- Practical and efficient utilisation of (R)-3-chloro-1,2-propanediol in synthesis of L-carnitine
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As a by-product originating from Salen Co(III) catalysed hydrolytic kinetic resolution (HKR) of (±)-epichlorohydrin in the manufacturing procedure of L-Carnitine, (R)-3-chloro-1,2-propanediol was utilised as a starting chiral material to prepare via key nitrile intermediates and by a final hydrolysis L-Carnitine. The new synthetic approach demonstrated an efficient utilisation of the by-product.
- Yang, Yunxu,Wang, Weili,Wumaier, Aikeremu,Sheng, Ruilong,Zhang, Xuetao,Zhang, Tianyi
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scheme or table
p. 371 - 372
(2011/10/09)
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- PROCESS FOR PRODUCING CARNITINAMIDE
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[PROBLEMS] To provide a process in which in the production of carnitinamide as a production intermediate for L-carnitine, carnitine nitrile can be hydrated into carnitinamide with high selectivity so that high-purity carnitinamide excelling as a substrate for optical resolution or microbial stereoselective hydrolysis can be produced in high yield. [MEANS FOR SOLVING PROBLEMS] There is provided a process comprising hydrating carnitine nitrile into carnitinamide with the use of a catalyst containing manganese oxide to thereby realize production of carnitinamide containing substantially none of carnitine by-products in high yield. As a result, carnitinamide of extremely high purity can be produced through simple and easy crystallization operation.
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Page/Page column 7-8; 11; 1/1
(2008/06/13)
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- Lipase-catalyzed enantiomer separation of 3-hydroxy-4-(tosyloxy) butanenitrile: Synthesis of (R)-GABOB (=(3R)-4-amino-3-hydroxybutanoic acid) and (R)-carnitine hydrochloride (= (2R)-3-carboxy-2-hydroxy-N,N,N-trimethylpropan- 1-aminium chloride)
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Enzymatic resolution of racemic 3-hydroxy-4-(tosyloxy)butanenitrile ((±)-5) by using various lipases in different solvents were studied. The obtained optically pure (3R)-3-(acetyloxy)-4-(tosyloxy)-butanenitrile ((R)-6), upon treatment with aqueous ammonia followed by cone. HCl solution, provided (R)-GABOB (=(3R)-4-amino-3-hydroxybutanoic acid; (R)-1). Similarly, reaction of (R)-6 with aqueous trimethylamine solution followed by cone. HCl solution provided (R)-carnitine hydrochloride (=(2R)-3-carboxy-2-hydroxy-N,N,N- trimethylpropan-1-aminium chloride; (R)-2·HCl) in an expeditious manner.
- Kamal, Ahmed,Khanna, G. B. Ramesh,Krishnaji, Tadiparthi
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p. 1723 - 1730
(2008/03/12)
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- Process for preparing optically active carnitine ester
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A process for preparing an optically active carnitine ester represented by formula (I): wherein R represents a lower alkyl group; and X represents a halogen atom, is disclosed, comprises asymmetrically hydrogenating a γ-trimethylammonium-3-oxobutanoic ester halide represented by formula (II): wherein R and X are as defined above, in the presence of a ruthenium-optically active phosphine complex as a catalyst. An optically active carnitine ester of any desired isomerism can be obtained through simple operation in high yield at high optical purity. The substrate used is easily available.
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- An efficient synthesis of (R)-carnitine
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An efficient synthesis of (R)-carnitine hydrochloride is described. The starting material is obtained by microbial resolution of (RS)-2,3-dichloro-1-propanol.
- Kasai,Sakaguchi
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p. 1211 - 1212
(2007/10/02)
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- Process for preparing carnitine
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A process for preparing carnitine which comprises asymmetrically hydrogenating a γ-halogeno-β-keto ester represented by formula (I): STR1 wherein X represents a chlorine atom or a bromine atom; and R represents a lower alkyl group, in the presence of a ruthenium-optically active phosphine complex represented by formula (II), (III) or (IV): wherein L represents 2,2'-bis(di-p-R1 -phenylphosphino)- 1,1'-binaphthyl of formula (III): STR2 wherein R1 represents a hydrogen atom, a methyl group, or a t-butyl group; R2 represents a lower alkyl group or a trifluoromethyl group; and X is as defined above, as a catalyst at a temperature of from 70° to 150° C. to obtain an optically active alcohol represented by formula (VI): STR3 wherein X and R are as defined above, and then reacting the optically active alcohol as obtained with trimethylamine without isolation, is disclosed.
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- Process for the preparation of L(-)carnitine hydrochloride and of L(-)carnitine inner salt
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The invention refers to a process for the preparation of L(-)carnitine by using dibenzoyl-D(31 )tartaric acid and crystallizating the relative salt at low temperature.
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- Process for preparing L-carnitine and salts thereof
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L-carnitine and salts thereof are resolved from DL-carnitine by the use as a resolving agent of dibenzoyl-L(+)tartaric acid. L-carnitine is known as vitamin BT and is useful as a medicine.
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