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Martin SF. Bridging Known and Unknown Unknowns: From Natural Products and Their Mimics to Unmet Needs in Neuroscience. Acc Chem Res 2022; 55:2397-2408. [PMID: 35960884 DOI: 10.1021/acs.accounts.1c00773] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Scientific excursions into the unknown are often characterized by unanticipated twists and turns that may lead in directions that never could have been predicted. Decisions made during the course of these explorations determine what we discover. This Account chronicles one such journey that began with a challenge encountered during the synthesis of a natural product and then unfolded over more than 30 years to focus on unmet needs in neuroscience. Specifically, while developing a concise approach to tetrahydroalstonine, a heteroyohimboid alkaloid having α-adrenergic activity, we faced the predicament of assembling a key intermediate. Solving this problem resulted in the serendipitous discovery of the vinylogous Mannich reaction and a productive program wherein we used this powerful construction as a key step in the syntheses of numerous alkaloids. However, we also realized that lessons learned from the synthesis of tetrahydroalstonine could be generalized to invent a new strategy for preparing diverse collections of substituted nitrogen heterocycles that could be screened against biological targets. The approach featured the combination of several reactants in a multicomponent assembly process to give a functionalized intermediate that could be elaborated by various ring-forming reactions to give heterocyclic scaffolds that could be further diversified. Screening these compound sets against a broad range of biological targets revealed some intriguing hits, but none of them led to a productive collaboration in translational research. Notwithstanding this setback, we screened curated members of our collections against proteins in the central nervous system and discovered some substituted B-norbenzomorphans that were selective for the enigmatic sigma-2 receptor (σ2R), an understudied protein that had been primarily associated with cancer. With scant knowledge of its role in neuroscience, we posited that small molecules that bind to σ2R might be neuroprotective, thus launching a new venture. In parallel investigations we prepared analogues of the initial hits, explored their effects in animal models of neurodegenerative and neurological conditions, and identified σ2R as transmembrane protein 97 (TMEM97). After first establishing the neuroprotective effects of several σ2R/TMEM97 ligands in a transgenic Caenorhabditis elegans model of neurodegeneration, we showed that one of these has procognitive effects and reduces levels of proinflammatory cytokines in a transgenic mouse model of Alzheimer's disease. We then identified a closely related σ2R/TMEM97 ligand that mitigates hippocampal-dependent memory deficits, prevents axon degeneration, and protects neurons and oligodendrocytes after traumatic brain injury. In a recent study, this compound was shown to protect retinal ganglion cells from retinal ischemia/reperfusion injury. In other collaborative investigations, we have shown that related, but structurally distinct, σ2R/TMEM97 ligands alleviate neuropathic pain, while a σ2R/TMEM97 ligand representing yet another chemotype reduces impairments associated with alcohol withdrawal. More recently, we have shown that σ2R/TMEM97 ligands enhance survival of cortical neurons in a neuronal model of Huntington's disease. Translational and mechanistic studies in these and other areas are in progress. Solving a problem we faced in natural product synthesis thus served as an unexpected gateway to discoveries that could lead to entirely new approaches to treat neurodegenerative and neurological conditions by targeting σ2R/TMEM97, a protein that has never been associated with these afflictions.
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Affiliation(s)
- Stephen F Martin
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
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Das S, Goswami G, Halder S, Ghorai MK. Domino imino-aldol-aza-Michael and imino-aldol-aza-Michael-imino-aldol reactions: Diastereoselective synthesis of highly functionalized 2,6-disubstituted piperidines. Tetrahedron 2021. [DOI: 10.1016/j.tet.2021.132285] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Al-Tel TH, Srinivasulu V, Al-Marzooq F, Hamad M, Khanfar MA, Ramanathan M, Soares NC. Sequencing Groebke–Blackburn–Bienaymé and Aza-Michael Addition Reactions: A Modular Strategy for Accessing a Diverse Collection of Constrained Benzoxazepine and Imidazopyrazine Systems. SYNTHESIS-STUTTGART 2021. [DOI: 10.1055/s-0040-1706006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
AbstractWe present a divergent strategy that permits access to diversely functionalized benzoxazepinium scaffolds fused to various heterocycles. The described strategy features a one-pot combination of the Groebke–Blackburn–Bienaymé reaction and an aza-Michael addition. Methyl (E)-4-(2-formylphenoxy)but-2-enoate and its derivatives are utilized as central elements in this cascade. These building blocks are reacted with a variety of functionalized amino-azines and tert-butyl isocyanide under ytterbium triflate [Yb(OTf)3] catalysis. The ensuing cascade represents a rapid, modular and atom-economic process that leads to the construction of a diverse collection of constrained benzoxazepinium systems from a wide substrate scope.
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Affiliation(s)
- Taleb H. Al-Tel
- Sharjah Institute for Medical Research, University of Sharjah
- College of Pharmacy, University of Sharjah
| | | | - Farah Al-Marzooq
- Department of Medical Microbiology and Immunology, College of Medicine and Health Sciences, UAE University
| | - Mohamad Hamad
- Sharjah Institute for Medical Research, University of Sharjah
- College of Health Sciences, University of Sharjah
| | - Monther A. Khanfar
- Sharjah Institute for Medical Research, University of Sharjah
- Department of Chemistry, University of Jordan
| | - Mani Ramanathan
- Department of Biology, Chemistry and Environmental Sciences, American University of Sharjah, 26666
| | - Nelson C. Soares
- Sharjah Institute for Medical Research, University of Sharjah
- College of Pharmacy, University of Sharjah
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Abeykoon GA, Sahn JJ, Martin SF. Novel substituted triazolo benzodiazepine scaffolds to explore chemical space. Tetrahedron Lett 2021. [DOI: 10.1016/j.tetlet.2021.152828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Badarau E, Reddy KHV, Loudet A, Simon C, Trembleau L, Claerhout S, Pair E, Massip S, Breton P, Lesur B, Goldstein S, Fourquez JM, Henlin JM, Ghosez L. Productive Syntheses of Privileged Scaffolds Inspired by the Recognition of a Diels-Alder Pattern Common to Three Classes of Natural Products. Chemistry 2020; 26:15477-15481. [PMID: 32428343 DOI: 10.1002/chem.202002372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Indexed: 11/10/2022]
Abstract
Identification of a common Diels-Alder pattern in three classes of bioactive natural products led us to study the synthesis and cycloaddition of a new class of cyclic dienes readily available from β,γ-unsaturated lactams. A practical and readily scalable route to the parent p-methoxybenzyl-protected 6- and 7-membered β,γ-unsaturated lactams was developed. These were readily transformed into the corresponding O-silylated dienes, which were reacted with dimethyl and diethyl fumarate to yield stereoselectively highly functionalized bicyclic adducts. These exhibited unexpected and versatile transformations upon acid hydrolysis depending on the nature of the dienophile substituents and the acid catalyst. All reactions have been performed on multigram quantities. These transformations provide a convenient, economical, and easily scalable pathway for the rapid construction of functionally and stereochemically dense privileged scaffolds for the construction of libraries of natural products-inspired molecules of pharmacological relevance.
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Affiliation(s)
- Eduard Badarau
- IECB, CNRS UMR 5248, Université de Bordeaux, CBMN, 2, rue Robert Escarpit, 33607, Pessac, France.,Bordeaux INP, CNRS UMR 5248, Université de Bordeaux, CBMN, Allée Geoffroy Saint Hilaire, Bat B14, 33600, Pessac, France
| | - K Harsha Vardhan Reddy
- IECB, CNRS UMR 5248, Université de Bordeaux, CBMN, 2, rue Robert Escarpit, 33607, Pessac, France
| | - Aurore Loudet
- IECB, CNRS UMR 5248, Université de Bordeaux, CBMN, 2, rue Robert Escarpit, 33607, Pessac, France
| | - Charles Simon
- IECB, CNRS UMR 5248, Université de Bordeaux, CBMN, 2, rue Robert Escarpit, 33607, Pessac, France
| | - Laurent Trembleau
- UCLouvain, Place Louis Pasteur 1, 1348, Louvain-la-Neuve, Belgium.,Chemistry, G95, School of Natural and Computing Sciences, University of Aberdeen, Meston Walk, Aberdeen, AB24 3UE, UK
| | - Stijn Claerhout
- IECB, CNRS UMR 5248, Université de Bordeaux, CBMN, 2, rue Robert Escarpit, 33607, Pessac, France
| | - Etienne Pair
- IECB, CNRS UMR 5248, Université de Bordeaux, CBMN, 2, rue Robert Escarpit, 33607, Pessac, France
| | - Stéphane Massip
- IECB, CNRS UMR 5248, Université de Bordeaux, CBMN, 2, rue Robert Escarpit, 33607, Pessac, France
| | - Philippe Breton
- Institut de Recherche Servier, 125, chemin de Ronde, 78290, Croissy Sur Seine, France
| | - Brigitte Lesur
- Institut de Recherche Servier, 125, chemin de Ronde, 78290, Croissy Sur Seine, France
| | - Solo Goldstein
- Institut de Recherche Servier, 125, chemin de Ronde, 78290, Croissy Sur Seine, France
| | - Jean-Marie Fourquez
- Institut de Recherche Servier, 125, chemin de Ronde, 78290, Croissy Sur Seine, France
| | - Jean Michel Henlin
- Institut de Recherche Servier, 125, chemin de Ronde, 78290, Croissy Sur Seine, France
| | - Léon Ghosez
- IECB, CNRS UMR 5248, Université de Bordeaux, CBMN, 2, rue Robert Escarpit, 33607, Pessac, France.,UCLouvain, Place Louis Pasteur 1, 1348, Louvain-la-Neuve, Belgium
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Goodnough AM, Sahn JJ, Martin SF. Facile entry to substituted 2-arylpiperidines via an aza-Sakurai reaction. Tetrahedron Lett 2020. [DOI: 10.1016/j.tetlet.2020.151777] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
Human African trypanosomiasis (HAT) is a deadly neglected tropical disease caused by the protozoan parasite Trypanosoma brucei. During the course of screening a collection of diverse nitrogenous heterocycles, we discovered two novel compounds that contain the tetracyclic core of the Yohimbine and Corynanthe alkaloids, were potent inhibitors of T. brucei proliferation and T. brucei methionyl-tRNA synthetase (TbMetRS) activity. Inspired by these key findings, we prepared several novel series of hydroxyalkyl δ-lactam, δ-lactam, and piperidine analogs and tested their anti-trypanosomal activity. A number of inhibitors are more potent against T. brucei than these initial hits with one hydroxyalkyl δ-lactam derivative being 25-fold more effective in our assay. Surprisingly, most of these active compounds failed to inhibit TbMetRS. This work underscores the importance of verifying, irrespective of close structural similarities, that new compounds designed from a lead with a known biological target engage the putative binding site.
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Srinivasulu V, Khanfar M, Omar HA, ElAwady R, Sieburth SM, Sebastian A, Zaher DM, Al-Marzooq F, Hersi F, Al-Tel TH. Sequencing [4 + 1]-Cycloaddition and Aza-Michael Addition Reactions: A Diastereoselective Cascade for the Rapid Access of Pyrido[2′,1′:2,3]/Thiazolo[2′,3′:2,3]imidazo[1,5-a]quinolone Scaffolds as Potential Antibacterial and Anticancer Motifs. J Org Chem 2019; 84:14476-14486. [DOI: 10.1021/acs.joc.9b01919] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Vunnam Srinivasulu
- Sharjah Institute for Medical Research, University of Sharjah, P.O. Box 27272, Sharjah, UAE
| | - Monther Khanfar
- Department of Chemistry, University of Jordan, 11942 Amman, Jordan
| | - Hany A. Omar
- Sharjah Institute for Medical Research, University of Sharjah, P.O. Box 27272, Sharjah, UAE
- College of Pharmacy, University of Sharjah, P.O. Box 27272, Sharjah, UAE
| | - Raafat ElAwady
- Sharjah Institute for Medical Research, University of Sharjah, P.O. Box 27272, Sharjah, UAE
- College of Pharmacy, University of Sharjah, P.O. Box 27272, Sharjah, UAE
| | - Scott McN Sieburth
- Temple University, Department of Chemistry, 201 Beury Hall, Philadelphia, Pennsylvania 19122, United States
| | - Anusha Sebastian
- Sharjah Institute for Medical Research, University of Sharjah, P.O. Box 27272, Sharjah, UAE
| | - Dana M. Zaher
- Sharjah Institute for Medical Research, University of Sharjah, P.O. Box 27272, Sharjah, UAE
| | - Farah Al-Marzooq
- Sharjah Institute for Medical Research, University of Sharjah, P.O. Box 27272, Sharjah, UAE
| | - Fatema Hersi
- Sharjah Institute for Medical Research, University of Sharjah, P.O. Box 27272, Sharjah, UAE
| | - Taleb H. Al-Tel
- Sharjah Institute for Medical Research, University of Sharjah, P.O. Box 27272, Sharjah, UAE
- College of Pharmacy, University of Sharjah, P.O. Box 27272, Sharjah, UAE
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Berti F, Menichetti A, Favero L, Marchetti F, Pineschi M. Regio- and Stereodivergent Allylic Reductions of Bicyclic Piperidine Enecarbamate Derivatives. J Org Chem 2018; 83:12221-12228. [PMID: 30212634 DOI: 10.1021/acs.joc.8b01601] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The particular nature of tetrahydropyrido[4,3- e]-1,4,2-dioxazines of type 1 allows the regio- and stereoselective obtainment of substituted N-carbamoyl tetrahydropyridines by common reducing agents. A completely novel, biologically active, bicyclic 1,3-diaza-4-oxa-[3.3.1]-nonene scaffold can be generated by the use of lithium triethylborohydride through unprecedented cascade syn-SN2' reduction/carbamate reduction/cyclization reactions. The remarkable regioselectivity switches in the allylic reduction process have been rationalized with the aid of computational studies.
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Affiliation(s)
- Francesco Berti
- Dipartimento di Farmacia, Sede di Chimica Bioorganica e Biofarmacia , Università di Pisa , Via Bonanno 33 , 56126 Pisa , Italy
| | - Andrea Menichetti
- Dipartimento di Farmacia, Sede di Chimica Bioorganica e Biofarmacia , Università di Pisa , Via Bonanno 33 , 56126 Pisa , Italy
| | - Lucilla Favero
- Dipartimento di Farmacia, Sede di Chimica Bioorganica e Biofarmacia , Università di Pisa , Via Bonanno 33 , 56126 Pisa , Italy
| | - Fabio Marchetti
- Dipartimento di Chimica e Chimica Industriale , Università di Pisa , via G. Moruzzi 3 , 56124 , Pisa , Italy
| | - Mauro Pineschi
- Dipartimento di Farmacia, Sede di Chimica Bioorganica e Biofarmacia , Università di Pisa , Via Bonanno 33 , 56126 Pisa , Italy
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Abstract
Diverse structural types of natural products and their mimics have served as targets of opportunity in our laboratory to inspire the discovery and development of new methods and strategies to assemble polyfunctional and polycyclic molecular architectures. Furthermore, our efforts toward identifying novel compounds having useful biological properties led to the creation of new targets, many of which posed synthetic challenges that required the invention of new methodology. In this Perspective, selected examples of how we have exploited a diverse range of natural products and their mimics to create, explore, and solve a variety of problems in chemistry and biology will be discussed. The journey was not without its twists and turns, but the unexpected often led to new revelations and insights. Indeed, in our recent excursion into applications of synthetic organic chemistry to neuroscience, avoiding the more-traveled paths was richly rewarding.
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Affiliation(s)
- Stephen F Martin
- Department of Chemistry, The University of Texas at Austin , Austin, Texas 78712, United States
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11
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Zhai L, Tian X, Wang C, Cui Q, Li W, Huang SH, Yu ZX, Hong R. Construction of Morphan Derivatives by Nitroso-Ene Cyclization: Mechanistic Insight and Total Synthesis of (±)-Kopsone. Angew Chem Int Ed Engl 2017; 56:11599-11603. [DOI: 10.1002/anie.201706018] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Indexed: 12/26/2022]
Affiliation(s)
- Li Zhai
- Key Laboratory of Synthetic Chemistry of Natural Substances; Shanghai Institute of Organic Chemistry (CAS); 345 Lingling Road Shanghai 200032 China
- University of the Chinese Academy of Sciences; 19A Yuquan Road Beijing 100049 China
| | - Xuechao Tian
- School of Chemical and Environmental Engineering; Shanghai Institute of Technology; 100 Haiquan Road Shanghai 201418 China
| | - Chao Wang
- Key Laboratory of Synthetic Chemistry of Natural Substances; Shanghai Institute of Organic Chemistry (CAS); 345 Lingling Road Shanghai 200032 China
- University of the Chinese Academy of Sciences; 19A Yuquan Road Beijing 100049 China
| | - Qi Cui
- College of Chemistry; Peking University; Beijing 100871 China
| | - Wenhua Li
- Key Laboratory of Synthetic Chemistry of Natural Substances; Shanghai Institute of Organic Chemistry (CAS); 345 Lingling Road Shanghai 200032 China
- University of the Chinese Academy of Sciences; 19A Yuquan Road Beijing 100049 China
| | - Sha-Hua Huang
- School of Chemical and Environmental Engineering; Shanghai Institute of Technology; 100 Haiquan Road Shanghai 201418 China
| | - Zhi-Xiang Yu
- College of Chemistry; Peking University; Beijing 100871 China
| | - Ran Hong
- Key Laboratory of Synthetic Chemistry of Natural Substances; Shanghai Institute of Organic Chemistry (CAS); 345 Lingling Road Shanghai 200032 China
- University of the Chinese Academy of Sciences; 19A Yuquan Road Beijing 100049 China
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Construction of Morphan Derivatives by Nitroso-Ene Cyclization: Mechanistic Insight and Total Synthesis of (±)-Kopsone. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201706018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Cheng B, Sunderhaus JD, Martin SF. Applications of Ring Closing Metathesis. Total Synthesis of (±)-Pseudotabersonine. Tetrahedron 2015; 71:7323-7331. [PMID: 26300565 DOI: 10.1016/j.tet.2015.04.082] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
A novel approach to the Aspidosperma family of alkaloids was developed and applied to a concise total synthesis of (±)-pseudotabersonine that was accomplished in 11 steps. Key transformations include a stepwise variant of a Mannich-like multicomponent assembly process, a double ring-closing metathesis sequence, and a one-pot deprotection/cyclization reaction.
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Affiliation(s)
- Bo Cheng
- Department of Chemistry, The University of Texas at Austin, Austin, TX 78712
| | - James D Sunderhaus
- Department of Chemistry, The University of Texas at Austin, Austin, TX 78712
| | - Stephen F Martin
- Department of Chemistry, The University of Texas at Austin, Austin, TX 78712
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