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Dive into the research topics where D. Koharski is active.

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Featured researches published by D. Koharski.


Journal of Labelled Compounds and Radiopharmaceuticals | 2014

Synthesis of [3H], [13C3, 15N], and [14C]SCH 900567: an inhibitor of TNF-α (tumor necrosis factor alpha) converting enzyme (TACE)

Sumei Ren; David Hesk; Paul McNamara; D. Koharski; S. Borges

SCH 900567 is a specific inhibitor of tumor necrosis factor-alpha converting enzyme and is a potential candidate for the treatment of rheumatoid arthritis. [(3) H]SCH 900567 was synthesized to support the initial drug metabolism and pharmacokinetics studies. Stable isotope-labeled [(13) C3 , (15) N]SCH 900567 was requested by the bioanalytical group as an internal standard for Liquid chromatography-tandem mass spectrometry (LC-MS/MS) method development as well as by the drug metabolism and pharmacokinetics group for a potential microdose study. [(13) C3 , (15) N]SCH 900567 is synthesized via a linear sequence of seven steps from commercially available materials in 2.6% overall yield. [(14) C]SCH 900567 was needed for a quantitative whole body autoradiography studies and was prepared from unlabeled Active Pharmaceutical Ingredient (API) via hydrolysis of the hydantoin moiety followed by rebuilding the hydantoin ring using potassium [(14) C]cyanate to give the desired product in 42.8% overall yield. Activation of the hydantoin moiety of SCH 900567 to achieve hydrolysis followed by derivatization of the resulting amino acid to avoid decarboxylation during cyclization is also discussed.


Journal of Labelled Compounds and Radiopharmaceuticals | 2016

Synthesis of 3H, 2H4 and 14C-SCH 417690 (Vicriviroc)

David Hesk; S. Borges; S. Hendershot; D. Koharski; Paul S. McNamara; Sumei Ren; S. Saluja; V. Truong; K. Voronin

Vicriviroc or SCH 417690 is a potent and selective antagonist of the CCR5 receptor. CCR5 receptor antagonists have the potential for the treatment of HIV infections. Four distinct isotopically labelled forms of SCH 417690 were synthesized. Low specific activity [(3) H]SCH 417690 was prepared for a preliminary absorption, distribution, metabolism and excretion evaluation of the compound and [(14) C]SCH 417690 for more definitive absorption, distribution, metabolism and excretion work, including an absorption, metabolism and excretion study in man. In addition, high specific activity [(3) H]SCH 417690 was prepared for CCR5 receptor binding work and [(2) H4 ]SCH 417690 was prepared as an internal standard for a liquid chromatography-mass spectrometry bioanalytical method. The paper discusses the synthesis of four isotopically labelled forms of SCH 417690.


Journal of Labelled Compounds and Radiopharmaceuticals | 2015

Synthesis of 3H, 13C,2H3,15N and 14C-labelled SCH 466036, a histamine 3 receptor antagonist.

David Hesk; S. Borges; R. Dumpit; S. Hendershot; D. Koharski; Carolee Lavey; Paul McNamara; K. Voronin

The synthesis of [(3)H]SCH 466036, [Me-(3)H3]SCH 466036, [(13)C,(2)H3,(15)N]SCH 466036 and [(14)C]SCH 466036 is described. [(3)H]SCH 466036 was prepared in two steps via Raney Ni-catalysed exchange with tritiated water. [Me-(3)H3]SCH 466036 was prepared in a single step from [(3)H]methyl iodide in 45% yield. [(13)C,(2)H3,(15)N]SCH 466036 was prepared in two steps from [(15)N]hydroxylamine and [(13)C,(2)H3]methyl iodide with an overall yield of 16%. [(14)C]SCH 466036 was prepared in seven steps from [(14)C]potassium cyanide in an overall yield of 13%.


Journal of Labelled Compounds and Radiopharmaceuticals | 2013

Syntheses of 3H‐labeled, 14C‐labeled, and 2H4‐labeled SCH 444877, phosphodiesterase type 5 inhibitors

Sumei Ren; David Hesk; Paul McNamara; D. Koharski; Sharon Hendershot

The syntheses of [(3) H]SCH 444877, [(2) H4 ]SCH 444877, and [(14) C]SCH 444877 are described. [(3) H]SCH 444877 was prepared in three steps from tritium gas. [(2) H4 ]SCH 444877 was synthesized from [(2) H4 ]ethanolamine in four steps with an overall yield of 40%. [(14) C]SCH 444877 was prepared from barium [(14) C]cyanamide in 10 steps with an overall yield of 8.1%.


Journal of Labelled Compounds and Radiopharmaceuticals | 2018

Synthesis of 3H, 13C2, 2H4 14C-SCH 430765 and 35S-SCH 500946, potent and selective inhibitors of the NPY5 receptor

D. Hesk; D. Koharski; Paul McNamara; Pernilla Royster; S. Saluja; V. Truong; K. Voronin

SCH 430765 and SCH 500496 are potent and selective antagonists of the NPY5 receptor. NPY5 receptor antagonists have the potential for the treatment of obesity. [35 S]SCH 500946 was prepared for a competition binding assay which led to the identification of SCH 430765. Three distinct isotopically labelled forms of SCH 430765 were synthesized. [3 H]SCH 430765 was prepared for a preliminary absorption, distribution, metabolism and excretion data evaluation of the compound and [14 C]SCH 430765 for more definitive absorption, distribution, metabolism and excretion data work. In addition, [13 C2 ,2 H4 ]SCH 430765 was prepared as an internal standard for a LC-MS bioanalytical method. The paper discusses the synthesis of 3 isotopically labelled forms of SCH 430765 and [35 S]SCH 500946.


Journal of Labelled Compounds and Radiopharmaceuticals | 2017

SYNTHESIS OF (3) H, (2) H4 AND (14) C-MK 3814 (Preladenant).

D. Hesk; S. Borges; R. Dumpit; S. Hendershot; D. Koharski; Paul McNamara; Sumei Ren; S. Saluja; Truong; K. Voronin

MK 3814 is a potent and selective antagonist of the A2a receptor. A2a receptor antagonists have the potential for the treatment of Parkinson disease. Three distinct isotopically labelled forms of MK 3814 were synthesized. [3 H]MK 3814 was prepared for a preliminary absorption, distribution, metabolism, and excretion data (ADME) evaluation of the compound and [14 C]MK 3814 for more definitive ADME work, including an absorption, metabolism, and excretion study in man. In addition, [2 H4 ]MK 3814 was prepared as an internal standard for a liquid chromatography mass spectrometry bioanalytical method. This paper discusses the synthesis of 3 isotopically labelled forms of MK 3814.


Journal of Labelled Compounds and Radiopharmaceuticals | 2017

SYNTHESIS OF 3H, 2H4 AND 14C‐MK 3814 (Preladenant)

David Hesk; S. Borges; R. Dumpit; S. Hendershot; D. Koharski; Paul S. McNamara; Sumei Ren; S. Saluja; V. Truong; K. Voronin

MK 3814 is a potent and selective antagonist of the A2a receptor. A2a receptor antagonists have the potential for the treatment of Parkinson disease. Three distinct isotopically labelled forms of MK 3814 were synthesized. [3 H]MK 3814 was prepared for a preliminary absorption, distribution, metabolism, and excretion data (ADME) evaluation of the compound and [14 C]MK 3814 for more definitive ADME work, including an absorption, metabolism, and excretion study in man. In addition, [2 H4 ]MK 3814 was prepared as an internal standard for a liquid chromatography mass spectrometry bioanalytical method. This paper discusses the synthesis of 3 isotopically labelled forms of MK 3814.


Journal of Labelled Compounds and Radiopharmaceuticals | 2017

Synthesis of3H,2H4, and14C-MK 3814 (preladenant)

D. Hesk; S. Borges; R. Dumpit; S. Hendershot; D. Koharski; Paul McNamara; Sumei Ren; S. Saluja; V. Truong; K. Voronin

MK 3814 is a potent and selective antagonist of the A2a receptor. A2a receptor antagonists have the potential for the treatment of Parkinson disease. Three distinct isotopically labelled forms of MK 3814 were synthesized. [3 H]MK 3814 was prepared for a preliminary absorption, distribution, metabolism, and excretion data (ADME) evaluation of the compound and [14 C]MK 3814 for more definitive ADME work, including an absorption, metabolism, and excretion study in man. In addition, [2 H4 ]MK 3814 was prepared as an internal standard for a liquid chromatography mass spectrometry bioanalytical method. This paper discusses the synthesis of 3 isotopically labelled forms of MK 3814.


Journal of Labelled Compounds and Radiopharmaceuticals | 2016

Synthesis of (3) H, (2) H4 and (14) C-SCH 417690 (Vicriviroc).

D. Hesk; S. Borges; S. Hendershot; D. Koharski; Paul McNamara; Sumei Ren; S. Saluja; Truong; K. Voronin

Vicriviroc or SCH 417690 is a potent and selective antagonist of the CCR5 receptor. CCR5 receptor antagonists have the potential for the treatment of HIV infections. Four distinct isotopically labelled forms of SCH 417690 were synthesized. Low specific activity [(3) H]SCH 417690 was prepared for a preliminary absorption, distribution, metabolism and excretion evaluation of the compound and [(14) C]SCH 417690 for more definitive absorption, distribution, metabolism and excretion work, including an absorption, metabolism and excretion study in man. In addition, high specific activity [(3) H]SCH 417690 was prepared for CCR5 receptor binding work and [(2) H4 ]SCH 417690 was prepared as an internal standard for a liquid chromatography-mass spectrometry bioanalytical method. The paper discusses the synthesis of four isotopically labelled forms of SCH 417690.


Journal of Labelled Compounds and Radiopharmaceuticals | 2016

Synthesis of3H,2H4and14C-SCH 417690 (Vicriviroc): 3H,2H4and14C-SCH 417690

D. Hesk; S. Borges; S. Hendershot; D. Koharski; Paul McNamara; Sumei Ren; S. Saluja; V. Truong; K. Voronin

Vicriviroc or SCH 417690 is a potent and selective antagonist of the CCR5 receptor. CCR5 receptor antagonists have the potential for the treatment of HIV infections. Four distinct isotopically labelled forms of SCH 417690 were synthesized. Low specific activity [(3) H]SCH 417690 was prepared for a preliminary absorption, distribution, metabolism and excretion evaluation of the compound and [(14) C]SCH 417690 for more definitive absorption, distribution, metabolism and excretion work, including an absorption, metabolism and excretion study in man. In addition, high specific activity [(3) H]SCH 417690 was prepared for CCR5 receptor binding work and [(2) H4 ]SCH 417690 was prepared as an internal standard for a liquid chromatography-mass spectrometry bioanalytical method. The paper discusses the synthesis of four isotopically labelled forms of SCH 417690.

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