- The Strecker reaction coupled to Viedma ripening: A simple route to highly hindered enantiomerically pure amino acids
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The Strecker reaction is broadly used for the preparation of α-amino acids. However, control of enantioselectivity remains challenging. We here couple the Strecker reaction to Viedma ripening for the absolute asymmetric synthesis of highly sterically hindered α-amino acids. As proof-of-principle, the enantiomerically pure α-amino acids tert-leucine and α-(1-adamantyl)glycine were obtained.
- Baglai, Iaroslav,Leeman, Michel,Wurst, Klaus,Kaptein, Bernard,Kellogg, Richard M.,Noorduin, Willem L.
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supporting information
p. 10832 - 10834
(2018/10/02)
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- Henry reaction catalyzed by new series of imidazolidine-4-one Cu-complexes
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A series of 5-tert-butyl-2-(pyridine-2-yl)imidazolidine-4-ones have been prepared and their Cu(II) complexes studied as enantioselective catalysts of the asymmetric Henry reaction of various aldehydes with nitromethane. It was found that these compounds w
- Drabina, Pavel,Horáková, Eva,R??i?ková, Zdeňka,Sedlák, Milo?
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p. 141 - 147
(2015/02/19)
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- INDAZOLE DERIVATIVES
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This invention relates to compounds, pharmaceutical compositions and methods for the treatment of a condition mediated by CB1 receptor activity in a mammalian subject including a human, which comprises administering to a mammal in need of such treatment a
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- Dynamic kinetic resolution of α-aminonitriles to form chiral α-amino acids
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We have succeeded in the enzymatic synthesis of (R)-α-aminobutyric acid from racemic α-aminobutyronitrile. This has been demonstrated by the use of non-stereoselective nitrile hydratase (NHase) from Rhodococcus opacus 71D, D-aminopeptidase from Ochrobactrum anthropi C1-38 and α-amino-ε- caprolactam (ACL) racemase from Achromobacter obae. Racemic α- aminobutyronitrile was completely converted in 6 h at 30 °C to (R)-α-aminobutyric acid whose optical purity was more than 99%. (S)-α-Aminobutyric acid was also synthesized from α- aminobutyronitrile by NHase, ACL racemase and L-amino acid amidase from Brevundimonas diminuta TPU 5720. In a similar manner, other (R)- or (S)-α-amino acids with more than 97.5% ee could be synthesized from the corresponding α-aminonitriles. This is the first report on the dynamic kinetic resolution (DKR) of α-aminonitriles to form chiral α-amino acids. The key enzyme in this DKR is non-stereoselective NHase, which had been newly screened from soil samples, and its gene cloned. Copyright
- Yasukawa, Kazuyuki,Hasemi, Ryuji,Asano, Yasuhisa
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supporting information; scheme or table
p. 2328 - 2332
(2011/10/19)
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- BENZIMIDAZOLONE DERIVATIVES
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This invention relates to compounds and methods for the treatment of a condition mediated by CB1 receptor activity in a mammalian subject including a human, which comprises administering to a mammal in need of such treatment a therapeutically effective am
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Page/Page column 29
(2009/12/23)
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- Azapeptide derivatives as HIV protease inhibitors
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This invention relates to novel compounds of the Formula Ib: that are azapeptides, and pharmaceutically acceptable salts thereof. More specifically, the invention relates to novel azapeptide compounds that are derivatives of the HIV protease inhibitor atazanavir sulfate. This invention also provides pyrogen-free compositions comprising one or more compounds of the invention and a carrier, and the use of the disclosed compounds and compositions in methods of treating diseases and conditions that are treated by administering HIV protease inhibitors. The invention also relates to the use of one or more of the disclosed compounds as reagents in analytical studies involving atazanavir.
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Page/Page column 40
(2009/01/24)
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- ANTITUMORAL DIHYDROPYRAN-2-ONE COMPOUNDS
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Antitumoral compounds of general formula (I) obtained from a porifera, of the family Raspailiidae, genus Lithoplocamia, species lithistoides, and derivatives thereof are provided.
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Page/Page column 100-101
(2008/06/13)
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- BENZIMIDAZOLONE DERIVATIVES AS CB2 RECEPTOR LIGANDS
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This invention relates to compounds of the formula (I): or pharmaceutically acceptable salts thereof, wherein: A, B, R1, R2 and R3 are each as described herein, and compositions containing such compounds and the use of suc
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Page/Page column 37
(2008/06/13)
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- Process for producing optically active alpha-amino acid and optically active alpha-amino acid amine
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The present invention provides a process for efficiently producing an optically active α-amino acid and an optically active α-amino acid amide. After contacting with cells or processed cells thereof having an ability to asymmetrically hydrolyse, a water solvent is substituted with at least one solvent selected from the group consisting of linear, branched, or cyclic alcohol having 3 or more carbon atoms and the optically active α-amino acid is preferentially precipitated from the alcohol solution. The addition of basic compounds, particularly potassium compounds to the alcohol solution containing the optically active α-amino acid amide, which is obtained after the separation of the optically active α-amino acid, enables the purification of the amide without the inclusion of amino acid into amino acid amide. Thus, the amide is subjected to the step of racemization and then recycled.
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- Method for the preparation of enantiomerically enriched compounds
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Process for the preparation of a diasteromerically enriched phenylglycine amide derivative in which an enantomerically enriched phenylglycine amide is converted into the corresponding Schiff base with the aid of compound R2—C(O)—R3, and the Schiff base obtained is subsequently converted into the diastereomerically enriched phenyglycine amide derivative with the aid of a cyanide source, a reducing agent or an allyl organometallic compound. The phenylglycine amide derivatives obtained are interesting starting materials for the preparation of for example enantimerically enriched α- and or β-amino acids and derivatives thereof, such as amides and esters, and amines.
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- Asymmetric strecker synthesis of α-amino acids via a crystallization-induced asymmetric transformation using (R)-phenylglycine amide as chiral auxiliary
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Matrix presented Diastereoselective Strecker reactions based on (R)-phenylglycine amide as chiral auxiliary are reported. The Strecker reaction is accompanied by an in situ crystallization-induced asymmetric transformation, whereby one diastereomer selectively precipitates and can be isolated in 76-93% yield and dr > 99/1. The diastereomerically pure α-amino nitrile obtained from pivaldehyde (R1 = t-Bu, R2 = H) was converted in three steps to (S)-tert-leucine in 73% yield and >98% ee.
- Boesten, Wilhelmus H. J.,Seerden, Jean-Paul G.,De Lange, Ben,Dielemans, Hubertus J. A.,Elsenberg, Henk L. M.,Kaptein, Bernard,Moody, Harold M.,Kellogg, Richard M.,Broxterman, Quirinus B.
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p. 1121 - 1124
(2007/10/03)
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- Optically active iminocarboxylic acid derivatives
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The compounds of the formula STR1 wherein R is OH, NH2, lower-alkyl-NH or phenyl-lower alkyl-NH are presented. These compounds can be catalytically hydrogenated to the corresponding α-aminocarboxylic acid derivatives which are intermediates in the synthesis of therapeutic pseudopeptides.
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- Molecular Structure of a Chiral 3,5-Bridged Pyridine and the Effect of Structure on Circular Dichroic Spectra
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The crystal structure of the 3,5-bridged chiral macrocyclic pyridine (4S,14S)-4,14-di(2-propyl)-6,9,12-trioxa-3,15,19-triazabicycloheneicosa-1(21),17,19-triene-2,5,13,16-tetrone (5a) has been determined by crystallographic means.Each unit cell contains two nonequivalent molecules.In each molecule the amide groups are twisted out-of-plane in a conrotatory fashion righ-handedly with respect to the molecular C2 axis viewed along the line from C4 to N1 of the pyridine ring.This twist allows avoidance of potential interaction between the amide nitrogen bonded protons and that bonded to C4 of the pyridine ring.The macrocyclic framework is inherently dissymmetric as a result of this helical twist.This is reflected in the circular dichroism spectrum of 5a, which has two strongly negative effects in the 200-400-nm region, at 218 nm, -58800 and 273 nm, -45600.Very similar CD effects are found for analogues of 5a with at the chiral atoms at the 4,14-positions, methyl groups (6a), tert-butyl groups (6b), and proline (7).Comparison are also made with compounds (8b) derived (in thought) from 5a by transposition of the macrocyclic bridge from the 3,5- to the 2,6-positions.Compound 8a is analogous to 8b save that it is a benzene rather than a pyridine derivative.Several nonmacrocyclic analogues of 5a have also been examined as well as the thiamide derivative of 5a (compound 9) for which a synthesis has been developed.The longer wavelength CD effect in 5a is assigned to the pyridine n-?* transition and the shorter wavelength effect to ?-?* transitions.Attempts to correlate the absolute signs with a recently postulated model fail.A method for synthesis of the unnatural amino acids, (S)-(+)-2-amino-3,3,-dimethylbutanoic acid (13), in enantiomerically pure form is described as well as an NMR method for the determination of the enantiomeric purity of samples of 13.
- Speelman, Johanna C.,Talma, Auke G.,Kellogg, Richard M.,Meetsma, A.,Boer, J. L. de,et al.
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p. 1055 - 1062
(2007/10/02)
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- SYSTEMES DE STRECKER ET APPARENTES-XII. CATALYSE PAR LES ALDEHYDES DE L'HYDRATATION INTRAMOLECULAIRE DES α-AMINONITRILES
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Aqueous basic hydration of α-aminopropionitrile is first order either in acetaldehyde (formed by decomposition of α-aminopropionitrile) or different aldehydes added in the medium.The rate determining step involves a rapid preequilibrium in which the catal
- Pascal, R.,Taillades, J.,Commeyras, A.
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p. 2999 - 3008
(2007/10/02)
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