- Changing stereoselectivity and regioselectivity in copper(i)-catalyzed 5-: Exo cyclization by chelation and rigidity in aminoalkyl radicals: Synthesis towards diverse bioactive N-heterocycles
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The work reveals that a chelate-Type interaction in the transition state of a β-Aminoalkyl radical in a copper(i)-catalyzed 5-exo-Trig radical cyclization step changes the usual stereochemistry of the NH-pyrrolidine ring predicted by the Beckwith-Houk transition state model. In contrast, the rigidity in the fused β-Aminoalkyl radical changes the Baldwin's predicted 5-exo to 6-endo cyclization mode, preferentially forming a piperidine ring over a pyrrolidine ring via a geometrically constrained transition state. The resultant diverse NH-pyrrolidines, pyrrolines and piperidines are sources of the bioactive natural product roseophilin and the drug Ritalin among others.
- Sadanandan, Sandhya,Gupta, Dharmendra Kumar
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p. 3350 - 3365
(2020/03/06)
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- AN IMPROVED PROCESS FOR THE PREPARATION OF DEXMETHYL PHENIDATE HYDROCHLORIDE
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Disclosed herein a process for the preparation of highly pure dexmethylphenidate hydrochloride (Formula-I) which comprises the steps of neutralization of dl- threomethylphenidate hydrochloride to dl-threo methylphenidate; subsequent resolution of dl-threo methylphenidate using amino acid or its derivatives as chiral resolution agent to yield dexmethylphenidate salt; hydrolysis of the salt and further conversion of dexmethylphenidate into its hydrochloride salt.
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- IMPROVEMENTS IN OR RELATING TO ORGANIC MATERIAL
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The invention provides a method for the preparation of an intermediate for use in synthesizing a lower alkyl phenidate compound of formula (I), wherein each R1 independently represents an optionally substituted aryl, heteroaryl, alkyl, cycloalkyl, alkoxy, aryloxy, acyl, carboxyl, hydroxyl, halogen, amino, nitro, sulfo or sulfhydryl group, R2 represents a hydrogen atom or a lower alkyl group, n represents an integer from 1 to 5 and m represents an integer from 1 to 3 or a pharmaceutically acceptable salt thereof; which method comprises the steps of: (a) flowing a tosylhydrazone compound of formula (IV), wherein R1, n and m are as defined above in relation to the methylphenidate of formula (I), an organic base and an organic solvent into a fluidic network; and (b) reacting the tosylhydrazone compound of formula (IV) and the base in the fluidic network under thermal and/or photochemical conditions to form a transient diazoamide compound of formula (V), wherein R1, n and m are as defined above in relation to the methylphenidate of formula (I).
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Paragraph 0056; 0057
(2018/04/13)
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- PROCESS FOR THE PREPARATION OF METHYLPHENIDATE AND PHARMACEUTICAL SALTS THEREOF
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The present invention is directed to an improved process for the preparation of methylphenidate, stereoisomer, mixture of stereoisomers and pharmaceutically acceptable salts thereof, more particularly, the sulfate and hydrochloride salts of methylphenidate, di-threo-methylphenidate and dex-methylphenidate. Methods of removing or reducing the amount of impurities from the above described process are also disclosed.
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Page/Page column 0345-0347
(2015/05/26)
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- LOW-TEMPERATURE SYNTHESIS OF METHYLPHENIDATE HYDROCHLORIDE
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The present invention describes a process for the preparation of methylphenidate hydrochloride. The process involves the esterification of ritalinic acid and methanol in the presence of an acid catalyst at a low temperature. The process may optionally involve the addition of an orthoester.
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Page/Page column 25
(2012/06/30)
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- PROCESS FOR PREPARING METHYL PHENIDATE HYDROCHLORIDE
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Disclosed herein is a process for the preparation of methyl phenidate hydrochloride (Formula I), comprising the steps of; hydrolyzing α-phenyl-α-pipyridyl acetamide (Formula II) in presence of mineral acid at reflux temperature and subsequent neutralization to yield threo -α-phenyl-α-pipyridyl-2-acetic acid (Formula III) which in presence of acidic catalyst reacts with methanol followed by treatment with alcoholic hydrochloride solution produces methyl phenidate hydrochloride.
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Page/Page column 6
(2011/06/25)
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- Synthesis of Methylphenidate and Analogs Thereof
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A synthetic process for the preparation of amino acid esters such as methylphenidate and analogs thereof is disclosed. The process involves reacting an amino acid such as α-phenyl-α-(2-piperidinyl)acetic acid or an analog thereof with an alcohol such as methanol in the presence of an acid and a water sequestrant such as trimethyl orthoacetate. In some embodiments, the water sequestrant is added to the reaction mixture after an initial period of esterification and then the reaction is allowed to continue. The α-phenyl-α-(2-piperidinyl)acetic acid methyl ester or analog thereof is then isolated from the reaction mixture. In one variation of the process, the supernatant liquid may be recycled in subsequent runs to increase yield and product purity.
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Page/Page column 6-7
(2010/08/03)
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- An improved manufacturing process for methylphenidate and intermediates thereof
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The present invention discloses selective and complete reduction of pyridine ring in a biaryl system comprising α-substituted or non-substituted benzene ringand relates more specifically, not exclusively, for the manufacture of methylphenidate, which is used for treatment of Attention Deficit Hyperactive Disorder (ADHD) and also acts as central nervous system stimulant, by using palladium/C in a solvent such as C1-C4 alcohols in presence of molar quantities of organic and/or inorganic acids.
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Page/Page column 4-5
(2008/06/13)
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- Manufacturing process for methyl phenidate and intermediates thereof
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The present invention discloses selective and complete reduction of pyridine ring in a biaryl system comprising ∝-substituted or nonsubstituted benzene ring and relates more specifically, not exclusively, for the manufacture of methylphenidate, which is used for treatment of Attention Deficit Hyperactive Disorder (ADHD) and also acts as central nervous system stimulant, by using palladium/C in a solvent such as C1-C4 alcohols in presence of molar quantities of organic and/or inorganic acids.
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Page/Page column 3
(2008/06/13)
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- Method to separate stereoisomers
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A method to resolve the stereoisomers of an optically active compound comprising an amine moiety. The method provides a mixture comprising two stereoisomers of a compound comprising a amine moiety. The method supplies l-fenchyloxyacetic acid, treats the mixture of stereoisomers with that l-fenchyloxyacetic acid, and collects one of those two stereoisomers having greater than a 99 percent enantiomeric excess.
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Page/Page column 4
(2010/02/13)
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- Process for the preparation of threo-methylphenidate hydrochloride
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The present invention provides a process for the preparation of threo-methylphenidate hydrochloride. According to a preferred embodiment, the process comprises the following steps: (a) contacting 1-(phenylglyoxylyl)piperidine arenesulfonylhydrazone of the formula wherein Ar denotes an aryl group, where the aryl group may be substituted by a C1-C6 alkyl, halo or nitro group; with an inorganic base in the presence of a water immiscible organic solvent and a phase transfer catalyst to obtain (R*,R*)-enriched 7-phenyl-1-azabicyclo[4.2.0]octan-8-one of the formula: (b) reacting the (R*,R*)-enriched 7-phenyl-1-azabicyclo[4.2.0]octan-8-one prepared in step (a) with a solution of hydrogen chloride in methanol to obtain threo-enriched methylphenidate hydrochloride; (c) crystallizing the threo-enriched methylphenidate hydrochloride prepared in step (b) to give the desired threo-methylphenidate hydrochloride. Preferably, the threo-methylphenidate hydrochloride produced by the process of the present invention contains no more than 1% of the erythro-isomer.
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Page/Page column 5-6
(2008/06/13)
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- Process for preparing the d-threo isomer of methylphenidate hydrochloride
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A process for preparing the +E,uns d+EE -threo isomer of methylphenidate hydrochloride comprising converting +E,uns d,l+EE -threo methylphenidate hydrochloride to the free base form in a first step, resolving the free base prepared in the first step with (R)-(-)-1,1'-binaphthyl-2,2'-diyl hydrogen phosphate to obtain the phosphate salt enriched with the +E,uns d+EE -threo isomer of methylphenidate in a second step, basifying the phosphate salt to obtain the free base form of the +E,uns d+EE -threo isomer of methylphenidate in a third step, converting the free base to the hydrochloride salt form of the +E,uns d+EE -threo isomer of methylphenidate in high optical purity in a fourth step, and recrystallizing the hydrochloride salt form to obtain the desired +E,uns d+EE -threo isomer in a higher optical purity. An alternative embodiment relates to the preparation of the +E,uns d+EE -threo isomer of methylphenidate hydrochloride utilizing the hydrochloride salt form of the racemic mixture of threo-methylphenidate directly.
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