202280-02-2Relevant academic research and scientific papers
Enantiomeric discrimination of cyclic β-amino acids using (18-crown-6)-2,3,11,12-tetracarboxylic acid as a chiral NMR solvating agent
Chisholm, Cora D.,Fueloep, Ferenc,Forro, Eniko,Wenzel, Thomas J.
experimental part, p. 2289 - 2294 (2010/11/05)
(18-Crown-6)-2,3,11,12-tetracarboxylic acid is an excellent chiral NMR solvating agent for cyclic β-amino acids with cyclopentane, cyclohexane, cycloheptane, cyclopentene, cyclohexene, bicyclo[2.2.1]heptane, and bicyclo[2.2.1]heptene rings. The crown ether was added to the neutral β-amino acids in methanol-d4. A neutralization reaction between the crown ether and β-amino acid forms the ammonium ion needed for favorable association. Enantiomeric discrimination of the two hydrogen atoms α to the amine and carboxylic acid moieties of the β-amino acid was observed with every substrate studied. Trends in the order of the enantiomeric discrimination of certain hydrogen atoms for substrates of similar structures correlate with the absolute configuration.
PEPTIDES AND PEPTIDOMIMETIC COMPOUNDS, THE MANUFACTURING THEREOF AS WELL AS THEIR USE FOR PREPARING A THERAPEUTICALLY AND/OR PREVENTIVELY ACTIVE PHARMACEUTICAL COMPOSITION
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, (2010/04/25)
Peptides, peptidomimetics and derivatives thereof of the general formula I: H2N-GHRPX1-β-X4X5X6X7X8X9X10-X11 (I), in which X1-X10 denote one of the 20 genetically coded amino acids, wherein X8, X9 and X10 may also denote a single chemical bond;X11 denotes OR1 in which R1 equals hydrogen or (C1-C10) alkyl NR2R3 with R2 and R3 are equal or different and denote hydrogen, (C1-C10) alkyl, or a residue —W-PEG5-60K, in which the PEG residue is attached via a suitable spacer W to the N-atom, ora residue NH—Y-Z-PEG5-60K, in whichY denotes a chemical bond or a genetically coded amino acids from the group S, C, K or R andZ denotes a spacer, via which a polyethylene glycol (PEG)-residue can be attached, and their physiologically acceptable salts, andβ denotes an amino acid, or a peptidomimetic element, which induces a bend or turn in the peptide backbone.
Vapour-assisted enzymatic hydrolysis of β-lactams in a solvent-free system
Forro, Eniko,Fueloep, Ferenc
, p. 1005 - 1009 (2008/09/21)
A new, solvent-free, vapour-assisted method, developed for the synthesis of carbocyclic cis β-amino acid enantiomers through the Candida antarctica lipase B-catalysed enantioselective (E >200) hydrolysis of β-lactams with 0.5 equiv of H2O at 70 °C, has been demonstrated to be applicable on a preparative scale to produce (±)-2 (the starting racemate for cispentacin), (±)-3 (the starting racemate for 4-tert-butylcispentacin, a new cispentacin analogue) and (±)-7 (the starting racemate for 1,4-ethylene-bridged cispentacin).
Synthesis of enantiopure 1,4-ethyl- and 1,4-ethylene-bridged cispentacin by lipase-catalyzed enantioselective ring opening of β-lactams
Forro, Eniko,Fueloep, Ferenc
, p. 573 - 575 (2007/10/03)
1,4-Ethyl- and 1,4-ethylene-bridged cispentacin enantiomers 1a, 1c and 2a, 2c were prepared through the lipase-catalyzed enantioselective ring opening of racemic exo-3-azatricyclo[4.2.1.02.5]nonan-4-one, (±)-1, and exo-3-azatricyclo[4.2.1.02.5]non-7-en-4-one, (±)-2. High enantioselectivity (E >200) was observed when the Lipolase-catalyzed reactions were performed with 1equiv of H2O in diisopropyl ether at 70°C. The resolved β-amino acids 1a and 2a (yield 46%) and β-lactams 1b and 2b (yield≥40%) could be easily separated. The ring opening of lactam enantiomers with 18% HCl afforded the corresponding β-amino acid hydrochloride enantiomers (ee ≥98%).
An alkaloid-mediated desymmetrization of meso-anhydrides via a nucleophilic ring opening with benzyl alcohol and its application in the synthesis of highly enantiomerically enriched β-amino acids
Zhang, Mingbao,Zhu, Lei,Ma, Xin
, p. 3455 - 3468 (2007/10/03)
The cinchona alkaloid-mediated opening of prochiral cyclic anhydrides in the presence of benzyl alcohol leading to optically active hemiesters is described. Structurally diverse anhydrides are converted into their corresponding benzyl monoesters with either enantiomer being obtained with up to 99 percent e.e. by using quinine or quinidine as the directing additive. A simple aqueous work-up protocol permits the isolation of the products in analytically pure form and the recovery of the alkaloids almost quantitatively. These hemiesters can be converted to N-protected β-amino esters by means of Curtius degradation of the corresponding acyl azides. Subsequent cleavage of both protecting groups by a single reaction step leads to the free β-amino acids in excellent yields. The efficiency of this procedure is demonstrated by the short asymmetric synthesis of the fungicide cis-pentacin delivering the amino acid with >99.7 percent enantiomeric excess.
5-Fluorouracil derivatives, and their pharmaceutical compositions
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, (2008/06/13)
A compound of the formula: STR1 wherein R is a bridged alicyclic group selected from the group consisting of norbornyl, norbornenyl, bicyclo[2,2,2]-heptyl and adamantyl optionally substituted by at least one substituent selected from the group consisting
