- Chiral lithium binaphtholate for enantioselective amination of acyclic α-alkyl-β-keto esters: Application to the total synthesis of L-carbidopa
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A chiral lithium binaphtholate catalyzes the enantioselective amination of α-alkyl-β-keto esters with azodicarboxylates to produce optically active α,α-disubstituted α-amino acid derivatives in high yields and with good to high enantioselectivities. A stoichiometric amount of lithium hydroxide efficaciously improved both the reactivity and enantioselectivity of amination. The resulting aminated product is readily convertible to L-carbidopa.
- Asano, Toshifumi,Moritani, Miyuki,Nakajima, Makoto,Kotani, Shunsuke
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p. 5975 - 5982
(2017/09/18)
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- Method for synthesizing Carbidopa
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The invention belongs to the field of chemical synthesis and particularly relates to a method for synthesizing Carbidopa. The method is characterized by subjecting Oxaziridine to a reaction with methyldopate so as to produce imide methyldopate, and then, carrying out hydrolysis, thereby producing the Carbidopa. The method has the advantages that the Carbidopa is prepared by adopting a bran-new process route, all the raw materials used are suitable for pharmaceutical synthesis, and the prepared Carbidopa is high in yield and good in product quality.
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Paragraph 0033; 0034
(2016/12/01)
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- Synthesis of dendrimer-type chiral stationary phases based on the selector of (1S,2R)-(+)-2-amino-1,2-diphenylethanol derivate and their enantioseparation evaluation by HPLC
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In our recent work, a series of dendritic chiral stationary phases (CSPs) were synthesized, in which the chiral selector was L-2-(p-toluenesulfonamido)-3- phenylpropionyl chloride (selector I), and the CSP derived from three-generation dendrimer showed the best separation ability. To further investigate the influence of the structures of dendrimer and chiral selector on enantioseparation ability, in this work, another series CSPs (CSPs 1-4) were prepared by immobilizing (1S,2R)-1,2-diphenyl-2-(3-phenylureido)ethyl 4-isocyanatophenylcarbamate (selector II) on one- to four-generation dendrimers that were prepared in previous work. CSPs 1 and 4 demonstrated the equivalent enantioseparation ability. CSPs 2 and 3 showed the best and poorest enantioseparation ability respectively. Basically, these two series of CSPs exhibited the equivalent enantioseparation ability although the chiral selectors were different. Considering the enantioseparation ability of the CSP derived from aminated silica gel and selector II is much better than that of the one derived from aminated silica gel and selector I, it is believed that the dendrimer conformation essentially impacts enantioseparation.
- He, Bao-Jiang,Yin, Chuan-Qi,Li, Shi-Rong,Bai, Zheng-Wu
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experimental part
p. 69 - 76
(2010/09/09)
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- PROCESS FOR THE PREPARATION OF CARBIDOPA
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The invention relates to a process for the preparation of (-) - (L) -3- (3,4-dihydroxyphenyl) -2-hydrazino-2 -methyl propionic acid (carbidopa) of the formula (II) by using 3, 3 -pentamethylene oxaziridine of the formula (IV), which comprises reacting L-α-methyldopa methyl ester of the formula (III) with 3,3-penta- methylene oxaziridine of the formula (IV), isolating the thus-obtained (+) - (L) -2- (N' - cyclohexylidene-hydrazino) -3- (3 , 4-dihydroxy phenyl) -2 -methyl propionic acid methyl ester of the formula (I) (I) and subjecting it to hydrolysis with an acid. (+) - (L) -2- (N' -cyclohexylidene-hydrazino) -3-(3,4-dihydroxyphenyl) -2-methyl propionic acid methyl ester of the formula (I) is a new intermediate . (-) - (L)-3-(3,4-dihydroxyphenyl) -2-hydrazino-2- methyl propionic acid (carbidopa) of the formula (XI) thus obtained is a valuable therapeutic active ingredient having the international non-proprietary name carbidopa.
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Page/Page column 21
(2008/06/13)
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- Kinetic study of the reaction of pyridoxal 5'-phosphate with hydrazino compounds of pharmacological activity
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The kinetics of the reaction between pyridoxal 5'-phosphate (PLP) with carbidopa, hydralazine, and isoniazid, in aqueous solution at variable pH and constant ionic strength of 0.1M was studied spectrophotometrically. The rate constants of formation and hydrolysis of the resulting Schiff base, and its stability were determined in a wide range of pH. A comparison is made of the formation rate constants with those of PLP with hydrazine. The reactivity shows the sequence isoniazid > hydrazine > carbidopa > hydralazine in the whole range of pH studied. The Schiff bases studied are more stable than those formed by PLP and hexylamine and as stable as those described for the reactions of PLP with poly(L-lysine) or copolypeptides containing L-lysine.
- Echevarria-Gorostidi,Basagoitia,Pizarro,Goldsmid,Blanco,Blanco
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p. 837 - 844
(2007/10/03)
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- Purification process
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The p-toluene sulfonic acid addition salt of α-hydrazino-α-methyl-β-(3,4-dihydroxyphenyl)propionic acid is formed to readily allow crystallization of the product from solution. The acid addition salt may be dissolved and then neutralized to obtain the fre
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