Approaches to the Preparation of Enantiomerically Pure (2R,2′R)-(+)-threo-Methylphenidate Hydrochloride

Prashad, Mahavir

doi:10.1002/1615-4169(200107)343:5<379::aid-adsc379>3.0.co;2-4

Cited by 28 publications

(14 citation statements)

References 20 publications

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“…52 The mean absolute bioavailability of dl-MPH has been reported to be 30%, but ranges from 11% to 51%. 60,61 In effect, first-pass metabolism biocatalytically "resolves" oral dl-MPH, 62 resulting in only the d-isomer appreciably reaching the bloodstream. The d-isomer component of dl-MPH is generally regarded as the pharmacologically active isomer, responsible for efficacy in the treatment of ADHD.…”

Section: Discussionmentioning

confidence: 99%

Transdermal and Oral dl-Methylphenidate–Ethanol Interactions in C57BL/6J Mice: Transesterification to Ethylphenidate and Elevation of d-Methylphenidate Concentrations

Bell

Novak

Griffin

et al. 2011

Journal of Pharmaceutical Sciences

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We tested the hypothesis that C57BL/6J mice will model human metabolic interactions between dl-methylphenidate (MPH) and ethanol, placing an emphasis on the MPH transdermal system (MTS). Specifically, we asked: (1) will ethanol increase d-MPH biological concentrations, (2) will MTS facilitate the systemic bioavailability of l-MPH, and (3) will l-MPH enantioselectively interact with ethanol to yield l-ethylphenidate (l-EPH)? Mice were dosed with MTS (¼ of a 12.5 cm2 patch on shaved skin) or a comparable oral dl-MPH dose (7.5 mg/kg), with or without ethanol (3.0 g/kg), and then placed in metabolic cages for 3 h. MPH and EPH isomer concentrations in blood, brain, and urine were analyzed by gas chromatographic–mass spectrometry monitoring of N-(S)-prolylpiperidyl fragments. As in humans, MTS greatly facilitated the absorption of l-MPH in this mouse strain. Similarly, ethanol led to the enantioselective formation of l-EPH and to an elevation in d-MPH concentrations with both MTS and oral MPH. Although only guarded comparisons between MTS and oral MPH can be made due to route-dependent drug absorption rate differences, MTS was associated with significant MPH–ethanol interactions. Ethanol-mediated increases in circulating concentrations of d-MPH carry toxicological and abuse liability implications should this animal model hold for ethanol-consuming attention-deficit hyperactivity disorder patients or coabusers.

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Section: Discussionmentioning

confidence: 99%

Transdermal and Oral dl-Methylphenidate–Ethanol Interactions in C57BL/6J Mice: Transesterification to Ethylphenidate and Elevation of d-Methylphenidate Concentrations

Bell

Novak

Griffin

et al. 2011

Journal of Pharmaceutical Sciences

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“…3 The activity of Ritalin ® promotes an enhancement of the cognitive performance in both adults and children diagnosed with AD/HD. 4 Although Ritalin ® is available in the market as the racemate, the (2R,2%R)-(+)-threo-methylphenidate has been reported to be up to 38 times 5 more active than (2S,2%S)-(−)-threo-methylphenidate and several racemic [6][7][8][9] and chiral [10][11][12][13] synthesis of threo-methylphenidate were reported previously.…”

Section: Thementioning

confidence: 99%

“…In this way, a set of available tertiary amines as bases was investigated. In all cases a variable ratio of compounds 2 and 5 was observed ( Table 1, entries [8][9][10][11][12][13][14] and the use of KOt-Bu furnished the compound 5 as a major product (entry 15). Interestingly, the best yield of compound 2 (60%) was achieved when DBU was employed in the absence of a thiophile (Table 1, entry 14) in which thiazolidinone 5 was not isolated.…”

Section: Thementioning

confidence: 99%

A concise and stereoselective synthesis of (+/−)-erythro-methylphenidate

Russowsky

Neto

2003

Tetrahedron Letters

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Abstract-A concise and stereoselective synthesis of racemic erythro-methylphenidate (1) is described. The coupling reaction between piperidine-2-thione (3) and 2-bromo-2-phenylmethylacetate (4) afforded the b-enaminocarbonyl compound 2 in 60% yield by a modified Eschenmoser sulfide contraction reaction. In most cases the bicyclic thiazolidinone 5 was produced. Diastereoselective reduction of 2 in the presence of borohydrydes furnished the (+/−)-erythro-methylphenidate in good yields with dr >95%. © 2003 Elsevier Science Ltd. All rights reserved. The(+/−)-threo-methylphenidate hydrochloride (Ritalin ® ), is an indirect catecholamine agonist, 1 and is the drug treatment of choice for the attention deficit/ hyperactivity disorder (AD/HD), 2 one of the most common behavioral disorders of childhood which affects 5-10% of the general population. 3 The activity of Ritalin ® promotes an enhancement of the cognitive performance in both adults and children diagnosed with AD/HD. 4 Although Ritalin ® is available in the market as the racemate, the (2R,2%R)-(+)-threo-methylphenidate has been reported to be up to 38 times 5 more active than (2S,2%S)-(−)-threo-methylphenidate and several racemic 6-9 and chiral 10-13 synthesis of threo-methylphenidate were reported previously.Although the erythro-methylphenidate exhibits very few therapeutic properties and toxic hypertensive effects, 14 the stereoselective synthesis of the erythro-isomer can be helpful due to the possibility of resolution and epimerization of the erythro-isomer. 2,15 This approach was used early in the original synthesis of (+/−)-threomethylphenidate. Close to this, an enantioselective synthesis of (2S,2%S)-erythro-methylphenidate was recently published by Due to this fact and relating to our interest in the synthesis of b-aminocarbonyl compounds 17,18 we would like to communicate in this paper our approach to the synthesis of (+/−)-erythro-methylphenidate 1 applying a new concise stereoselective synthetic strategy.We envisaged obtaining 1 based on a stereoselective reduction of a b-enaminocarbonyl compound 2 which is readily accessible by the Eschenmoser sulfide contraction reaction 19,20 (Scheme 1).The needed piperidine-2-thione (3) was prepared in 91% yield after reaction of piperidine-2-one with Lawesson reagent. 21 The bromoester 4 was obtained by sterification and subsequent a-bromination 22 of 2-phenylacetic acid in 71% overall yield after purufication by horizontal destilation at reduced pressure. Next, the condensation reaction of compounds 3 and 4 was carried out under the Eschenmoser sulfide contraction reaction Scheme 1. The retrosynthetic analysis of 1 based on the eschemoser sulfide contraction reaction.

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“…[5,6] Originally, it was marketed as a mixture of two racemates, consisting of 80% (±)-erythro and 20% (±)-threo isomers, but successive studies demonstrated that the pharmacologically active diastereomers are associated with the (±)-threo form. [7][8][9][10] Subsequent studies focused on the separation of the two diastereomers and interconversion of (±)-erythro racemate to its (±)-threo counterpart. The (±)-threo racemate exists as two enantiomers, (+)-threo-MPH (2R,2'R) and (-)-threo-MPH (2S,2'S), and the absolute stereochemistry of the most pharmacologically active enantiomer of MPH ((+)-threo) has been characterized [11][12][13] and developed as a medication to treat ADHD in its own right.…”

Section: Introductionmentioning

confidence: 99%

Analytical characterization and pharmacological evaluation of the new psychoactive substance 4‐fluoromethylphenidate (4F‐MPH) and differentiation between the (±)‐threo and (±)‐erythro diastereomers

McLaughlin

Morris

Kavanagh

et al. 2017

Drug Testing and Analysis

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Misuse of (±)-threo-methylphenidate (methyl-2-phenyl-2-(piperidin-2-yl)acetate; Ritalin®, MPH) has long been acknowledged, but the appearance of MPH analogs in the form of ‘research chemicals’ has only emerged in more recent years. 4-Fluoromethylphenidate (4F-MPH) is one of these recent examples and this study presents the identification and analytical characterization of two powdered 4F-MPH products that were obtained from an online vendor in 2015. Interestingly, the products appeared to have originated from two distinct batches given that one product consisted of (±)-threo-4F-MPH isomers whereas the second sample consisted of a mixture of (±)-threo and (±)-erythro 4F-MPH. Monoamine transporter studies using rat brain synaptosomes revealed that the biological activity of the 4F-MPH mixture resided with the (±)-threo- and not the (±)-erythro isomers based on higher potencies determined for blockage of dopamine uptake (IC50 4F-MPHmixture = 66 nM vs. IC50 (±)-threo = 61 nM vs. IC50 (±)-erythro = 8,528 nM) and norepinephrine uptake (IC50 4F-MPHmixture = 45 nM vs. (±)-threo = 31 nM vs. IC50 (±)-erythro = 3,779 nM). In comparison, MPH was three times less potent than (±)-threo-4F-MPH at the dopamine transporter (IC50 = 131 nM) and around 2.5-times less potent at the norepinephrine transporter (IC50 = 83 nM). Both substances were catecholamine selective with IC50 values of 8,805 nM and >10,000 nM for (±)-threo-4F-MPH and MPH at the serotonin transporter. These findings suggest that the psychostimulant properties of (±)-threo-4F-MPH might be more potent in humans than MPH.

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Approaches to the Preparation of Enantiomerically Pure (2R,2′R)-(+)-threo-Methylphenidate Hydrochloride

Cited by 28 publications

References 20 publications

Transdermal and Oral dl-Methylphenidate–Ethanol Interactions in C57BL/6J Mice: Transesterification to Ethylphenidate and Elevation of d-Methylphenidate Concentrations

Transdermal and Oral dl-Methylphenidate–Ethanol Interactions in C57BL/6J Mice: Transesterification to Ethylphenidate and Elevation of d-Methylphenidate Concentrations

A concise and stereoselective synthesis of (+/−)-erythro-methylphenidate

Analytical characterization and pharmacological evaluation of the new psychoactive substance 4‐fluoromethylphenidate (4F‐MPH) and differentiation between the (±)‐threo and (±)‐erythro diastereomers

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