19262-68-1

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Asymmetric functionalization of the C(sp3)-H bond is an attractive yet challenging strategy to achieve versatile bond-forming events, enabling the precise assembly of molecular complexity with minimal manipulation of functional groups. Here, we report an asymmetric C(sp3)-H/C(sp3)-H umpolung coupling of N-allylimine and coordinating α-aryl carbonyls by using chiral phosphoramidite-palladium catalysis. A wide variety of α-heteroaryl ketones and 2-acylimidazoles are nicely tolerated to open a convenient and tunable avenue for efficient synthesis of enantioenriched β-amino-γ,δ-unsaturated carbonyl derivatives with high levels of regio- and stereoselectivities, capable of providing a key intermediate for asymmetric synthesis of Focalin. This protocol showcases an umpolung reactivity of the N-allylimines through a concerted proton and two-electron transfer process to cleave the allylic C-H bond, effectively complementing established methodology for allylic C-H functionalization. An inner-sphere allylation pathway for both α-heteroaryl carbonyls and 2-acylimidazoles to attack the π-allylpalladium species is suggested by computational studies and experimental facts, wherein the nitrogen coordination to the palladium center enables the preference of branched regioselectivity.

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.

, The product is prepared by reacting. tartaric acid and oxalyl chloride as raw materials under the action of an acid-binding agent and D - can be used as a chiral resolution agent for chiral medicine, the preparation method of the product is simple, in a polar solvent . and the chiral resolution is, The method is high, purity.

The invention relates to a new synthetic route of dexmethylphenidate. Methyl phenylacetate serves as a raw material, and the dexmethylphenidate is synthesized at high yield through four steps of an amidation reaction, a diazotization reaction, a cyclization reaction and a rearrangement reaction. The preparation method of the dexmethylphenidate is high in yield, low in cost, environmentally friendly, easy to operate and suitable for industrialization.

The invention discloses preparation methods of methylphenidate and dexmethylphenidate, intermediates and preparation methods of the intermediates. The invention provides the preparation method of the methylphenidate, wherein the preparation method is any one of the following methods: a first method comprises the following steps of in a solvent, carrying out an amino protecting group removal reaction of a compound 4 with an amino de-protection reagent, and thus obtaining the methylphenidate 5; a second method comprises the following steps of under the action of an alkali, carrying out an intramolecular nucleophilic substitution reaction of a compound 11 to obtain the methylphenidate 5; and a third method comprises the following steps of in a closed system, in a solvent, under a palladium on carbon or palladium carbon hydroxide catalytic condition, carrying out a reaction of a compound 9 with hydrogen, to obtain the methylphenidate 5. The synthesis method has the advantages of short steps, cheap and easily obtained raw materials, high product yield, good chiral purity, low production cost, and good atomic economy, and is suitable for industrialized production.

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).

A new and concise route is reported for the first time for the preparation of four stereoisomers of dexmethylphenidate hydrochloride starting from a single reactant, 2-benzyolpyridine, through an eight-step reaction process, which includes hydrogenation,

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.

The invention discloses a preparation method of dexmethylphenidate hydrochloride. The preparation method comprises a step: in a solvent, carrying out salt forming reactions between inorganic acid salts or organic acid salts of compounds represented by the

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.

Novel methods and systems for producing a substantially pure d-threo stereoisomer of methylphenidate or a salt thereof are provided. In particular, methods and systems for producing d-threo-methylphenidate hydrochloride in pure stereoisomeric form from d-

The present invention relates to an improved process for the preparation of Dexmethylphenidate hydrochloride of formula (A). More particularly, the present invention relates to an improved process for the preparation of Dexmethylphenidate hydrochloride of formula (A) and its intermediate d-threo ritalinic acid hydrochloride of formula (III).

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.

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.

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.

A process for preparing the d-threo isomer of methylphenidate hydrochloride which includes (i) resolving a racemic mixture of racemic threo-methylphenidate hydrochloride with a less than stoichiometric amount of tertiary amine base to obtain a methylphenidate-chiral acid salt, (ii) basifying the methylphenidate-chiral acid salt to obtain methylphenidate free base, and (iii) converting the methylphenidate free base into d-threo-methylphenidate hydrochloride.

In the synthesis of (2R,2′R)-threo-(+)-methylphenidate, a ring-closing metathesis approach was adopted to construct the piperidine ring, while Sharpless asymmetric epoxidation was used for the efficient generation of two contiguous stereocenters. Georg Th

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.

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.

The present invention provides a new and efficient process for the preparation of the dexmethylphenidate hydrochloride with high optical purity, the process comprising: (a) reacting a solution of threo-N-Boc-ritalinic acid with (S)-1-phenylethylamine, separating precipitated solid salt of (R,R)-enriched N-Boc-ritalinic acid with (S)-1-phenylethylamnine from the reaction mixture and recrystallizing, reslurring and/or trituring of said salt; (b) mixing the solid salt of (R,R)-N-Boc-ritalinic acid and (S)-1-phenylethylamine obtained in step (a) with aqueous acid and separating (R,R)-N-Boc-ritalinic acid from the mixture; and (c) reacting the (R,R)-N-Boc-ritalinic acid prepared in step (b) with hydrogen chloride and methanol to give dexmethylphenidate hydrochloride with optical purity of at least 99% ee. The present invention further provides salt of (R,R)-N-Boc-ritalinic acid with (S)-1-phenylethylamine as new intermediate in the preparation of dexmethylphenidate hydrochloride.

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.

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

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.

A new method to prepare optically active methylphenidate starting from piperidine is described. The method consists of a transformation of N-methoxycarbonylated piperidine to the corresponding α-methoxylated carbamate utilizing electrochemical oxidation f

Resolution of (±)-threo-methylphenidate (1) with 0.5 M equiv of (R)-(-)-binaphthyl-2,2′-diyl hydrogen phosphate (4) is described. Use of 0.5 M equiv of 4 was found to be better than 1 M equiv for the resolution of (±)-threo-methylphenidate (1) under diffe

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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.

The resolution of (±)-threo-methylphenidate by enzymatic hydrolysis with α-chymotrypsin or subtilisin carlsberg to afford (2S,2'S)-(-)-threo and (2R,2'R)-(+)-threo-methylphenidate hydrochlorides in high enantiomeric purities is described.

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We report the first asymmetric synthesis of the individual enantiomers of methylphenidate (1). From d-pipecolic acid, the (2R,2'R) and (2S,2'R) enantiomers of 1 were obtained in >99% optical purity while the (2S,2'S) and (2R,2'S) enantiomers of 1 were der