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Markus A, Schreiber JA, Goerges G, Frehland B, Schepmann D, Daniliuc C, Fröhlich R, Seebohm G, Wünsch B. Phenol- benzoxazolone bioisosteres of GluN2B-NMDA receptor antagonists: Unexpected rearrangement during reductive alkylation with phenylcyclohexanone. Arch Pharm (Weinheim) 2022; 355:e2200225. [PMID: 35908158 DOI: 10.1002/ardp.202200225] [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: 04/28/2022] [Revised: 06/23/2022] [Accepted: 07/07/2022] [Indexed: 11/10/2022]
Abstract
Negative allosteric modulators of N-methyl- d-aspartate receptors containing the GluN2B subunit represent promising drug candidates for the treatment of various neurological disorders including stroke, epilepsy, and Parkinson's disease. To increase the bioavailability and GluN2B affinity, the phenol of the potent benzazepine-based inhibitor, WMS-1410 (3), was replaced bioisosterically by a benzoxazolone moiety and the phenylbutyl side chain was conformationally restricted in a phenylcyclohexyl substituent. A four-step, one-pot procedure transformed the oxazolo-benzazepine 7 into the phenylcyclohexyl derivative 11. The same protocol was applied to the methylated analog 12, which unexpectedly led to ring-contracted oxazolo-isoquinolines 18. This rearrangement was explained by the additional methyl moiety in the 8-position inhibiting the formation of the planar intermediate iminium ion with phenylcyclohexanone. The allyl protective group of 11 and 18 was removed with RhCl3 and HCl to obtain the tricyclic compounds 5 and 19 without substituent at the oxazolone ring. The structures of the rearranged products 18 and 19 were elucidated by X-ray crystal structure analysis. The oxazolo-isoquinoline trans-18 with allyl moiety (Ki = 89 nM) and the oxazolo-benzazepine 5 without substituent at the oxazolone ring (Ki = 114 nM) showed GluN2B affinity in the same range as the lead compound 3. In two-electrode voltage clamp measurements, 5 displayed only weak inhibitory activity.
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Affiliation(s)
- Alexander Markus
- Westfälische Wilhelms-Universität Münster, Institut für Pharmazeutische und Medizinische Chemie, Münster, Germany
| | - Julian A Schreiber
- Westfälische Wilhelms-Universität Münster, Institut für Pharmazeutische und Medizinische Chemie, Münster, Germany.,University Hospital Münster, Department of Cardiovascular Medicine, Cellular Electrophysiology and Molecular Biology, Institute for Genetics of Heart Diseases (IfGH), Münster, Germany
| | - Gunnar Goerges
- University Hospital Münster, Department of Cardiovascular Medicine, Cellular Electrophysiology and Molecular Biology, Institute for Genetics of Heart Diseases (IfGH), Münster, Germany
| | - Bastian Frehland
- Westfälische Wilhelms-Universität Münster, Institut für Pharmazeutische und Medizinische Chemie, Münster, Germany
| | - Dirk Schepmann
- Westfälische Wilhelms-Universität Münster, Institut für Pharmazeutische und Medizinische Chemie, Münster, Germany
| | - Constantin Daniliuc
- Westfälische Wilhelms-Universität Münster, Organisch-Chemisches Institut, Münster, 48149, Germany
| | - Roland Fröhlich
- Westfälische Wilhelms-Universität Münster, Organisch-Chemisches Institut, Münster, 48149, Germany
| | - Guiscard Seebohm
- University Hospital Münster, Department of Cardiovascular Medicine, Cellular Electrophysiology and Molecular Biology, Institute for Genetics of Heart Diseases (IfGH), Münster, Germany.,Westfälische Wilhelms-Universität Münster, GRK 2515, Chemical Biology of Ion Channels (Chembion), Münster, Germany
| | - Bernhard Wünsch
- Westfälische Wilhelms-Universität Münster, Institut für Pharmazeutische und Medizinische Chemie, Münster, Germany.,Westfälische Wilhelms-Universität Münster, GRK 2515, Chemical Biology of Ion Channels (Chembion), Münster, Germany
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Markus A, Schepmann D, Wünsch B. Synthesis of oxazolo-annulated 3-benzazepines designed by merging two negative allosteric NMDA receptor modulators. Arch Pharm (Weinheim) 2022; 355:e2200020. [PMID: 35224754 DOI: 10.1002/ardp.202200020] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [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: 01/14/2022] [Revised: 02/07/2022] [Accepted: 02/08/2022] [Indexed: 12/14/2022]
Abstract
To improve the metabolic stability and receptor selectivity of ifenprodil (1), the benzoxazolone moiety of besonprodil (2) and the 3-benzazepone moiety of WMS-1410 (3) were merged to obtain oxazolobenzazepines of type 4. The 5-(hydroxyethyl)benzoxazolone 7 representing the first key intermediate was prepared in four steps starting with the 4-(2-hydroxyethyl)phenol (8). Mitsunobu reaction of primary alcohol 7 with N-sulfonylated glycine esters established the necessary side chain. The intramolecular Friedel-Crafts acylation of acid 12a containing the N-tosyl protective group led upon decarbonylation exclusively to the tricyclic tetrahydroisoquinoline 14. Protection of the amino moiety by the stronger electron-withdrawing triflyl group resulted in the desired 3-benzazepine 15 without the formation of analogous isoquinoline. The triflyl protective group was cleaved off by K2 CO3 -induced elimination of trifluoromethanesulfinate. In a one-pot three-step procedure, various oxazolobenzazepinediones 15 were obtained, which were reduced to afford the desired secondary alcohols 18.
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Affiliation(s)
- Alexander Markus
- Institut für Pharmazeutische und Medizinische Chemie der Universität Münster, Münster, Germany
| | - Dirk Schepmann
- Institut für Pharmazeutische und Medizinische Chemie der Universität Münster, Münster, Germany
| | - Bernhard Wünsch
- Institut für Pharmazeutische und Medizinische Chemie der Universität Münster, Münster, Germany.,GRK 2515, Chemical Biology of Ion Channels (Chembion), Westfälische Wilhelms-Universität Münster, Münster, Germany
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