the replacement of a variety of "leaving groups" with retention of configuration greatly facilitates the synthesis, and a number of ligands have been prepared by varying the nitrogen and phosphorus substituents on the aminophosphine. These readily prepared phosphinoferrocenylaminophosphines, known as BoPhoz ligands, show surprising hydrolytic and air stability, with no degradation after 3 years open to the air. The rhodium complexes of these ligands show exceedingly high enantioselectivities (generally > 95% ee) and activities often in excess of 50 000 catalyst turnovers per hour for the asymmetric hydrogenation of a wide variety of dehydro-α-amino acid and itaconic acid derivatives. They also show high activity and good to excellent enantioselectivity for the hydrogenation of a number of α-ketoesters.
- Boaz, Neil W.,Mackenzie, Elaine B.,Debenham, Sheryl D.,Large, Shannon E.,Ponasik Jr., James A.
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p. 1872 - 1880
(2007/10/03)
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- Diastereoselective conjugate addition of Grignard reagents to a homochiral fumaramide derived from Oppolzer's sultam
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Conjugate addition of Grignard reagents to N,N′-fumaroylbis[(2R)- bornane-10,2-sultam] 1 occurred with moderate to high levels of diastereoselectivity. Diastereomeric excesses were estimated by analysis of the 1H NMR spectra of the succinamide mixtures and enantiomeric excesses from 19F NMR spectra of the bis Mosher esters of the diols produced by reductive cleavage of the succinamides. Saponification of the succinamides gave the corresponding (R)-succinic acids with ees up to 92% showing that addition of the Grignard reagents takes place selectively on the re-face of 1.
- Reid, Gary P.,Brear, Kieron W.,Robins, David J.
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p. 793 - 801
(2007/10/03)
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- Preparation of (R)-(-)- and (S)-(+)-3-hydroxymethyl-1-tetralone tosylates, key intermediates in the synthesis of new CNS drugs, via resolution of precursors
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The preparation of (R)-(-)- and (S)-(+)-3-hydroxymethyl-1-tetralone tosylates, key intermediates in the synthesis of new CNS drugs in the aminobutyrophenone family, has been developed via classical resolutions or lipase-catalyzed kinetic resolution of one of their precursors.
- Caro, Yolanda,Masaguer, Christian F.,Ravina, Enrique
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p. 381 - 387
(2007/10/03)
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- Phosphinoferrocenylaminophosphines as novel and practical ligands for asymmetric catalysis
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(Matrix Presented) A new series of ligands with a novel phosphine-aminophosphine ligation design as depicted in structure 1 has been prepared on a ferrocenylethyl backbone. These BoPhoz ligands of structure 2 have afforded exceedingly high activity and enantioselectivity in the rhodium-catalyzed asymmetric hydrogenation of dehydro-α-amino acid derivatives, itaconic acids, and α-ketoesters. These air-stable ligands are readily prepared from cost-effective and non-pyrophoric intermediates.
- Boaz, Neil W.,Debenham, Sheryl D.,Mackenzie, Elaine B.,Large, Shannon E.
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p. 2421 - 2424
(2007/10/03)
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- A new methodology for the synthesis of β-amino acids
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A differentially functionalized succinic acid unit 6 undergoes alkylation with excellent regio- and high stereocontrol at the carbon α to the imide to furnish the alkylated product 7 in 60-83% yield. Selective removal of the imide provides 8 in 80-90% yie
- Sibi, Mukund P.,Deshpande, Prasad K.
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p. 1461 - 1466
(2007/10/03)
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- Stereochemistry in enzyme inhibition: Synthesis and evaluation of enantiomerically pure 2-benzyl-3-formylpropanoic acids as inhibitors of carboxypeptidase A
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Both enantiomers of 2-benzyl-3-formylpropanoic acid were synthesized in five steps starting with hydrocinnamic acid and each enantiomer assayed for inhibitory activity against carboxypeptidase A to find that the (R)-form is 674-fold more potent than its e
- Kim, Dong H.,Chung, Suhman
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p. 3769 - 3776
(2007/10/03)
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- Synthetic study of AAL-toxins: Efficient construction of two vicinal diol moieties by asymmetric dihydroxylation
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Asymmetric dihydroxylation has been applied to syntheses of two vicinal anti-diol moieties in key intermediates of AAL-toxins. The strategy allowed efficient construction of left- and right segments of AAL-toxin main chain.
- Oikawa, Hideaki,Kagawa, Takashi,Kobayashi, Tomonori,Ichihara, Akitami
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p. 6169 - 6172
(2007/10/03)
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- Asymmetric hydrogenation of prochiral carboxylic acids and functionalized carbonyl compounds catalysed by ruthenium(II)-binap complexes with aryl nitriles (binap=(R)- or (S)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl)
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Complexes RuCl2(ArCN)2(binap), II (binap=(R)- or (S)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl; ArCN=benzonitrile, a; 2-furancarbonitrile, b; pentafluorobenzonitrile, c) were prepared, and their solution properties were investigated by 31P NMR measurements.The catalytic aactivities and enantioselectivities for IIa-c catalysed hydrogenation of some prochiral acids were very similar to those provided by Ru2Cl4(binap)2(NEt3), I.In the hydrogenation of β-functionalized carbonyl compounds, however, IIa-c showed considerably lower activities and/or selectivities, compared with complex I.The differences in IIa-c catalysed reactions are discussed in relation to the coordinating abilities of ArCN in II.
- Shao, Liming,Takeuchi, Kasumi,Ikemoto, Makoto,Kawai, Toshiyasu,Ogasawara, Masamichi,et al.
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p. 133 - 147
(2007/10/02)
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- Asymmetric hydrogenation of prochiral carboxylic acids catalyzed by the five-coordinate ruthenium(II)-hydride complex PF6 (binap = (R)- or (S)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl)
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The five-coordinate complex PF6 (1, binap = (R)- or (S)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl) has been found to have sufficient catalytic activity for asymmetric hydrogenation of itaconic acid and other prochiral carboxylic acids under mild conditions.The catalytic hydrogenation of itaconic acid by I was examined under a variety of conditions, and the addition of triethylamine was found to effect high enantioselectivities (above 90percent ee). 1H and 31 P NMR examinations of reaction mixtures of I and itaconic acid under conditions similar to the hydrogenation suggested the formation of ruthenium species containing one binap chelate.
- Saburi, Masahiko,Takeuchi, Hiroshi,Ogasawara, Masamichi,Tsukahara, Touru,Ishii, Youichi,et al.
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p. 155 - 167
(2007/10/02)
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- HIGHLY EFFICIENT ASYMMETRIC HYDROGENATION OF ITACONIC ACID DERIVATIVES CATALYZED BY A MODIFIED DIOP-RHODIUM COMPLEX
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A modified DIOP analogue bearing 4-methoxy and 3,5-dimethyl groups on each phenyl group has been synthesized.The rhodium complex of the ligand has been found to give very high optical yields in the asymmetric hydrogenation of itaconic acid and its derivatives bearing β-aryl groups, the products of which are key-intermediates for optically active lignan derivatives.
- Morimoto, Toshiaki,Chiba, Mitsuo,Achiwa, Kazuo
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p. 735 - 738
(2007/10/02)
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- Asymmetric Hydrogenation of Prochiral Alkenes Catalysed by Ruthenium Complexes of (R)-(+)-2,2'-Bis(diphenylphosphino)-1,1'-binaphthyl
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Two chiral ruthenium(II) complexes containing (R)-(+)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl were found to be effective catalysts for the asymmetric hydrogenation of 2-acylaminoacrylic and 2-acylaminocinnamic acids under mild conditions, to afford N-acyl-(R)-α-amino acids with 49 - 95 percent optical purity.The differences between the asymmetric hydrogenations effected by RuII- and RhI-(R)-BINAP systems are discussed.Asymmetric hydrogenation of methylenesuccinic acid and its derivatives with Ru-(R)-BINAP is also described.
- Kawano, Hiroyuki,Ikariya, Takao,Ishii, Youichi,Saburi, Masahiko,Yoshikawa, Sadao,et al.
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p. 1571 - 1575
(2007/10/02)
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- RUTHENIUM(II)-BINAP COMPLEX CATALYZED ASYMMETRIC HYDROGENATION OF UNSATURATED DICARBOXYLIC ACIDS
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Asymmetric hydrogenation of unsaturated dicarboxylic acids employing ruthenium-BINAP complexes as catalyst gave optically active 2-alkylsuccinic acids with high enantioselectivities.
- Kawano, Hiroyuki,Ishii, Youichi,Ikariya, Takao,Saburi, Masahiko,Yoshikawa, Sadao,et. al
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p. 1905 - 1908
(2007/10/02)
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