- Preparation method of racemic D/L-tert-leucine
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The invention discloses a preparation method of racemic D/L-tert-leucine, and belongs to the technical field of organic synthesis. Tert-butylpyruvic acid is used as a raw material, and racemic D/L-tert-leucine is obtained through a two-step reaction, wherein in the first step, a Schiff base is generated through a condensation reaction with NH2-P and in the second step, the Schiff base is reduced,deprotection is carried out by using an acid, and the base is adjusted to an isoelectric point to obtain the racemic D/L-tert-leucine. The method is simple and convenient to operate and high in reaction yield, and the purity of the obtained raceme can reach 99% or above.
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Paragraph 0044-0046
(2020/06/20)
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- PROCESS FOR THE PRODUCTION OF N-BOC-2-AMINO-3,3-DIMETHYLBUTYRIC ACID
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The current invention offers a process for the production of N-Boc-2-amino-3,3-dimethylbutyric acid by a reaction of tert-Leucine with di-tert-butyl-dicarbonate, the process comprising (i) contacting the tert-Leucine with di-tert-butyl-dicarbonate in an aqueous medium, opti0nally comprising a first organic solvent, in the presence of an inorganic base, (ii) optionally removing the first organic solvent, (iii) optionally extracting the resulting N-Boc-2-amino-3,3-dimethylbutyric acid into a second organic solvent, (iv) isolating the product by precipitation from the reaction mixture at acidic p H, and (v) optionally reuse the first and/or second organic solvents recovered from step (ii) and/or step (iv) for the next production cycle. The process is sufficiently short, uses preferably environmental friendly solvents, avoids waste and leads to good yields.
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Page/Page column 10
(2018/06/12)
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- PROCESS FOR PRODUCTION OF N-ALKOXYCARBONYL-tert-LEUCINES
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A high quality N-alcoxycarbonyl-tert leucine can be efficiently and stably produced with an easy procedure by reacting tert-leucine with an N-alcoxycarbonylating agent in the presence of water, wherein the use amount of the N-alcoxycarbonylating agent is not less than 0.90 times by mole and not more than 1.00 times by mole relative to the tert-leucine, with maintaining the pH of the reaction mixture in the range of not less than 9 and not more than 13 using a basic agent. In addition, an N-alcoxycarbonyl-tert-leucine can be efficiently extracted from the basic aqueous solution thereof under a mild condition using a water-immiscible solvent by mixing a hydroxide. Furthermore, the two crystal forms of N-butoxycarbonyl-tert-leucine can be controlled by adjusting the water amount in crystallization step, and the compound can be stably produced in an industrial production.
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Page/Page column 14
(2012/03/26)
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- HCV NS-3 serine protease inhibitors
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HCV inhibitors, compositions comprising these compounds as active ingredient, as well as processes for preparing these compounds, having the formula I wherein A is
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- Potassium channel openers
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Compounds of formula I: are useful in treating diseases prevented by or ameliorated with potassium channel openers. Also disclosed are potassium channel opening compositions and a method of opening potassium channels in a mammal.
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- Potassium channel openers
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Compounds of formula I: are useful in treating diseases prevented by or ameliorated with potassium channel openers. Also disclosed are potassium channel opening compositions and a method of opening potassium channels in a mammal.
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