- PROCESS FOR THE PRODUCTION OF CARNITINE BY CYCLOADDITION
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The invention relates to a method for the production of L-carnitine, wherein a chiral β-lactone carnitine precursor is obtained by a [2+2] cycloaddition of ketene with an aldehyde X—CH2—CHO, wherein X is selected from Cl, Br, I and trimethylamine, in the presence of a chiral catalyst.
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Page/Page column 10
(2012/02/03)
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- An efficient, highly enantioenriched route to L-carnitine and α-lipoic acid via hydrolytic kinetic resolution
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A general and practical approach for the synthesis of C-4 chiral building blocks using Jacobsen's hydrolytic kinetic resolution technique to resolve terminal epoxides and diols in high enantiomeric excess and excellent yields is described. The utilization of these building blocks for the synthesis of biologically important natural products L-carnitine and α-lipoic acid is illustrated. Georg Thieme Verlag Stuttgart.
- Bose, D. Subhas,Fatima, Liyakat,Rajender, Salla
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p. 1863 - 1867
(2008/01/27)
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- Asymmetric synthesis of (S)-(+)-carnitine and analogs
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A general asymmetric route to enantiomerically pure (S)-(+)-carnitine and analogs has been investigated that involves mono-addition of organometallic reagents to the lactone carbonyl group of (5R,6S)-4-(benzyloxycarbonyl)-5,6-diphenyl-2,3,5,6-tetrahydro-4H-1,4-oxazin- 2-one and Lewis acid promoted stereoselective allylation of the resulting hemiacetals. The diastereomerically pure allyl oxazines thus obtained were readily converted into enantiomerically pure (S)-(+)-carnitine and two substituted analogs.
- Jain, Rajendra P,Williams, Robert M
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p. 6505 - 6509
(2007/10/03)
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- Retention and selectivity of teicoplanin stationary phases after copper complexation and isotopic exchange
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Teicoplanin is a macrocyclic glycopeptide that is highly effective as a chiral selector for LC enantiomeric separations. Two possible interaction paths were investigated and related to solute retention and selectivity: (1) interactions with the only teicoplanin amine group and (2) role of hydrogen bonding interactions. Mobile phases containing 0.5 and 5 mM copper ions were used to try to block the amine group. In the presence of copper ions, it was found that the teicoplanin stationary phase has a decreased ability to separate most underivatized racemic amino acids. However, it maintained its ability to separate enantiomers that were not α - amino acids. It is established that there is little copper - teicoplanin complex formation. The effect of Cu2+ on the enantioseparation of some α - amino acids appears to be due to the fact that these solutes are good bidentate ligands and form complexes with copper ions in the mobile phase. Isotopic exchange with deuterium oxide was performed using acetonitrile - heavy water mobile phases. It was found that the retention times of all amino acids were lower with deuterated mobile phases. The retention times of polar or apolar molecules without amine groups were higher with deuterated mobiles phases. In all cases, the enantio-selectivity factors were unaffected by the deuterium exchange. It is proposed that the electrostatic interactions are decreased in the deuterated mobile phases and the solute-accessible stationary-phase volume is somewhat swollen by deuterium oxide. The balance of these effects is a decrease in the amino acid retention times and an increase in the apolar solute retention time. The enantio-selectivity factors of all of the molecules remain unchanged because all of the interactions are changed equally. We propose a new global quality criterion (the E factor) for comparing and evaluating enantiomeric separations.
- Berthod,Valleix,Tizon,Leonce,Caussignac,Armstrong
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p. 5499 - 5508
(2007/10/03)
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- Phosphinyloxy propanaminium inner salt derivatives
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Compounds of the formula STR1 where X1 and X2 are independently O or S, and R1 is as defined in the description R2, R3, and R4 are each independently straight or branched chain (C1-4)alkyl, and pharmaceutically acceptable salts, physiological hydrolysable esters, and pro-drug forms thereof are useful as hypoglycemic agents.
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- Process for preparing phosphinyloxy propanaminium inner salt derivatives
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A process for preparing compounds of the formula STR1 where X1 and X2 are independently O or S, and R1 is as defined herein, R2, R3, and R4 are each independently straight or branched chain (C1-4)alkyl, and pharmaceutically acceptable salts, physiological hydrolyzable esters, and pro-drug forms thereof, which are useful as hypoglycemic agents.
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- A new, short and efficient synthesis of both enantiomers of carnitine
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A short, efficient and enantioselective synthesis of both (R) and (S) enantiomers of carnitine is reported starting with (R) or (S) malic acid and involving a chemoselective reduction step.
- Bellamy,Bondoux,Dodey
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p. 7323 - 7326
(2007/10/02)
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- ON THE STERIC COURSE OF BAKER' S YEAST MEDIATED REDUCTION OF ALKYL 4-AZIDO-AND 4-BROMO-3-OXOBUTYRATE. SYNTHESIS OF (R)- AND (S)-CARNITIN
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Baker's yeast reduction of ethyl 4-azido-and 4-bromo-3-oxobutyrate affords (3R) (8) and (3S) (2), respectively, in high optical purity.
- Fuganti, Claudio,Grasselli, Piero
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p. 101 - 104
(2007/10/02)
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