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Dočekal V, Koucký F, Císařová I, Veselý J. Organocatalytic desymmetrization provides access to planar chiral [2.2]paracyclophanes. Nat Commun 2024; 15:3090. [PMID: 38600078 PMCID: PMC11006895 DOI: 10.1038/s41467-024-47407-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 04/01/2024] [Indexed: 04/12/2024] Open
Abstract
Planar chiral [2.2]paracyclophanes consist of two functionalized benzene rings connected by two ethylene bridges. These organic compounds have a wide range of applications in asymmetric synthesis, as both ligands and catalysts, and in materials science, as polymers, energy materials and dyes. However, these molecules can only be accessed by enantiomer separation via (a) time-consuming chiral separations and (b) kinetic resolution approaches, often with a limited substrate scope, yielding both enantiomers. Here, we report a simple, efficient, metal-free protocol for organocatalytic desymmetrization of prochiral diformyl[2.2]paracyclophanes. Our detailed experimental mechanistic study highlights differences in the origin of enantiocontrol of pseudo-para and pseudo-gem diformyl derivatives in NHC catalyzed desymmetrizations based on whether a key Breslow intermediate is irreversibly or reversibly formed in this process. This gram-scale reaction enables a wide range of follow-up derivatizations of carbonyl groups, producing various enantiomerically pure planar chiral [2.2]paracyclophane derivatives, thereby underscoring the potential of this method.
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Affiliation(s)
- Vojtěch Dočekal
- Department of Organic Chemistry, Faculty of Science, Charles University, Hlavova 2030/8, 128 43, Prague, 2, Czech Republic.
| | - Filip Koucký
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030/8, 128 43, Prague, 2, Czech Republic
| | - Ivana Císařová
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030/8, 128 43, Prague, 2, Czech Republic
| | - Jan Veselý
- Department of Organic Chemistry, Faculty of Science, Charles University, Hlavova 2030/8, 128 43, Prague, 2, Czech Republic.
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Koucký F, Dobrovolná T, Kotek J, Císařová I, Havlíčková J, Liška A, Kubíček V, Hermann P. Transition metal complexes of the (2,2,2-trifluoroethyl)phosphinate NOTA analogue as potential contrast agents for 19F magnetic resonance imaging. Dalton Trans 2024. [PMID: 38596878 DOI: 10.1039/d4dt00507d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
A new hexadentate 1,4,7-triazacyclononane-based ligand bearing three coordinating methylene-(2,2,2-trifluoroethyl)phosphinate pendant arms was synthesized and its coordination behaviour towards selected divalent (Mg2+, Ca2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+) and trivalent (Cr3+, Fe3+, Co3+) transition metal ions was studied. The ligand forms stable complexes with late divalent transition metal ions (from Co2+ to Zn2+) and the complexes of these metal ions are formed above pH ∼3. A number of complexes with divalent metal ions were structurally characterized by means of single-crystal X-ray diffraction. The complex of the larger Mn2+ ion adopts a twisted trigonally antiprismatic geometry with a larger coordination cavity and smaller torsion of the pendant arms, whereas the smaller ions Ni2+, Cu2+ and Zn2+ form octahedral species with a smaller cavity and larger pendant arm torsion. In the case of the Co2+ complexes, both coordination arrangements were observed. The complexes with paramagnetic metal ions were studied from the point of view of potential utilization in 19F magnetic resonance imaging. A significant shortening of the 19F NMR longitudinal relaxation times was observed: a sub-millisecond range for complexes of Cr3+, Mn2+ and Fe3+ with symmetric electronic states (t2g3 and HS-d5), the millisecond range for the Ni2+ and Cu2+ complexes and tens of milliseconds for the Co2+ complex. Such short relaxation times are consistent with a short distance between the paramagnetic metal ion and the fluorine atoms (∼5.5-6.5 Å). Among the redox-active complexes (Mn3+/Mn2+, Fe3+/Fe2+, Co3+/Co2+, Cu2+/Cu+), the cobalt complexes show sufficient stability and a paramagnetic-diamagnetic changeover with the redox potential lying in a physiologically relevant range. Thus, the Co3+/Co2+ complex pair can be potentially used as a smart redox-responsive contrast agent for 19F MRI.
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Affiliation(s)
- Filip Koucký
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 42 Prague 2, Czech Republic.
| | - Tereza Dobrovolná
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 42 Prague 2, Czech Republic.
| | - Jan Kotek
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 42 Prague 2, Czech Republic.
| | - Ivana Císařová
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 42 Prague 2, Czech Republic.
| | - Jana Havlíčková
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 42 Prague 2, Czech Republic.
| | - Alan Liška
- Department of Molecular Electrochemistry and Catalysis, J. Heyrovský Institute of Physical Chemistry AS CR, Dolejškova 2155/3, 182 23 Prague 8, Czech Republic
| | - Vojtěch Kubíček
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 42 Prague 2, Czech Republic.
| | - Petr Hermann
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 42 Prague 2, Czech Republic.
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Koucký F, Kotek J, Císařová I, Havlíčková J, Kubíček V, Hermann P. Transition metal complexes of cyclam with two 2,2,2-trifluoroethylphosphinate pendant arms as probes for 19F magnetic resonance imaging. Dalton Trans 2023; 52:12208-12223. [PMID: 37401675 DOI: 10.1039/d3dt01420g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/05/2023]
Abstract
A new cyclam-based ligand bearing two methylene(2,2,2-trifluoroethyl)phosphinate pendant arms was synthesized and its coordination behaviour towards selected divalent transition metal ions [Co(II), Ni(II), Cu(II), Zn(II)] was studied. The ligand was found to be very selective for the Cu(II) ion according to the common Williams-Irving trend. Complexes with all the studied metal ions were structurally characterized. The Cu(II) ion forms two isomeric complexes; the pentacoordinated isomer pc-[Cu(L)] is the kinetic product and the octahedral trans-O,O'-[Cu(L)] isomer is the final (thermodynamic) product of the complexation reaction. Other studied metal ions form octahedral cis-O,O'-[M(L)] complexes. The complexes with paramagnetic metal ions showed a significant shortening of 19F NMR longitudinal relaxation times (T1) to the millisecond range [Ni(II) and Cu(II) complexes] or tens of milliseconds [Co(II) complex] at the temperature and magnetic field relevant for 19F magnetic resonance imaging (MRI). Such a short T1 results from a short distance between the paramagnetic metal ion and the fluorine atoms (∼6.1-6.4 Å). The complexes show high kinetic inertness towards acid-assisted dissociation; in particular, the trans-O,O'-[Cu(L)] complex was found to be extremely inert with a dissociation half-time of 2.8 h in 1 M HCl at 90 °C. Together with the short relaxation time, it potentially enables in vitro/in vivo utilization of the complexes as efficient contrast agents for 19F MRI.
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Affiliation(s)
- Filip Koucký
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 42 Prague 2, Czech Republic.
| | - Jan Kotek
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 42 Prague 2, Czech Republic.
| | - Ivana Císařová
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 42 Prague 2, Czech Republic.
| | - Jana Havlíčková
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 42 Prague 2, Czech Republic.
| | - Vojtěch Kubíček
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 42 Prague 2, Czech Republic.
| | - Petr Hermann
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 42 Prague 2, Czech Republic.
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Kotková Z, Koucký F, Kotek J, Císařová I, Parker D, Hermann P. Copper(II) complexes of cyclams with N-(2,2,2-trifluoroethyl)-aminoalkyl pendant arms as potential probes for 19F magnetic resonance imaging. Dalton Trans 2023; 52:1861-1875. [PMID: 36448539 DOI: 10.1039/d2dt03360g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A series of Cu(II) complexes with cyclam-based ligands containing two N-(2,2,2-trifluoroethyl)-aminoalkyl pendant arms in 1,8-positions (L1: 1,2-ethylene spacer, L2: 1,3-propylene spacer; L3: 1,4-butylene spacer) was studied in respect to potential use as contrast agents for 19F magnetic resonance imaging (MRI). A number of structures of the complexes as well as of several organic precursors were determined by single-crystal X-ray diffraction analysis. Geometric parameters (especially distances between fluorine atoms and the central metal ion) were determined for each complex and the identity of isomeric complex species present in solution was established. The NMR longitudinal relaxation times (T1) of 19F nuclei in the ligands at clinically relevant fields and temperatures (1-2 s) were significantly shortened upon Cu(II) binding to 7-10 ms for [Cu(L1)]2+, 20-30 ms for [Cu(L2)]2+ and 20-50 ms for [Cu(L3)]2+. The trend of the relaxation time shortening is in accordance with the distance and number of chemical bonds between fluorine atoms and the Cu(II) ion. The signals show promising T2*/T1 ratios in the range 0.25-0.55, assuring their good applicability to 19F NMR/MRI. The results show that even the Cu(II) ion, with a small magnetic moment, causes significant relaxation enhancement with a long-range effect and can be considered as a highly suitable metal ion for efficient 19F MRI contrast agents.
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Affiliation(s)
- Zuzana Kotková
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 42 Prague 2, Czech Republic.
| | - Filip Koucký
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 42 Prague 2, Czech Republic.
| | - Jan Kotek
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 42 Prague 2, Czech Republic.
| | - Ivana Císařová
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 42 Prague 2, Czech Republic.
| | - David Parker
- Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Kowloon, Hong Kong
| | - Petr Hermann
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 42 Prague 2, Czech Republic.
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Maďar M, Koláčná L, Koucký F, Havlíčková J, Kuchár J, Kotek J, Kubíček V, Ludvík J, Hermann P. Derivatives of cyclam-1,8-diacetic acid: synthesis and complexes with divalent transition metal ions. J Organomet Chem 2023. [DOI: 10.1016/j.jorganchem.2023.122641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
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Hrdina R, Holovko-Kamoshenkova OM, Císařová I, Koucký F, Machalický O. Annulated carbamates are precursors for the ring contraction of the adamantane framework. RSC Adv 2022; 12:31056-31060. [PMID: 36349043 PMCID: PMC9620499 DOI: 10.1039/d2ra06402b] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 10/24/2022] [Indexed: 11/26/2023] Open
Abstract
We report a protocol for the one-pot two-step synthesis of noradamantane methylene amines. The first step is the triflic acid-promoted decarboxylation of adamantane carbamates, which causes rearrangement of the adamantane framework to form noradamantane iminium salts, which are reduced to amines in the second separate step.
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Affiliation(s)
- Radim Hrdina
- Charles University, Faculty of Science, Department of Organic Chemistry Hlavova 8 12840 Praha Czech Republic
| | - Oksana M Holovko-Kamoshenkova
- Charles University, Faculty of Science, Department of Organic Chemistry Hlavova 8 12840 Praha Czech Republic
- Uzhhorod National University Narodna Ploshcha 3 88000 Uzhhorod Ukraine
| | - Ivana Císařová
- Charles University, Faculty of Science, Department of Inorganic Chemistry Hlavova 8 12840 Praha Czech Republic
| | - Filip Koucký
- Charles University, Faculty of Science, Department of Inorganic Chemistry Hlavova 8 12840 Praha Czech Republic
| | - Oldřich Machalický
- University of Pardubice, Faculty of Chemical Technology Studentská 573 53210 Pardubice Czech Republic
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Herynek V, Martinisková M, Bobrova Y, Gálisová A, Kotek J, Hermann P, Koucký F, Jirák D, Hájek M. Low-molecular-weight paramagnetic 19F contrast agents for fluorine magnetic resonance imaging. MAGMA 2018; 32:115-122. [PMID: 30498883 PMCID: PMC6514088 DOI: 10.1007/s10334-018-0721-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 11/20/2018] [Accepted: 11/21/2018] [Indexed: 12/24/2022]
Abstract
Objective 19F MRI requires biocompatible and non-toxic soluble contrast agents with high fluorine content and with suitable 19F relaxation times. Probes based on a DOTP chelate with 12 magnetically equivalent fluorine atoms (DOTP-tfe) and a lanthanide(III) ion shortening the relaxation times were prepared and tested. Methods Complexes of DOTP-tfe with trivalent paramagnetic Ce, Dy, Ho, Tm, and Yb ions were synthetized and characterized. 19F relaxation times were determined and compared to those of the La complex and of the empty ligand. In vitro and in vivo 19F MRI was performed at 4.7 T. Results 19F relaxation times strongly depended on the chelated lanthanide(III) ion. T1 ranged from 6.5 to 287 ms, T2 from 3.9 to 124.4 ms, and T2* from 1.1 to 3.1 ms. All complexes in combination with optimized sequences provided sufficient signal in vitro under conditions mimicking experiments in vivo (concentrations 1.25 mM, 15-min scanning time). As a proof of concept, two contrast agents were injected into the rat muscle; 19F MRI in vivo confirmed the in vivo applicability of the probe. Conclusion DOTP-based 19F probes showed suitable properties for in vitro and in vivo visualization and biological applications. The lanthanide(III) ions enabled us to shorten the relaxation times and to trim the probes according to the actual needs. Similar to the clinically approved Gd3+ chelates, this customized probe design ensures consistent biochemical properties and similar safety profiles.
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Affiliation(s)
- Vít Herynek
- Center for Advanced Preclinical Imaging, First Faculty of Medicine, Charles University, Salmovská 3, Prague, Czech Republic.
- MR-Unit, Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, Prague, Czech Republic.
| | - Marie Martinisková
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 12843, Prague 2, Czech Republic
| | - Yulia Bobrova
- Department of Low Temperature Physics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Prague, Czech Republic
| | - Andrea Gálisová
- MR-Unit, Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, Prague, Czech Republic
| | - Jan Kotek
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 12843, Prague 2, Czech Republic
| | - Petr Hermann
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 12843, Prague 2, Czech Republic
| | - Filip Koucký
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 12843, Prague 2, Czech Republic
| | - Daniel Jirák
- MR-Unit, Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, Prague, Czech Republic
| | - Milan Hájek
- MR-Unit, Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, Prague, Czech Republic
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