- An Improved and Efficient Process for the Production of Highly Pure Dexmethylphenidate Hydrochloride
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The present work describes an efficient and commercially viable process for the synthesis of dexmethylphenidate hydrochloride (1), a mild nervous system stimulant. The overall yield is 23% with ~99.9% purity (including seven chemical steps). Formation and control of possible impurities are also described in this report.
- Xing, Long-Xuan,Shen, Cheng-Wu,Sun, Yuan-Yuan,Huang, Lei,Zheng, Yong-Yong,Li, Jian-Qi
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- PROCESSES AND INTERMEDIATES FOR PREPARING 2-SUBSTITUTED PIPERIDINE STEREOISOMERS
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A process for preparing d-threo methyl ±- piperid-2-ylarylacetates of formula III: wherein R 1 is aryl having 6 to 28 carbon atoms, comprising the steps of: reacting a pyridine having formula I: wherein R 1 is aryl having 6 to 28 carbon atoms with hydrogen in an alkanoic acid having 1 to 10 carbon atoms and in the presence of a catalyst to provide a mixture of threo and erythro piperidine stereoisomers having formulas IIa-d: €?€?€? adding an alkyl alkanoate having 2 to 20 carbon atoms to said mixture, thereby precipitating alkanoate salts of said erythro stereoisomers preferentially with respect to alkanoate salts of said threo stereoisomers; reacting said erythro alkanoate salts with aqueous base to form said erythro stereoisomers; reacting said erythro stereoisomers with an acid resolving agent in an alkyl alcohol having 1 to 5 carbon atoms, thereby forming acid salts of said 1-erythro stereoisomers preferentially with respect to said d-erythro stereoisomers; reacting said 1-erythro acid salts with aqueous base to form said 1-erythro piperidine; reacting said 1-erythro piperidine with an alkali metal alkoxide having one to 10 carbon atoms in organic solvent, whereby forming said d-threo piperidine, and converting said d-threo piperidine to said d-threo methyl ±- piperid -2- ylarylacetate.
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(2008/06/13)
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- METHOD FOR THE PRODUCTION OF D-THREO-2-PHENYL-2-PIPERIDINE-2-YL ACETATES
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Disclosed is a method for producing d-threo-[R(R*,R*)]-2-phenyl-2-piperidine-2-yl acetate and the acid addition salts thereof by converting d-threo-[R(R*,R*)]-2-phenyl-2-piperidine-2-yl ethanoic acid or an acid addition salt thereof into the corresponding
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- Methods for production of piperidyl acetamide stereoisomers
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Synthetic methods are provided comprising the steps of racemizing l-threo-piperidyl acetamides to form a mixture of d-threo, l-threo, d-erythro, and l-erythro-piperidyl acetamides by reacting said l-threo-piperidyl acetamides with alkanoic acid.
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- Processes and intermediates for resolving piperidyl acetamide stereoisomers
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Processes and intermediates for preparing 2-substituted piperidines such as 2-substituted d-threo piperidines are provided, including processes and intermediates for resolution of piperidyl acetamide stereoisomers.
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