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Gao D, Penno C, Wünsch B. Rigid Scaffolds: Synthesis of 2,6-Bridged Piperazines with Functional Groups in all three Bridges. ChemistryOpen 2020; 9:874-889. [PMID: 32884883 PMCID: PMC7450790 DOI: 10.1002/open.202000188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/06/2020] [Indexed: 11/10/2022] Open
Abstract
The activity of pharmacologically active compounds can be increased by presenting a drug in a defined conformation, which fits exactly into the binding pocket of its target. Herein, the piperazine scaffold was conformationally restricted by substituted C2- or C3-bridges across the 2- and 6-position. At first, a three-step, one-pot procedure was developed to obtain reproducibly piperazine-2,6-diones with various substituents at the N-atoms in high yields. Three strategies for bridging of piperazine-2,6-diones were pursued: 1. The bicyclic mixed ketals 8-benzyl-6-ethoxy-3-(4-methoxybenzyl)-6-(trimethylsilyloxy)-3,8-diazabicyclo[3.2.1]octane-2,4-diones were prepared by Dieckmann analogous cyclization of 2-(3,5-dioxopiperazin-2-yl)acetates. 2. Stepwise allylation, hydroboration and oxidation of piperazine-2,6-diones led to 3-(3,5-dioxopiperazin-2-yl)propionaldehydes. Whereas reaction of such an aldehyde with base provided the bicyclic alcohol 9-benzyl-6-hydroxy-3-(4-methoxybenzyl)-3,9-diazabicyclo[3.3.1]nonane-2,4-dione in only 10 % yield, the corresponding sulfinylimines reacted with base to give N-(2,4-dioxo-3,9-diazabicyclo[3.3.1]nonan-6-yl)-2-methylpropane-2-sulfinamides in >66 % yield. 3. Transformation of a piperazine-2,6-dione with 1,4-dibromobut-2-ene and 3-halo-2-halomethylprop-1-enes provided 3,8-diazabicyclo[3.2.1]octane-2,4-dione and 3,9-diazabicyclo[3.3.1]nonane-2,4-dione with a vinyl group at the C2- or a methylene group at the C3-bridge, respectively. Since bridging via sulfinylimines and the one-pot bridging with 3-bromo-2-bromomethylprop-1-ene gave promising yields, these strategies will be exploited for the synthesis of novel receptor ligands bearing various substituents in a defined orientation at the carbon bridge.
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Affiliation(s)
- Donglin Gao
- Institut für Pharmazeutische und Medizinische Chemie der WestfälischenWilhelms-Universität MünsterCorrensstraße 4848149MünsterGermany
| | - Christian Penno
- Institut für Pharmazeutische und Medizinische Chemie der WestfälischenWilhelms-Universität MünsterCorrensstraße 4848149MünsterGermany
| | - Bernhard Wünsch
- Institut für Pharmazeutische und Medizinische Chemie der WestfälischenWilhelms-Universität MünsterCorrensstraße 4848149MünsterGermany
- Cells-in-Motion Cluster of Excellence (EXC 1003 – CiM)Westfälische Wilhelms-Universität Münster48149MünsterGermany
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2
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Weber F, Wünsch B. Medicinal Chemistry of σ 1 Receptor Ligands: Pharmacophore Models, Synthesis, Structure Affinity Relationships, and Pharmacological Applications. Handb Exp Pharmacol 2017; 244:51-79. [PMID: 28620761 DOI: 10.1007/164_2017_33] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
In the first part of this chapter, we summarize the various pharmacophore models for σ1 receptor ligands. Common to all of them is a basic amine flanked by two hydrophobic regions, representing the pharmacophoric elements. The development of computer-based models like the 3D homology model is described as well as the first crystal structure of the σ1 receptor. The second part focuses on the synthesis and biological properties of different σ1 receptor ligands, identified as 1-9. Monocyclic piperazines 1 and bicyclic piperazines 2 and 3 were developed as cytotoxic compounds, thus the IC50 values of cell growth and survival inhibition studies are given for all derivatives. The mechanism of cell survival inhibition, induction of time-dependent apoptosis, of compound ent-2a is discussed. Experimentally determined σ1 affinity shows good correlation with the results from molecular dynamics simulations based on a 3D homology model. Spirocyclic compounds 4 and 5 represent well-established σ1 receptor ligands. The homologous fluoroalkyl derivatives 4 have favorable pharmacological properties for use as fluorinated PET tracers. The (S)-configured fluoroethyl substituted compound (S)-4b is under investigation as PET tracer for imaging of σ1 receptors in the brain of patients affected by major depression. 1,3-Dioxanes 6c and 6d display a very potent σ1 antagonist profile and the racemic 1,3-dioxane 6c has high anti-allodynic activity at low doses. The arylpropenylamines 7 are very potent σ1 receptor ligands with high σ1/σ2 selectivity. The top compound 7g acts as an agonist as defined by its ability to potentiate neurite outgrowth at low concentrations. Among the morpholinoethoxypyrazoles 8, 8c (known as S1RA) reveals the most promising pharmacokinetic and physicochemical properties. Due to its good safety profile, 8c is currently being investigated in a phase II clinical trial for the treatment of neuropathic pain. The most potent ligand 9e of 3,4-dihydro-2(1H)-quinolones 9 shows promising anti-nociceptive activity in the formalin test.
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Affiliation(s)
- Frauke Weber
- Institute of Pharmaceutical and Medicinal Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstr. 48, Münster, 48149, Germany.
| | - Bernhard Wünsch
- Institute of Pharmaceutical and Medicinal Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstr. 48, Münster, 48149, Germany
- Cells-in-Motion Cluster of Excellence (EXC 1003 - CIM), University Münster, Münster, Germany
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3
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Weber F, Brune S, Börgel F, Lange C, Korpis K, Bednarski PJ, Laurini E, Fermeglia M, Pricl S, Schepmann D, Wünsch B. Rigidity versus Flexibility: Is This an Issue in σ1 Receptor Ligand Affinity and Activity? J Med Chem 2016; 59:5505-19. [PMID: 27156565 DOI: 10.1021/acs.jmedchem.6b00585] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Stereoisomeric 2,5-diazabicyclo[2.2.2]octanes 14 and 15 were prepared in a chiral-pool synthesis starting from (S)- or (R)-aspartate. The key step in the synthesis was a Dieckmann-analogous cyclization of (dioxopiperazinyl)acetates 8, which involved trapping of the intermediate hemiketal anion with Me3SiCl. The σ1 affinity was tested using membrane preparations from animal (guinea pig) and human origin. The binding of bicyclic compounds was analyzed by molecular dynamics simulations based on a 3D homology model of the σ1 receptor. The good correlation between Ki values observed in the σ1 assays and calculated free binding energy, coupled with the identification of four crucial ligand/receptor interactions, allowed the formulation of structure-affinity relationships. In an in vitro antitumor assay with seven human tumor cell lines, the bicyclic compounds inhibited selectively the growth of the cell line A427, which is due to induction of apoptosis. In this assay, the compounds behave like the known σ1 receptor antagonist haloperidol.
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Affiliation(s)
- Frauke Weber
- Institute of Pharmaceutical and Medicinal Chemistry, University of Münster , Corrensstraße 48, D-48149 Münster, Germany
| | - Stefanie Brune
- Institute of Pharmaceutical and Medicinal Chemistry, University of Münster , Corrensstraße 48, D-48149 Münster, Germany
| | - Frederik Börgel
- Institute of Pharmaceutical and Medicinal Chemistry, University of Münster , Corrensstraße 48, D-48149 Münster, Germany
| | - Carsten Lange
- Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Greifswald , Friedrich-Ludwig-Jahn-Straße 17, 17487 Greifswald, Germany
| | - Katharina Korpis
- Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Greifswald , Friedrich-Ludwig-Jahn-Straße 17, 17487 Greifswald, Germany
| | - Patrick J Bednarski
- Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Greifswald , Friedrich-Ludwig-Jahn-Straße 17, 17487 Greifswald, Germany
| | - Erik Laurini
- Molecular Simulations Engineering (MOSE) Laboratory, Department of Engineering and Architecture (DEA), University of Trieste , Via Valerio 6, 34127 Trieste, Italy
| | - Maurizio Fermeglia
- Molecular Simulations Engineering (MOSE) Laboratory, Department of Engineering and Architecture (DEA), University of Trieste , Via Valerio 6, 34127 Trieste, Italy
| | - Sabrina Pricl
- Molecular Simulations Engineering (MOSE) Laboratory, Department of Engineering and Architecture (DEA), University of Trieste , Via Valerio 6, 34127 Trieste, Italy.,National Interuniversity Consortium for Material Science and Technology (INSTM), Research Unit MOSE-DEA, University of Trieste , Via Valerio 6, 32127 Trieste, Italy
| | - Dirk Schepmann
- Institute of Pharmaceutical and Medicinal Chemistry, University of Münster , Corrensstraße 48, D-48149 Münster, Germany
| | - Bernhard Wünsch
- Institute of Pharmaceutical and Medicinal Chemistry, University of Münster , Corrensstraße 48, D-48149 Münster, Germany.,Cells-in-Motion Cluster of Excellence (EXC 1003-CiM), University of Münster, 48149 Münster, Germany
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4
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Weber F, Brune S, Korpis K, Bednarski PJ, Laurini E, Dal Col V, Pricl S, Schepmann D, Wünsch B. Synthesis, Pharmacological Evaluation, and σ1 Receptor Interaction Analysis of Hydroxyethyl Substituted Piperazines. J Med Chem 2014; 57:2884-94. [DOI: 10.1021/jm401707t] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Frauke Weber
- Institute
of Pharmaceutical and Medicinal Chemistry, University of Münster, Corrensstraße 48, D-48149 Münster, Germany
| | - Stefanie Brune
- Institute
of Pharmaceutical and Medicinal Chemistry, University of Münster, Corrensstraße 48, D-48149 Münster, Germany
| | - Katharina Korpis
- Institute
of Pharmacy, Department of Pharmaceutical and Medicinal Chemistry, University of Greifswald, F.-L.-Jahn-Straße 17, 17487 Greifswald, Germany
| | - Patrick J. Bednarski
- Institute
of Pharmacy, Department of Pharmaceutical and Medicinal Chemistry, University of Greifswald, F.-L.-Jahn-Straße 17, 17487 Greifswald, Germany
| | - Erik Laurini
- Molecular
Simulations Engineering (MOSE) Laboratory, Department of Engineering
and Architecture (DEA), University of Trieste, Via Valerio 6, 34127 Trieste, Italy
| | - Valentina Dal Col
- Molecular
Simulations Engineering (MOSE) Laboratory, Department of Engineering
and Architecture (DEA), University of Trieste, Via Valerio 6, 34127 Trieste, Italy
| | - Sabrina Pricl
- Molecular
Simulations Engineering (MOSE) Laboratory, Department of Engineering
and Architecture (DEA), University of Trieste, Via Valerio 6, 34127 Trieste, Italy
- National
Interuniversity Consortium for Material Science and Technology (INSTM),
Research Unit MOSE-DEA, University of Trieste, Via Valerio 6, 32127 Trieste, Italy
| | - Dirk Schepmann
- Institute
of Pharmaceutical and Medicinal Chemistry, University of Münster, Corrensstraße 48, D-48149 Münster, Germany
| | - Bernhard Wünsch
- Institute
of Pharmaceutical and Medicinal Chemistry, University of Münster, Corrensstraße 48, D-48149 Münster, Germany
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Borthwick AD. 2,5-Diketopiperazines: synthesis, reactions, medicinal chemistry, and bioactive natural products. Chem Rev 2012; 112:3641-716. [PMID: 22575049 DOI: 10.1021/cr200398y] [Citation(s) in RCA: 611] [Impact Index Per Article: 50.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Holl R, Schepmann D, Wünsch B. Homologous piperazine-alcanols: chiral pool synthesis and pharmacological evaluation. MEDCHEMCOMM 2012. [DOI: 10.1039/c2md20070h] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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7
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Alen J, Dobrzańska L, Van Meervelt L, De Borggraeve WM. 2-(4-Meth-oxy-benz-yl)-4,6-diphenyl-2,5-diaza-bicyclo-[2.2.2]oct-5-en-3-one. Acta Crystallogr Sect E Struct Rep Online 2011; 67:o1070-1. [PMID: 21754395 PMCID: PMC3089292 DOI: 10.1107/s1600536811012165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Accepted: 03/31/2011] [Indexed: 11/14/2022]
Abstract
In the crystal structure of the title compound, C26H24N2O2, weak intermolecular C—H⋯π interactions involving the benzene of the p-methoxy benzyl group and one of the phenyl rings result in the formation of chains consisting of alternating enantiomers. Weak C—H ⋯O interactions with the methoxy O atom lead to the formation of layers, which are interlinked by further C—H⋯O interactions into a three-dimensional assembly.
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Sunnam SK, Schepmann D, Rack E, Fröhlich R, Korpis K, Bednarski PJ, Wünsch B. Synthesis and biological evaluation of conformationally restricted σ(1) receptor ligands with 7,9-diazabicyclo[4.2.2]decane scaffold. Org Biomol Chem 2010; 8:5525-40. [PMID: 20953473 DOI: 10.1039/c0ob00402b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The key step in the synthesis of the 7,9-diazabicyclo[4.2.2]decane system was a modified Dieckmann condensation of piperazinebutyrate 11, which makes use of trapping the first cyclized intermediate with TMS-Cl. Reduction of the bicyclic ketone 14 with LiBH(4) at -90 °C provided diastereoselectively (>99 : 1) the syn-configured alcohol 15a, which was converted into the final alcohol and ethers 16a-g. The configuration at the 2-position was established by X-ray structure analysis of methyl and ethyl ethers 15b and 15c. In contrast to bicyclic systems with a three-carbon bridge, inversion of the configuration at the 2-position of the alcohol 15a failed to give the inverted alcohol 19a. However, an unselective reduction of the ketone 24 with L-Selectride led to the diastereomeric alcohols 16a and 25a in the ratio 36 : 64. LiAlH(4) reduction of the tosylate 20 and the alkene 18 yielded the diazabicyclo-decane 26 and -decene 27 without further substituents at the four-carbon bridge. The σ(1) and σ(2) receptor affinities were investigated in receptor binding studies with radioligands. All test compounds showed a lower σ(1) affinity than the corresponding bicyclic derivatives with a three-membered bridge. The reduced σ(1) receptor affinity is attributed to the larger four-membered bridge. This hypothesis is supported by the alkene 27, which represents the most potent σ(1) ligand of this series (K(i) = 7.5 nM). In the alkene 27 the size and flexibility of the bridge is considerably reduced by the double bond. The methyl ether 25b and the unsubstituted derivatives 26 and 27 revealed moderate inhibition of the growth of the human tumor cell lines A-427, 5637 and MCF-7. Again, these compounds are less potent than the analogues with a three-membered bridge. The IC(50)-value of the most potent σ(1) ligand 27 against the small cell lung cancer cell line A-427 (IC(50) = 10 μM) should be emphasized, since this cell line is particularly sensitive to homologues with a three-carbon bridge.
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Affiliation(s)
- Sunil K Sunnam
- Institut für Pharmazeutische und Medizinische Chemie der Universität Münster, Hittorfstraße 58-62, D-48149, Münster, Germany
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9
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Sunnam SK, Schepmann D, Wibbeling B, Wünsch B. Bicyclic sigma receptor ligands by stereoselective Dieckmann analogous cyclization of piperazinebutyrate. Org Biomol Chem 2010; 8:3715-22. [PMID: 20556273 DOI: 10.1039/c003878d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Starting from racemic 2-aminoadipic acid (6) the piperazinedione 10 with a butyrate side chain was synthesized in four reaction steps. The four-carbon bridge was established upon deprotonation of 10 with LHMDS and subsequent trapping of the lithium alcoholate with Me(3)SiCl to give diastereoselectively the mixed methyl silyl ketal 12 in 94% yield. The relative configuration of the new center of chirality was determined by X-ray crystal structure analysis of 12. The high diastereoselectivity during the conversion of the butyrate 10 into the mixed methyl silyl ketal 12 supports the formation of the lithium alcoholate 11 as central intermediate. Stereoselective reduction of the ketone 13 with LiBH(4) led to the alcohol 14, which was benzylated and reduced to provide the final bicyclic products 16 and 17. Whereas the alcohol 16 shows only moderate affinity to both sigma receptor subtypes, the benzyl ether 17 represents a potent and selective sigma(1) receptor ligand (K(i) = 47 nM). Comparison of the sigma receptor affinities of 16 and 17 with the smaller homologues 5a and 5c clearly indicates that the size of the bridge and the O-substituent determines subtype selectivity.
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Affiliation(s)
- Sunil Kumar Sunnam
- Institut für Pharmazeutische und Medizinische Chemie der Universität Münster, Hittorfstrasse 58-62, D-48149 Münster, Germany
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