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Maguire S, Strachan G, Norvaiša K, Donohoe C, Gomes-da-Silva LC, Senge MO. Porphyrin Atropisomerism as a Molecular Engineering Tool in Medicinal Chemistry, Molecular Recognition, Supramolecular Assembly, and Catalysis. Chemistry 2024; 30:e202401559. [PMID: 38787350 DOI: 10.1002/chem.202401559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Revised: 05/18/2024] [Accepted: 05/24/2024] [Indexed: 05/25/2024]
Abstract
Porphyrin atropisomerism, which arises from restricted σ-bond rotation between the macrocycle and a sufficiently bulky substituent, was identified in 1969 by Gottwald and Ullman in 5,10,15,20-tetrakis(o-hydroxyphenyl)porphyrins. Henceforth, an entirely new field has emerged utilizing this transformative tool. This review strives to explain the consequences of atropisomerism in porphyrins, the methods which have been developed for their separation and analysis and present the diverse array of applications. Porphyrins alone possess intriguing properties and a structure which can be easily decorated and molded for a specific function. Therefore, atropisomerism serves as a transformative tool, making it possible to obtain even a specific molecular shape. Atropisomerism has been thoroughly exploited in catalysis and molecular recognition yet presents both challenges and opportunities in medicinal chemistry.
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Affiliation(s)
- Sophie Maguire
- School of Chemistry, Chair of Organic Chemistry, Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse Street, Dublin, D02R590, Ireland
| | - Grant Strachan
- School of Chemistry, Chair of Organic Chemistry, Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse Street, Dublin, D02R590, Ireland
| | - Karolis Norvaiša
- School of Chemistry, Chair of Organic Chemistry, Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse Street, Dublin, D02R590, Ireland
| | - Claire Donohoe
- School of Chemistry, Chair of Organic Chemistry, Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse Street, Dublin, D02R590, Ireland
- CQC, Coimbra Chemistry Centre, University of Coimbra, Coimbra, 3004-535, Portugal
| | | | - Mathias O Senge
- School of Chemistry, Chair of Organic Chemistry, Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse Street, Dublin, D02R590, Ireland
- Institute for Advanced Study (TUM-IAS), Focus Group-Molecular and Interfacial Engineering of Organic Nanosystems, Technical University of Munich, Lichtenberg Str. 2a, 85748, Garching, Germany
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Jaini R, Lin J, Di L, Sagawa K. PBPK Modeling of PAXLOVID TM: Incorporating Rotamer Conversion Kinetics to Advanced Dissolution and Absorption Model. J Pharm Sci 2024; 113:64-71. [PMID: 37805075 DOI: 10.1016/j.xphs.2023.09.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 09/28/2023] [Accepted: 09/29/2023] [Indexed: 10/09/2023]
Abstract
PAXLOVID™ is a combination medicine of nirmatrelvir tablets co-packaged with ritonavir tablets. Nirmatrelvir is a peptidomimetic inhibitor of SARS-CoV2 main protease (Mpro), developed for the treatment of COVID-19. Ritonavir is co-administered as a pharmacokinetics (PK) enhancer to inhibit CYP3A mediated metabolism increasing exposures of nirmatrelvir. In the solid form, nirmatrelvir exists in a stable single conformational state (ANTI form). However, nirmatrelvir exhibits atropisomerism in solution whereby upon dissolution the ANTI rotational isomer reversibly converts to another conformation state (SYN form). Nirmatrelvir rotamer conversion follows pseudo first order kinetics with a conversion half-life of approximately 15 min in aqueous solutions, which is on a similar time scale of diffusion mediated dissolution from the solid form. In vitro dissolution studies further indicated that rotamer conversion is one of the processes controlling nirmatrelvir dissolution. It was hypothesized that rotamer conversion kinetics would affect oral absorption of nirmatrelvir in vivo. Consequently, a physiologically based pharmacokinetic (PBPK) model for Paxlovid was developed in Simcyp™ using the advanced dissolution, absorption, and metabolism model (ADAM) by incorporating rotamer conversion kinetics to achieve a more mechanistic description of nirmatrelvir oral absorption. The results demonstrate that the established absorption model with rotamer kinetics adequately described observed clinical data from various nirmatrelvir doses, dosage forms, and dosing regimens. The predicted vs. observed AUCinf and Cmax ratios were within 2-fold. The model has been internally used to inform clinical studies and dose recommendations for pediatrics.
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Affiliation(s)
- Rohit Jaini
- Drug Product Design, Pharmaceutical Sciences Small Molecule, Pfizer Inc., Cambridge, MA 02139, United States
| | - Jian Lin
- Pharmacokinetics, Dynamics and Metabolism, Worldwide Research and Development, Pfizer Inc., Groton, CT 06340, United States
| | - Li Di
- Pharmacokinetics, Dynamics and Metabolism, Worldwide Research and Development, Pfizer Inc., Groton, CT 06340, United States
| | - Kazuko Sagawa
- Drug Product Design, Pharmaceutical Sciences Small Molecule, Pfizer Inc., Groton, CT 06340, United States.
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Wang Z, Meng L, Liu X, Zhang L, Yu Z, Wu G. Recent progress toward developing axial chirality bioactive compounds. Eur J Med Chem 2022; 243:114700. [DOI: 10.1016/j.ejmech.2022.114700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 08/15/2022] [Accepted: 08/16/2022] [Indexed: 11/03/2022]
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Abstract
In this paper, theories on anisotropic crystal growth and crystallization of atropisomers are reviewed and a model for anisotropic crystal growth from solution containing slow inter-converting conformers is presented. The model applies to systems with growth-dominated crystallization from solutions and assumes that only one conformation participates in the solute integration step and is present in the crystal lattice. Other conformers, defined as the wrong conformers, must convert to the right conformer before they can assemble to the crystal lattice. The model presents a simple implicit method for evaluating the growth inhibition effect by the wrong conformers. The crystal growth model applies to anisotropic growth in two main directions, namely a slow-growing face and a fast-growing face and requires the knowledge of solute crystal face integration coefficients in both directions. A parameter estimation algorithm was derived to extract those coefficients from data about temporal concentration and crystal size during crystallization and was designed to have a short run time, while providing a high-resolution estimation. The model predicts a size-dependent growth rate and simulations indicated that for a given seed size and solvent system and for an isothermal anti-solvent addition crystallization, the seed loading and the supersaturation at seeding are the main factors impacting the final aspect ratio. The model predicts a decrease of the growth inhibition effect by the wrong conformer with increasing temperature, likely due to faster equilibration between conformers and/or a decrease of the population of the wrong conformer, if of low energy, at elevated temperatures. Finally, the model predicts that solute surface integration becomes the rate-limiting mechanism for high solute integration activation energies, resulting in no impact of the WC on the overall crystal growth process.
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Yang C, Zhou D, Shen Z, Wilson DM, Renner M, Miner JN, Girardet JL, Lee CA. Characterization of Stereoselective Metabolism, Inhibitory Effect on Uric Acid Uptake Transporters, and Pharmacokinetics of Lesinurad Atropisomers. Drug Metab Dispos 2018; 47:104-113. [PMID: 30442650 DOI: 10.1124/dmd.118.080549] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 11/02/2018] [Indexed: 11/22/2022] Open
Abstract
Lesinurad [Zurampic; 2-(5-bromo-4-(4-cyclopropylnaphthalen-1-yl)-4H-1,2,4-triazol-3-ylthio)], a selective inhibitor of uric acid reabsorption transporters approved for the treatment of gout, is a racemate of two atropisomers. The objective of this investigation was to evaluate the stereoselectivity of metabolism, the inhibitory potency on kidney uric acid reabsorption transporters (URAT1 and OAT4), and the clinical pharmacokinetics of the lesinurad atropisomers. Incubations with human liver microsomes (HLM), recombinant CYP2C9, and recombinant CYP3A4 were carried out to characterize the stereoselective formation of three metabolites: M3 (hydroxylation), M4 (a dihydrodiol metabolite), and M6 (S-dealkylation). The formation of M3 in HLM with atropisomer 1 was approximately twice as much as that with atropisomer 2, whereas formation of M4 with atropisomer 1 was 8- to 12-fold greater than that with atropisomer 2. There were no significant differences in the plasma protein binding among lesinurad and the atropisomers. Following oral administration of 400 mg lesinurad once daily for 14 days to healthy human volunteers, the systemic exposure (C max at steady state and area under the concentration-time curve from time zero to the time of dosing interval) of atropisomer 1 was approximately 30% lower than that of atropisomer 2, whereas renal clearance was similar. In vitro cell-based assays using HEK293 stable cells expressing URAT1 and OAT4 demonstrated that atropisomer 2 was approximately 4-fold more potent against URAT1 than atropisomer 1 and equally active against OAT4. In conclusion, lesinurad atropisomers showed stereoselectivity in clinical pharmacokinetics, metabolism, and inhibitory potency against URAT1.
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Affiliation(s)
- Chun Yang
- Preclinical and Clinical DMPK (C.Y., Z.S., C.A.L.), Bioanalytical (D.Z., D.M.W.), Biology (J.N.M.), and Chemistry (M.R., J.-L.G.) Departments, Ardea Biosciences, Inc., San Diego, California
| | - Dongmei Zhou
- Preclinical and Clinical DMPK (C.Y., Z.S., C.A.L.), Bioanalytical (D.Z., D.M.W.), Biology (J.N.M.), and Chemistry (M.R., J.-L.G.) Departments, Ardea Biosciences, Inc., San Diego, California
| | - Zancong Shen
- Preclinical and Clinical DMPK (C.Y., Z.S., C.A.L.), Bioanalytical (D.Z., D.M.W.), Biology (J.N.M.), and Chemistry (M.R., J.-L.G.) Departments, Ardea Biosciences, Inc., San Diego, California
| | - David M Wilson
- Preclinical and Clinical DMPK (C.Y., Z.S., C.A.L.), Bioanalytical (D.Z., D.M.W.), Biology (J.N.M.), and Chemistry (M.R., J.-L.G.) Departments, Ardea Biosciences, Inc., San Diego, California
| | - Matthew Renner
- Preclinical and Clinical DMPK (C.Y., Z.S., C.A.L.), Bioanalytical (D.Z., D.M.W.), Biology (J.N.M.), and Chemistry (M.R., J.-L.G.) Departments, Ardea Biosciences, Inc., San Diego, California
| | - Jeffrey N Miner
- Preclinical and Clinical DMPK (C.Y., Z.S., C.A.L.), Bioanalytical (D.Z., D.M.W.), Biology (J.N.M.), and Chemistry (M.R., J.-L.G.) Departments, Ardea Biosciences, Inc., San Diego, California
| | - Jean-Luc Girardet
- Preclinical and Clinical DMPK (C.Y., Z.S., C.A.L.), Bioanalytical (D.Z., D.M.W.), Biology (J.N.M.), and Chemistry (M.R., J.-L.G.) Departments, Ardea Biosciences, Inc., San Diego, California
| | - Caroline A Lee
- Preclinical and Clinical DMPK (C.Y., Z.S., C.A.L.), Bioanalytical (D.Z., D.M.W.), Biology (J.N.M.), and Chemistry (M.R., J.-L.G.) Departments, Ardea Biosciences, Inc., San Diego, California
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Glunz PW. Recent encounters with atropisomerism in drug discovery. Bioorg Med Chem Lett 2018; 28:53-60. [DOI: 10.1016/j.bmcl.2017.11.050] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 11/29/2017] [Accepted: 11/30/2017] [Indexed: 02/07/2023]
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Elleraas J, Ewanicki J, Johnson TW, Sach NW, Collins MR, Richardson PF. Conformational Studies and Atropisomerism Kinetics of the ALK Clinical Candidate Lorlatinib (PF-06463922) and Desmethyl Congeners. Angew Chem Int Ed Engl 2016; 55:3590-5. [DOI: 10.1002/anie.201509240] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 11/27/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Jeff Elleraas
- Oncology Medicinal Chemistry; Pfizer, La Jolla; 10770 Science Center Drive San Diego CA 92121 USA
| | - Jason Ewanicki
- Oncology Medicinal Chemistry; Pfizer, La Jolla; 10770 Science Center Drive San Diego CA 92121 USA
| | - Ted W. Johnson
- Oncology Medicinal Chemistry; Pfizer, La Jolla; 10770 Science Center Drive San Diego CA 92121 USA
| | - Neal W. Sach
- Oncology Medicinal Chemistry; Pfizer, La Jolla; 10770 Science Center Drive San Diego CA 92121 USA
| | - Michael R. Collins
- Oncology Medicinal Chemistry; Pfizer, La Jolla; 10770 Science Center Drive San Diego CA 92121 USA
| | - Paul F. Richardson
- Oncology Medicinal Chemistry; Pfizer, La Jolla; 10770 Science Center Drive San Diego CA 92121 USA
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Elleraas J, Ewanicki J, Johnson TW, Sach NW, Collins MR, Richardson PF. Conformational Studies and Atropisomerism Kinetics of the ALK Clinical Candidate Lorlatinib (PF-06463922) and Desmethyl Congeners. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201509240] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Jeff Elleraas
- Oncology Medicinal Chemistry; Pfizer, La Jolla; 10770 Science Center Drive San Diego CA 92121 USA
| | - Jason Ewanicki
- Oncology Medicinal Chemistry; Pfizer, La Jolla; 10770 Science Center Drive San Diego CA 92121 USA
| | - Ted W. Johnson
- Oncology Medicinal Chemistry; Pfizer, La Jolla; 10770 Science Center Drive San Diego CA 92121 USA
| | - Neal W. Sach
- Oncology Medicinal Chemistry; Pfizer, La Jolla; 10770 Science Center Drive San Diego CA 92121 USA
| | - Michael R. Collins
- Oncology Medicinal Chemistry; Pfizer, La Jolla; 10770 Science Center Drive San Diego CA 92121 USA
| | - Paul F. Richardson
- Oncology Medicinal Chemistry; Pfizer, La Jolla; 10770 Science Center Drive San Diego CA 92121 USA
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Kazmierski WM, Danehower S, Duan M, Ferris RG, Elitzin V, Minick D, Sharp M, Stewart E, Villeneuve M. Biological and Structural Characterization of Rotamers of C-C Chemokine Receptor Type 5 (CCR5) Inhibitor GSK214096. ACS Med Chem Lett 2014; 5:1296-9. [PMID: 25516787 DOI: 10.1021/ml5004124] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 10/28/2014] [Indexed: 11/28/2022] Open
Abstract
We recently reported the discovery of preclinical CCR5 inhibitor GSK214096, 1 (J. Med. Chem. 2011, 54, 756). Detailed characterization of 1 revealed that it exists as a mixture of four separable atropisomers A-D. The two slow-interconverting pairs of rotamers A + B and C + D were separated and further characterized. HIV and CCR5-mediated chemotaxis data strongly suggest that the antiviral potency of 1 is due to rotamers A + B and not C + D. Furthermore, integrated UV, vibrational circular dichroism VCD and computational approach allowed to determine the M chirality in C + D (and P chirality in A + B). These findings imply additional avenues to be pursued toward new CCR5 antagonists.
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Affiliation(s)
- Wieslaw M. Kazmierski
- Infectious
Diseases TAU and ‡Platform Technology and Science, GlaxoSmithKline, Five Moore Drive, Research Triangle Park, North Carolina 27709-3398, United States
| | - Susan Danehower
- Infectious
Diseases TAU and ‡Platform Technology and Science, GlaxoSmithKline, Five Moore Drive, Research Triangle Park, North Carolina 27709-3398, United States
| | - Maosheng Duan
- Infectious
Diseases TAU and ‡Platform Technology and Science, GlaxoSmithKline, Five Moore Drive, Research Triangle Park, North Carolina 27709-3398, United States
| | - Robert G. Ferris
- Infectious
Diseases TAU and ‡Platform Technology and Science, GlaxoSmithKline, Five Moore Drive, Research Triangle Park, North Carolina 27709-3398, United States
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A review of the effect of multiple conformers on crystallization from solution and strategies for crystallizing slow inter-converting conformers. Chem Eng Sci 2014. [DOI: 10.1016/j.ces.2013.11.025] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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12
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Zask A, Murphy J, Ellestad GA. Biological Stereoselectivity of Atropisomeric Natural Products and Drugs. Chirality 2013; 25:265-74. [DOI: 10.1002/chir.22145] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 10/26/2012] [Indexed: 11/07/2022]
Affiliation(s)
- Arie Zask
- Department of Chemistry; Columbia University; New York New York 10027
| | - John Murphy
- Department of Chemistry; Columbia University; New York New York 10027
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Pivonka DE, Wesolowski SS. Vibrational circular dichroism (VCD) chiral assignment of atropisomers: application to γ-aminobutyric acid (GABA) modulators designed as potential anxiolytic drugs. APPLIED SPECTROSCOPY 2013; 67:365-371. [PMID: 23601535 DOI: 10.1366/12-06934] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Atropisomers exist when axial chirality is present as a result of conformationally restricted rotation around a single bond. The interconversion rate of the individual atropisomers is critical to the assessment of chiral stability of a drug throughout scale-up, development, production, and storage as well as in vivo pharmacokinetics. We describe the application of vibrational circular dichroism spectroscopy coupled with quantum mechanics simulations to assign the absolute axial chirality and measure the racemization half-life of a series of potential anxiolytic drugs that act as γ-aminobutyric acid modulators.
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Affiliation(s)
- Don E Pivonka
- AstraZeneca Pharmaceuticals, 1800 Concord Pike, Wilmington, DE 19803, USA
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Laplante SR, D Fader L, Fandrick KR, Fandrick DR, Hucke O, Kemper R, Miller SPF, Edwards PJ. Assessing atropisomer axial chirality in drug discovery and development. J Med Chem 2011; 54:7005-22. [PMID: 21848318 DOI: 10.1021/jm200584g] [Citation(s) in RCA: 492] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Steven R Laplante
- Department of Chemistry, Boehringer Ingelheim (Canada) Ltd., 2100 Cunard Street, Laval, Quebec, H7S 2G5, Canada.
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LaPlante SR, Edwards PJ, Fader LD, Jakalian A, Hucke O. Revealing Atropisomer Axial Chirality in Drug Discovery. ChemMedChem 2011; 6:505-13. [DOI: 10.1002/cmdc.201000485] [Citation(s) in RCA: 279] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Indexed: 11/09/2022]
Affiliation(s)
- Steven R. LaPlante
- Department of Chemistry, Boehringer Ingelheim (Canada) Ltd., 2100 Cunard Street, Laval, QC, H7S 2G5 (Canada), Fax: (+1) 450‐682‐8434
| | - Paul J. Edwards
- Department of Chemistry, Boehringer Ingelheim (Canada) Ltd., 2100 Cunard Street, Laval, QC, H7S 2G5 (Canada), Fax: (+1) 450‐682‐8434
| | - Lee D. Fader
- Department of Chemistry, Boehringer Ingelheim (Canada) Ltd., 2100 Cunard Street, Laval, QC, H7S 2G5 (Canada), Fax: (+1) 450‐682‐8434
| | - Araz Jakalian
- Department of Chemistry, Boehringer Ingelheim (Canada) Ltd., 2100 Cunard Street, Laval, QC, H7S 2G5 (Canada), Fax: (+1) 450‐682‐8434
| | - Oliver Hucke
- Department of Chemistry, Boehringer Ingelheim (Canada) Ltd., 2100 Cunard Street, Laval, QC, H7S 2G5 (Canada), Fax: (+1) 450‐682‐8434
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Clayden J, Moran W, Edwards P, LaPlante S. The Challenge of Atropisomerism in Drug Discovery. Angew Chem Int Ed Engl 2009; 48:6398-401. [DOI: 10.1002/anie.200901719] [Citation(s) in RCA: 503] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Clayden J, Moran W, Edwards P, LaPlante S. Atropisomerie als Herausforderung in der Medikamentenentwicklung. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200901719] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Tucci FC, Hu T, Mesleh MF, Bokser A, Allsopp E, Gross TD, Guo Z, Zhu YF, Struthers RS, Ling N, Chen C. Atropisomeric property of 1-(2,6-difluorobenzyl)-3-[(2R)-amino-2-phenethyl]-5-(2-fluoro-3-methoxyphenyl)-6-methyluracil. Chirality 2005; 17:559-64. [PMID: 16196024 DOI: 10.1002/chir.20198] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
1-(2,6-Difluorobenzyl)-3-[(2R)-amino-2-phenethyl]-5-(2-fluoro-3-methoxyphenyl)-6-methyluracil (6), a potent and orally active antagonist of the human gonadotropin-releasing hormone receptor, exists as a pair of atropisomers in solution, which was detected by NMR spectroscopy, and separable by HPLC. In addition to a (R)-configured benzylamine, there is a second stereogenic element due to the presence of a chiral axis between the substituted 5-phenyl group and the uracil core. The rate constant of the interconversion (k = 5.07 x 10(-5) s(-1)) of these two atropisomers was determined by proton NMR analysis of a diastereoisomer-enriched sample in aqueous solution at 25 degrees C, and the corresponding Gibbs free energy DeltaG(#) of rotation barrier (97.4 kJ mol(-1)) was calculated using the Eyring equation. The diastereoisomer half-life at physiological temperature (37 degrees C) in aqueous media was estimated to be about 46 min.
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Affiliation(s)
- Fabio C Tucci
- Department of Medicinal Chemistry, Neurocrine Biosciences, Inc., San Diego, CA 92130, USA
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