- An efficient asymmetric biomimetic transamination of α-keto esters to chiral α-amino esters
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An efficient asymmetric biomimetic transamination of α-keto esters with quinine derivatives as chiral bases was described. A wide variety of α-amino esters containing various functional groups can be synthesized in high yield and enantioselectivity.
- Xiao, Xiao,Liu, Mao,Rong, Chao,Xue, Fazhen,Li, Songlei,Xie, Ying,Shi, Yian
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p. 5270 - 5273
(2013/01/15)
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- New anthranilic acid based antagonists with high affinity and selectivity for the human cholecystokinin receptor 1 (hCCK1-R)
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The anthranilic acid diamides represent the most recent class of nonpeptide CCK1 receptor (CCK1-R) antagonists. Herein we describe the second phase of the anthranilic acid C-terminal optimization using nonproteinogenic amino acids containing a phenyl ring in their side chain. The Homo-Phe derivative 2 (VL-0797) enhanced 12-fold the affinity for the rat CCK1-R affinity and 15-fold for the human CCK1-R relative to the reference compound 12 (VL-0395). The eutomer of 2 (6) exhibited a nanomolar range affinity toward the human CCK1-R and was at least 400-fold selective for the CCK1-R over the CCK2-R. Molecular docking in the modeled CCK1-R and its validation by site-directed mutagenesis experiments showed that the 6 binding site overlaps that occupied by the C-terminal bioactive region of the natural agonist CCK. Owing to their interesting properties, new compounds provided by this study represent a solid basis for further advances aimed at synthesis of clinically valuable CCK1-R antagonists.
- Pavan, Michela V.,Lassiani, Lucia,Berti, Federico,Stefancich, Giorgio,Ciogli, Alessia,Gasparrini, Francesco,Mennuni, Laura,Ferrari, Flora,Escrieut, Chantal,Marco, Esther,Makovec, Francesco,Fourmy, Daniel,Varnavas, Antonio
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experimental part
p. 5769 - 5785
(2011/10/09)
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- Asymmetric and efficient synthesis of homophenylalanine derivatives via Friedel-Crafts reaction with trifluoromethanesulfonic acid
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An efficient Friedel-Crafts reaction of TFA-Asp(Cl)-OMe and stoichiometric amounts of benzene was established by using neat trifluoromethanesulfonic acid (TfOH) as solvent and catalyst under a mild condition. This methodology has been applied to many arom
- Murashige, Ryo,Hayashi, Yuka,Hashimoto, Makoto
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supporting information; scheme or table
p. 6566 - 6568
(2009/04/05)
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- Asymmetric petasis reactions catalyzed by chiral biphenols
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Chiral biphenols catalyze the enantioselective Petasis reaction of alkenyl boronates, secondary amines, and ethyl glyoxylate. The reaction requires the use of 15 mol % of (S)-VAPOL as the catalyst, alkenyl boronates as nucleophiles, ethyl glyoxylate as the aldehyde component, and 3 A molecular sieves as an additive. The chiral α-amino ester products are obtained in good yields (71-92%) and high enantiomeric ratios (89:11-98:2). Mechanistic investigations indicate single ligand exchange of acyclic boronate with VAPOL and tetracoordinate boronate intermediates. Copyright
- Lou, Sha,Schaus, Scott E.
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p. 6922 - 6923
(2008/09/21)
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- Concise synthesis and enzymatic resolution of L-(+)-homophenylalanine hydrochloride
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The N-acetyl-homophenylalanine ethyl ester was synthesized by a simple three-step-reaction strategy. L-(+)-homophenylalanine hydrochloride with 98% ee was obtained through a kinetic resolution process using industrial enzyme alcalase. Compared with other
- Zhao, Hua,Luo, Robert G.,Wei, Dean,Malhotra, Sanjay V.
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- Total synthesis of amiclenomycin, an inhibitor of biotin biosynthesis.
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We describe the first synthesis of amiclenomycin, a natural product that has been found to inhibit biotin biosynthesis and, as a consequence, to exhibit antibiotic properties. Structure 1, with a trans relationship between the ring substituents. had previously been proposed for amiclenomycin on the basis of its 1H NMR spectrum. We have prepared the trans and cis isomers 1 and 2 by unequivocal routes and we conclude that the natural product is in fact the cis isomer 2. The properly substituted cyclohexadienyl rings were constructed first. A cycloaddition reaction between 1,2-di(phenylsulfonyl)ethylene and the N-allyloxycarbonyl diene 13, followed by reductive elimination of the phenylsulfinyl groups, gave the cis isomer 15. To obtain the trans isomer, the O-trimethylsilyl diene was used to give the cis hydroxylated Diels-Alder adduct 33, which was transformed into the corresponding trans amino derivative by means of a Mitsunobu reaction. The L-alpha-amino acid functionality was introduced by means of a Strecker reaction on the aldehydes 16 and 42, followed by enzymatic hydrolysis with immobilised pronase.
- Mann, Stephane,Carillon, Sophie,Breyne, Olivier,Marquet, Andree
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p. 439 - 450
(2007/10/03)
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- The synthesis of L-(+)-homophenylalanine hydrochloride
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L-(+)-Homophenylalanine hydrochloride was synthesized from N-phthaloyl-L-(-)-asparitc anhydride 2 in three steps in 55% overall yield with 99% ee. Copyright (C) 2000 Elsevier Science Ltd.
- Xu, Qianyong,Wang, Guoxin,Wang, Xuechao,Wu, Tongxing,Pan, Xinfu,Chan, Albert S.C.,Yang, Teng-Kuei
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p. 2309 - 2314
(2007/10/03)
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- Asymmetric amino acid synthesis: Mitsunobu reaction on chiral cyanohydrins
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BOC(SES)NH was reacted with chiral cyanohydrins using the Mitsunobu reaction to give good yields of protected α-aminonitriles, which were converted to chiral amino and imino acids.
- Decicco, Carl P.,Grover, Paul
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p. 529 - 530
(2007/10/03)
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- Hexa- and heptapeptide anaphylatoxin-receptor ligands
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Oligopeptide compounds or oligopeptide analogue compounds of the formula A-B-D-E-G-J-L-M-Q are ligands for the anaphylatoxin receptor and are useful in the treatment of inflammatory disease states.Also disclosed are anaphylatoxin receptor ligand compositi
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- Variations of the Nature of the Chiral Auxiliary with a Highly Enantioselective Chiral NADH Model
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Various chiral amine alcohols have been used as chiral auxiliares for a highly enantioselective NADH model.Some of these are new reagents which have been obtained by an enzymic resolution method.
- Combret, Yves,Duflos, Jack,Dupas, Georges,Bourguignon, Jean,Queguiner, Guy
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p. 1635 - 1644
(2007/10/02)
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- Synthesis and antitumor activity of platinum(II) complexes containing substituted ethylenediamine ligands
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The synthesis of substituted ethylenediamines, their reactions with K2PtCl4 to give the dichloroplatinum(II) complexes, and the exchange of the chloro ligands for other leaving groups are described.The new compounds have been tested as antitumor agents both in vitro using the hormone independent human mammary carcinoma cell line MDA-MB 231 as well as in vivo using the lymphocytic P388 leukemia of the CD2F1-mouse.In the P388 test, 53 of the 55 tested complexes fulfill the minimum activity of 125percent T/C required for a substance to be active.
- Brunner, Henri,Hankofer, Peter,Holzinger, Ulrich,Treittinger, Barbara,Schoenenberger, Helmut
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