1
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Evans MJ, Mullins J, Mondal R, Jones C. Reductions of Arenes using a Magnesium-Dinitrogen Complex. Chemistry 2024:e202401005. [PMID: 38622992 DOI: 10.1002/chem.202401005] [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: 03/11/2024] [Revised: 04/15/2024] [Accepted: 04/16/2024] [Indexed: 04/17/2024]
Abstract
In this contribution, we present "Birch-type", and other reductions of simple arenes by the potassium salt of an anionic magnesium dinitrogen complex, [{K(TCHPNON)Mg}2(μ-N2)] (TCHPNON = 4,5-bis(2,4,6-tricyclohexylanilido)-2,7-diethyl-9,9-dimethyl-xanthene), which acts as a masked dimagnesium(I) diradical in these reactions. This reagent is non-hazardous, easy-to-handle, and readily provides access to 1,4-cyclohexadiene reduction products under relatively mild reaction conditions. This system works effectively to reduce benzene, naphthalene and anthracene through magnesium-bound "Birch-type" reduction intermediates. Cyclohexadiene products can be subsequently released from the magnesium centres by protonolysis with methanol. In contrast, the reduction of substituted arenes is less selective and involves competing reaction pathways. For toluene and 1,3,5-triphenylbenzene, the structural authentication of "Birch-type" reduction intermediates is conclusive, although the formation of corresponding 1,4-cyclohexadiene derivatives was low yielding. Reduction of anisole did not yield an isolable "Birch-type" intermediate, but instead gave a C-O activation product. Treating triphenylphosphine with [{K(TCHPNON)Mg}2(μ-N2)] resulted in the extrusion of both biphenyl and dinitrogen to afford a magnesium(II) phosphanide [{K(TCHPNON)Mg(μ-PPh2)}2]. Reduction of fluorobenzene proceeded via C‒F activation of the arene, and isolation of the magnesium(II) fluoride [{K(TCHPNON)Mg(μ-F)}2]. Finally, the two-electron reduction of 1,3,5,7-cyclooctatetraene (COT) with [{K(TCHPNON)Mg}2(μ-N2)] yielded a complex, [{K(TCHPNON)Mg}2(μ-COT)], incorporating the aromatic dianion (COT2-).
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Affiliation(s)
| | | | | | - Cameron Jones
- Monash University, School of Chemistry, Box 23, 3800, Victoria, AUSTRALIA
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2
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Nallaparaju JV, Satsi R, Merzhyievskyi D, Jarg T, Aav R, Kananovich DG. Mechanochemical Birch Reduction with Low Reactive Alkaline Earth Metals. Angew Chem Int Ed Engl 2024:e202319449. [PMID: 38436590 DOI: 10.1002/anie.202319449] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 02/14/2024] [Accepted: 03/04/2024] [Indexed: 03/05/2024]
Abstract
Birch reduction and similar dissolved metal-type transformations hold significant importance in the organic synthesis toolbox. Historically, the field has been dominated by alkali metal reductants. In this study, we report that largely neglected, low-reactive alkaline earth metals can become powerful and affordable reductants when used in a ball mill under essentially solvent-free conditions, in the presence of ethylenediamine and THF as liquid additives. Calcium can reduce both electron-deficient and electron-rich arenes, with yields of products similar to those obtained with lithium metal. Magnesium reveals enhanced reducing power, enabling the reduction of benzoic acids while keeping electron-rich aromatic moieties intact and allows for chemoselective transformations. The developed mechanochemical approach uses readily available and safer-to-handle metals, operates under air and ambient temperature conditions, and can be used for gram-scale preparations. Finally, we demonstrate that the developed conditions can be used for other dissolved metal-type reductive transformations, including reductive amination, deoxygenation, dehalogenation, alkene and alkyne reductions.
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Affiliation(s)
- Jagadeesh Varma Nallaparaju
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Akadeemia tee 15, 12618, Tallinn, Estonia
| | - Riin Satsi
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Akadeemia tee 15, 12618, Tallinn, Estonia
| | - Danylo Merzhyievskyi
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Akadeemia tee 15, 12618, Tallinn, Estonia
- Department of Chemistry of Bioactive Nitrogen-containing Heterocyclic Bases, V. P. Kukhar Institute of Bioorganic Chemistry and Petrochemistry, National Academy of Sciences of Ukraine, Academician Kukhar Str. 1, 02094, Kyiv, Ukraine
| | - Tatsiana Jarg
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Akadeemia tee 15, 12618, Tallinn, Estonia
| | - Riina Aav
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Akadeemia tee 15, 12618, Tallinn, Estonia
| | - Dzmitry G Kananovich
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Akadeemia tee 15, 12618, Tallinn, Estonia
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De Luca C, Zanetti D, Battisti T, Ferreira RR, Lopez S, McMillan AH, Lesher-Pérez SC, Maggini L, Bonifazi D. Photoreduction of Anthracenes Catalyzed by peri-Xanthenoxanthene: a Scalable and Sustainable Birch-Type Alternative. Chemistry 2023; 29:e202302129. [PMID: 37593905 DOI: 10.1002/chem.202302129] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 08/17/2023] [Accepted: 08/17/2023] [Indexed: 08/19/2023]
Abstract
The typical Birch reduction transforms arenes into cyclohexa-1,4-dienes by using alkali metals, an alcohol as a proton source, and an amine as solvent. Capitalizing on the strong photoreductive properties of peri-xanthenoxanthene (PXX), herein we report the photocatalyzed "Birch-type" reduction of acenes by employing visible blue light irradiation at room temperature in the presence of air. Upon excitation at 405 or 460 nm in the presence of a mixture of N,N-diisopropylethylamine (DIPEA) and trifluoromethanesulfonimide (HNTf2 ) in DMSO, PXX photocatalyzes the selective reduction of full-carbon acene derivatives (24-75 %). Immobilization of PXX onto polydimethylsiloxane (PDMS) beads (PXX-PDMS) allowed the use of the catalyst in heterogeneous batch reactions, giving 9-phenyl-9,10-dihydroanthracene in high yield (68 %). The catalyst could easily be recovered and reused, with no notable drop in performance observed after five reaction cycles. Integration of the PXX-PDMS beads into a microreactor enabled the reduction of acenes under continuous-flow conditions, thereby validating the sustainability and scalability of this heterogeneous-phase approach.
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Affiliation(s)
- Cristian De Luca
- Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090, Vienna, Austria
| | - Davide Zanetti
- Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090, Vienna, Austria
| | - Tommaso Battisti
- School of Chemistry, Cardiff University, Park Place, CF10 3AT, Cardiff, UK
| | - Rúben R Ferreira
- Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090, Vienna, Austria
| | - Sofia Lopez
- División Polímeros Nanoestructurados, Instituto de Investigaciones en Ciencia y Tecnología de Materiales (INTEMA), UNMdP-CONICET y Departamento de Química, UNMdP, Av. Cristóbal Colón 10850, Mar del Plata, B7606BWV, Buenos Aires, Argentina
| | | | - Sasha Cai Lesher-Pérez
- Department of Chemical Engineering, Department of Biomedical Engineering, University of Michigan, North Campus Research Complex Building 28, 2800 Plymouth Rd, 48109-2800, Ann Arbor, MI, USA
| | - Laura Maggini
- Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090, Vienna, Austria
| | - Davide Bonifazi
- Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090, Vienna, Austria
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4
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Si XG, Feng SX, Wang ZY, Chen X, Xu MM, Zhang YZ, He JX, Yang L, Cai Q. Enantioselective Synthesis of cis-Decalins by Merging the Birch Reduction and Inverse-Electron-Demand Diels-Alder Reaction. Angew Chem Int Ed Engl 2023:e202303876. [PMID: 37286494 DOI: 10.1002/anie.202303876] [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: 03/17/2023] [Revised: 06/07/2023] [Accepted: 06/07/2023] [Indexed: 06/09/2023]
Abstract
Herein, we show the combination of the Birch reduction of readily available anisole derivatives and the catalytic asymmetric inverse-electron-demand Diels-Alder reaction of 2-pyrones can serve as a powerful platform for the diverse synthesis of synthetically important cis-decalin scaffolds. Enabled by a well-modified chiral bis(oxazoline) ligand/Cu(II) complex, a wide range of polysubstituted cis-decalin scaffolds with up to six continuous stereocenters was generated efficiently. The synthetic potential of this method is demonstrated by the concise synthesis of sesquiterpene (+)-occidentalol and a key intermediate for seven triterpenes. Mechanistic studies suggest the in situ formed 1,3-cyclohexadienes are the key intermediates, and efficient kinetic resolution occurs when C2 and/or C3 substituted 1,4-cyclohexadienes are utilized as substrates. DFT calculations elucidate the Diels-Alder reaction proceeds in a stepwise fashion, and reveal the originations of the stereoselectivities.
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Affiliation(s)
- Xu-Ge Si
- Fudan University, Chemistry Department, CHINA
| | | | | | - Xiaoyu Chen
- Hangzhou Normal University, College of Materials, Chemistry and Chemical Engineering, CHINA
| | | | | | | | - Limin Yang
- Hangzhou Normal University, College of Materials, Chemistry & Chemical Engineering, CHINA
| | - Quan Cai
- Fudan University, Department of Chemistry, 220 Handan Rd., 200433, Shanghai, CHINA
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Gao Y, Kubota K, Ito H. Mechanochemical Approach for Air-Tolerant and Extremely Fast Lithium-Based Birch Reductions in Minutes. Angew Chem Int Ed Engl 2023; 62:e202217723. [PMID: 36944574 DOI: 10.1002/anie.202217723] [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: 12/02/2022] [Revised: 03/21/2023] [Accepted: 03/21/2023] [Indexed: 03/23/2023]
Abstract
Birch reduction has been widely used in organic synthesis for over half a century as a powerful method to dearomatize arenes into 1,4-cyclohexadiene derivatives. However, the conventional Birch reduction reaction using liquid ammonia requires laborious procedures to ensure inert conditions and low temperatures. Although several ammonia-free modifications have been reported, the development of an operationally simple, efficient, and scalable protocol remains a challenge. Herein, we report an ammonia-free lithium-based Birch reduction in air at room temperature without special operating conditions using a ball-milling technique. This method is characterized by its operational simplicity and an extremely short reaction time (within 1 min), probably owing to the in-situ mechanical activation of lithium metal, broad substrate scope, and no requirement for dry bulk solvents. The potential of our flash Birch reaction is also demonstrated by the efficient reduction of bioactive target molecules and gram-scale synthesis.
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Affiliation(s)
- Yunpeng Gao
- Hokkaido University: Hokkaido Daigaku, Division of Applied Chemistry, JAPAN
| | - Koji Kubota
- Hokkaido University: Hokkaido Daigaku, Division of Applied Chemistry, JAPAN
| | - Hajime Ito
- Hokkaido University, Division of Applied Chemistry, Kita-13 Nishi-8, Kita-ku, 060-8628, Sapporo, JAPAN
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Karns AS, Ellis BD, Roosen PC, Chahine Z, Le Roch KG, Vanderwal CD. Concise Synthesis of the Antiplasmodial Isocyanoterpene 7,20-Diisocyanoadociane. Angew Chem Int Ed Engl 2019; 58:13749-13752. [PMID: 31270921 DOI: 10.1002/anie.201906834] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [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: 06/01/2019] [Indexed: 01/08/2023]
Abstract
The flagship member of the antiplasmodial isocyanoterpenes, 7,20-diisocyanoadociane (DICA), was synthesized from dehydrocryptone in 10 steps, and in 13 steps from commercially available material. Our previous formal synthesis was reengineered, leveraging only productive transformations to deliver DICA in fewer than half the number of steps of our original effort. Important contributions, in addition to the particularly concise strategy, include a solution to the problem of axial nucleophilic methylation of a late-stage cyclohexanone, and the first selective synthesis and antiplasmodial evaluation of the DICA stereoisomer with both isonitriles equatorial.
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Affiliation(s)
- Alexander S Karns
- 1102 Natural Sciences II, Department of Chemistry, University of California, Irvine, CA, 92697-2025, USA
| | - Bryan D Ellis
- 1102 Natural Sciences II, Department of Chemistry, University of California, Irvine, CA, 92697-2025, USA
| | - Philipp C Roosen
- 1102 Natural Sciences II, Department of Chemistry, University of California, Irvine, CA, 92697-2025, USA
| | - Zeinab Chahine
- Institute for Integrative Genome Biology, Center for Infectious Disease and Vector Research, Department of Molecular, Cell, and Systems Biology, University of California, Riverside, 900 University Avenue, Riverside, CA, 92521, USA
| | - Karine G Le Roch
- Institute for Integrative Genome Biology, Center for Infectious Disease and Vector Research, Department of Molecular, Cell, and Systems Biology, University of California, Riverside, 900 University Avenue, Riverside, CA, 92521, USA
| | - Christopher D Vanderwal
- 1102 Natural Sciences II, Department of Chemistry, University of California, Irvine, CA, 92697-2025, USA
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7
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Tiedt O, Fuchs J, Eisenreich W, Boll M. A catalytically versatile benzoyl-CoA reductase, key enzyme in the degradation of methyl- and halobenzoates in denitrifying bacteria. J Biol Chem 2018; 293:10264-10274. [PMID: 29769313 DOI: 10.1074/jbc.ra118.003329] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 05/15/2018] [Indexed: 12/22/2022] Open
Abstract
Class I benzoyl-CoA (BzCoA) reductases (BCRs) are key enzymes in the anaerobic degradation of aromatic compounds. They catalyze the ATP-dependent reduction of the central BzCoA intermediate and analogues of it to conjugated cyclic 1,5-dienoyl-CoAs probably by a radical-based, Birch-like reduction mechanism. Discovered in 1995, the enzyme from the denitrifying bacterium Thauera aromatica (BCRTar) has so far remained the only isolated and biochemically accessible BCR, mainly because BCRs are extremely labile, and their heterologous production has largely failed so far. Here, we describe a platform for the heterologous expression of the four structural genes encoding a designated 3-methylbenzoyl-CoA reductase from the related denitrifying species Thauera chlorobenzoica (MBRTcl) in Escherichia coli This reductase represents the prototype of a distinct subclass of ATP-dependent BCRs that were proposed to be involved in the degradation of methyl-substituted BzCoA analogues. The recombinant MBRTcl had an αβγδ-subunit architecture, contained three low-potential [4Fe-4S] clusters, and was highly oxygen-labile. It catalyzed the ATP-dependent reductive dearomatization of BzCoA with 2.3-2.8 ATPs hydrolyzed per two electrons transferred and preferentially dearomatized methyl- and chloro-substituted analogues in meta- and para-positions. NMR analyses revealed that 3-methylbenzoyl-CoA is regioselectively reduced to 3-methyl-1,5-dienoyl-CoA. The unprecedented reductive dechlorination of 4-chloro-BzCoA to BzCoA probably via HCl elimination from a reduced intermediate allowed for the previously unreported growth of T. chlorobenzoica on 4-chlorobenzoate. The heterologous expression platform established in this work enables the production, isolation, and characterization of bacterial and archaeal BCR and BCR-like radical enzymes, for many of which the function has remained unknown.
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Affiliation(s)
- Oliver Tiedt
- From the Fakultät für Biologie-Mikrobiologie, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg, Germany and
| | - Jonathan Fuchs
- From the Fakultät für Biologie-Mikrobiologie, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg, Germany and
| | - Wolfgang Eisenreich
- Lehrstuhl für Biochemie, Technische Universität München, 85747 Garching, Germany
| | - Matthias Boll
- From the Fakultät für Biologie-Mikrobiologie, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg, Germany and
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Whitener KE, Lee WK, Bassim ND, Stroud RM, Robinson JT, Sheehan PE. Transfer of Chemically Modified Graphene with Retention of Functionality for Surface Engineering. Nano Lett 2016; 16:1455-1461. [PMID: 26784372 DOI: 10.1021/acs.nanolett.5b05073] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Single-layer graphene chemically reduced by the Birch process delaminates from a Si/SiOx substrate when exposed to an ethanol/water mixture, enabling transfer of chemically functionalized graphene to arbitrary substrates such as metals, dielectrics, and polymers. Unlike in previous reports, the graphene retains hydrogen, methyl, and aryl functional groups during the transfer process. This enables one to functionalize the receiving substrate with the properties of the chemically modified graphene (CMG). For instance, magnetic force microscopy shows that the previously reported magnetic properties of partially hydrogenated graphene remain after transfer. We also transfer hydrogenated graphene from its copper growth substrate to a Si/SiOx wafer and thermally dehydrogenate it to demonstrate a polymer- and etchant-free graphene transfer for potential use in transmission electron microscopy. Finally, we show that the Birch reduction facilitates delamination of CMG by weakening van der Waals forces between graphene and its substrate.
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Affiliation(s)
- Keith E Whitener
- Chemistry Division, ‡Materials Science and Technology Division, and §Electronic Science and Technology Division, U.S. Naval Research Laboratory , Washington, D.C. 20375, United States
| | - Woo-Kyung Lee
- Chemistry Division, ‡Materials Science and Technology Division, and §Electronic Science and Technology Division, U.S. Naval Research Laboratory , Washington, D.C. 20375, United States
| | - Nabil D Bassim
- Chemistry Division, ‡Materials Science and Technology Division, and §Electronic Science and Technology Division, U.S. Naval Research Laboratory , Washington, D.C. 20375, United States
| | - Rhonda M Stroud
- Chemistry Division, ‡Materials Science and Technology Division, and §Electronic Science and Technology Division, U.S. Naval Research Laboratory , Washington, D.C. 20375, United States
| | - Jeremy T Robinson
- Chemistry Division, ‡Materials Science and Technology Division, and §Electronic Science and Technology Division, U.S. Naval Research Laboratory , Washington, D.C. 20375, United States
| | - Paul E Sheehan
- Chemistry Division, ‡Materials Science and Technology Division, and §Electronic Science and Technology Division, U.S. Naval Research Laboratory , Washington, D.C. 20375, United States
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Schneider G, Kiss A, Mernyák E, Benke Z, Wölfling J, Frank É, Bózsity N, Gyovai A, Minorics R, Zupkó I. Stereocontrolled synthesis of the four 16-hydroxymethyl-19-nortestosterone isomers and their antiproliferative activities. Steroids 2016; 105:113-20. [PMID: 26686898 DOI: 10.1016/j.steroids.2015.12.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 11/11/2015] [Accepted: 12/01/2015] [Indexed: 11/22/2022]
Abstract
Novel 16-hydroxymethyl-19-nortestosterone diastereomers were prepared by Birch reduction from the corresponding 3-methoxy-16-hydroxymethylestra-1,3,5(10)-trien-17-ol isomers with known configurations. The synthesized compounds are 16α- and 16β-hydroxymethyl-substituted 19-nortestosterone and their 17α-epimers. To prepare 17α-19-nortestosterone, the Mitsunobu inversion reaction of 19-nortestosterone with different alkyl and aryl carboxylic acids was chosen. Deacylation of the new compounds by the Zemplén method yielded the required 17α-19-nortestosterone. The antiproliferative activities of the structurally related compounds were determined in vitro through microculture tetrazolium assays on a panel of human adherent cervical (HeLa, SiHa and C33A), breast (MCF-7, MDA-MB-231, MDA-MB-361 and T47D) and ovarian (A2780) cell lines. The 17α epimer of 19-nortestosterone demonstrated considerable activity, selectively for HeLa cells, with a calculated IC50 of 0.65 μM. The reference compound, cisplatin, displayed an order of magnitude higher IC50 (12.4 μM). The cancer selectivity of 17α-19-nortestosterone was tested by MTT assay performed with noncancerous human fibroblast cell line MRC-5. The results indicated that 17α-19-nortestosterone selectively disturbs the viability of HeLa cells without greatly affecting other cancer cell types and intact fibroblasts.
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Affiliation(s)
- Gyula Schneider
- Department of Organic Chemistry, University of Szeged, Dóm tér 8., H-6720 Szeged, Hungary.
| | - Anita Kiss
- Department of Organic Chemistry, University of Szeged, Dóm tér 8., H-6720 Szeged, Hungary
| | - Erzsébet Mernyák
- Department of Organic Chemistry, University of Szeged, Dóm tér 8., H-6720 Szeged, Hungary
| | - Zsanett Benke
- Department of Organic Chemistry, University of Szeged, Dóm tér 8., H-6720 Szeged, Hungary
| | - János Wölfling
- Department of Organic Chemistry, University of Szeged, Dóm tér 8., H-6720 Szeged, Hungary
| | - Éva Frank
- Department of Organic Chemistry, University of Szeged, Dóm tér 8., H-6720 Szeged, Hungary
| | - Noémi Bózsity
- Department of Pharmacodynamics and Biopharmacy, University of Szeged, Eötvös u. 6., H-6720 Szeged, Hungary
| | - András Gyovai
- Department of Pharmacodynamics and Biopharmacy, University of Szeged, Eötvös u. 6., H-6720 Szeged, Hungary
| | - Renáta Minorics
- Department of Pharmacodynamics and Biopharmacy, University of Szeged, Eötvös u. 6., H-6720 Szeged, Hungary
| | - István Zupkó
- Department of Pharmacodynamics and Biopharmacy, University of Szeged, Eötvös u. 6., H-6720 Szeged, Hungary.
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Liu C, Xie F, Zhao GD, Wang DF, Lou HX, Liu ZP. Synthetic studies towards 1α-hydroxysolasodine from diosgenin and the unexpected tetrahydrofuran ring opening in the Birch reduction process. Steroids 2015; 104:214-9. [PMID: 26476186 DOI: 10.1016/j.steroids.2015.10.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 09/17/2015] [Accepted: 10/09/2015] [Indexed: 12/11/2022]
Abstract
The synthesis of 1α-hydroxysolasodine from diosgenin was attempted. The Pd/C catalyst mediated dehydrogenation of diosgenin generated the 1,4,6-trien-3-one (3), which was reacted with Ac2O in pyridine in the presence of a catalytic amount of POCl3 followed by hydrolysis to give the 22-hydroxyfurostan (4) in 65% yield. Conversion of the primary 26-OH group into the azide and simultaneously 22-OH dehydration were achieved in one step by Mitsunobu reaction. Treatment of the (25R)-26-azidofurosta-1,4,6,20(22)-tetraen-3-one (5) with chlorotrimethylsilane (TMSCl)/NaI/MeCN and cyclisation in situ provided the (22R,25R)-spirosola-1,4,6-trien-3-one (6) in good yield. Stereoselective and regioselective epoxidation of trienone (6) with 30% H2O2 and 5% NaOH in methanol gave the 1α,2α-epoxy-(22R,25R)-spirosola-4,6-dien-3-one (7). Birch reduction of the epoxide (7) with Li/NH3 in THF followed by the treatment with NH4Cl, however, failed to generate the expected 1α-hydroxysolasodine, but provided a tetrahydrofuran ring opening product, (22S,25R)-1α,16β-dihydroxy-22,26-epiminocholest-4-en-3-one (8). Compounds 3 and 5-8 as well as solasodine were evaluated for their cell growth inhibitory activities against human prostate cancer PC3, human cervical carcinoma Hela, and human hepatoma HepG2 cells. At the concentration of 10 μM, only epoxide 7 displayed moderate inhibitory rates towards these cells (40-54%).
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Affiliation(s)
- Chao Liu
- Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, Jinan 250012, PR China
| | - Fei Xie
- Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, Jinan 250012, PR China
| | - Guo-Dong Zhao
- Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, Jinan 250012, PR China
| | - De-Feng Wang
- Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, Jinan 250012, PR China
| | - Hong-Xiang Lou
- Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, Jinan 250012, PR China.
| | - Zhao-Peng Liu
- Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, Jinan 250012, PR China.
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11
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Yu X, Guttenberger N, Fuchs E, Peters M, Weber H, Breinbauer R. Diversity-Oriented Synthesis of a Library of Star-Shaped 2H-Imidazolines. ACS Comb Sci 2015; 17:682-90. [PMID: 26402035 DOI: 10.1021/acscombsci.5b00107] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
A library of star-shaped 2H-imidazolines has been synthesized via Debus-Radziszewski condensation from 1,2-diketones and ketone starting materials. Selective reduction of one imine group of the 2H-imidazole intermediate with LiAlH4 or catalytic flow hydrogenation furnished 2H-imidazolines, which could be conveniently diversified by reacting the amine N with electrophiles, resulting in a set of 21 amide-, carbamate-, urea-, and allylamine-containing products. In total, five points of diversification could be used, which allow the production of a set of functionally diverse compounds. The synthesis of acylated 2H-imidazolidines resulted in intrinsically labile compounds, which spontaneously degraded to acyclic derivatives, as shown for the reaction of 2H-imidazolidine with hexylisocyanate.
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Affiliation(s)
- Xuepu Yu
- Institute of Organic Chemistry, Graz University of Technology, A-8010 Graz, Austria
| | | | - Elisabeth Fuchs
- Institute of Organic Chemistry, Graz University of Technology, A-8010 Graz, Austria
| | - Martin Peters
- Institute of Organic Chemistry, Graz University of Technology, A-8010 Graz, Austria
| | - Hansjörg Weber
- Institute of Organic Chemistry, Graz University of Technology, A-8010 Graz, Austria
| | - Rolf Breinbauer
- Institute of Organic Chemistry, Graz University of Technology, A-8010 Graz, Austria
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Abstract
The synthesis of three Lex derivatives from one common protected trisaccharide is reported. These analogues will be used respectively for competitive binding experiments, conjugation to carrier proteins and immobilization on gold. An N-acetylglucosamine monosaccharide acceptor was first glycosylated at O-4 with a galactosyl imidate. This coupling was performed at 40 °C under excess of BF3·OEt2 activation and proceeded best if the acceptor carried a 6-chlorohexyl rather than a 6-azidohexyl aglycon. The 6-chlorohexyl disaccharide was then converted to an acceptor and submitted to fucosylation yielding the corresponding protected 6-chlorohexyl Lex trisaccharide. This protected trisaccharide was used as a precursor to the 6-azidohexyl, 6-acetylthiohexyl and 6-benzylthiohexyl trisaccharide analogues which were obtained in excellent yields (70–95%). In turn, we describe the deprotection of these intermediates in one single step using dissolving metal conditions. Under these conditions, the 6-chlorohexyl and 6-azidohexyl intermediates led respectively to the n-hexyl and 6-aminohexyl trisaccharide targets. Unexpectedly, the 6-acetylthiohexyl analogue underwent desulfurization and gave the n-hexyl glycoside product, whereas the 6-benzylthiohexyl analogue gave the desired disulfide trisaccharide dimer. This study constitutes a particularly efficient and convergent preparation of these three Lex analogues.
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Affiliation(s)
- An Wang
- Department of Chemistry, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
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