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Metternich JB, Reiterer M, Jacobsen EN. Asymmetric Nazarov Cyclizations of Unactivated Dienones by Hydrogen-Bond-Donor/Lewis Acid Co-Catalyzed, Enantioselective Proton-Transfer. Adv Synth Catal 2020; 362:4092-4097. [PMID: 33162875 PMCID: PMC7643875 DOI: 10.1002/adsc.202000831] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Indexed: 12/15/2022]
Abstract
We report an enantioselective Nazarov cyclization catalyzed by chiral hydrogen-bond-donors in concert with silyl Lewis acids. The developed transformation provides access to tri-substituted cyclopentenones in high levels of enantioselectivity (up to 95% e.e.) from a variety of simple unactivated dienones. Kinetic and mechanistic studies are consistent with a reversible 4π-electrocyclization C-C bond-forming step followed by rate- and enantio-determining proton-transfer as the mode of catalysis.
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Affiliation(s)
- Jan B Metternich
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Martin Reiterer
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Eric N Jacobsen
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
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2
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Novel d-Annulated Pentacyclic Steroids: Regioselective Synthesis and Biological Evaluation in Breast Cancer Cells. Molecules 2020; 25:molecules25153499. [PMID: 32752019 PMCID: PMC7435891 DOI: 10.3390/molecules25153499] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 07/29/2020] [Accepted: 07/30/2020] [Indexed: 12/19/2022] Open
Abstract
The acid-catalyzed cyclization of benzylidenes based on 16-dehydropregnenolone acetate (16-DPA) was studied. It was found that these compounds readily undergo regioselective interrupted Nazarov cyclization with trapping chloride ion and an efficient method of the synthesis of d-annulated pentacyclic steroids based on this reaction was proposed. The structures of the synthesized pentacyclic steroids were determined by NMR and X-ray diffraction. It was found that the reaction affords a single diastereomer, but the latter can crystallize as two conformers depending on the structure. Antiproliferative activity of synthesized compounds was evaluated against two breast cancer cell lines: MCF-7 and MDA-MB-231. All tested compounds showed relatively high antiproliferative activity. The synthetic potential of the protocol developed was illustrated by the gram-scale experiment.
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3
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Plaza M, Jandl C, Bach T. Photochemical Deracemization of Allenes and Subsequent Chirality Transfer. Angew Chem Int Ed Engl 2020; 59:12785-12788. [PMID: 32390291 PMCID: PMC7537568 DOI: 10.1002/anie.202004797] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Indexed: 12/29/2022]
Abstract
Trisubstituted allenes with a 3-(1'-alkenylidene)-pyrrolidin-2-one motif were successfully deracemized (13 examples, 86-98 % ee) employing visible light (λ=420 nm) and a chiral triplet sensitizer as the catalyst (2.5 mol %). The photocatalyst likely operates by selective recognition of one allene enantiomer via hydrogen bonds and by a triplet-sensitized racemization process. Even a tetrasubstituted allene (45 % ee) and a seven-membered 3-(1'-alkenylidene)-azepan-2-one (62 % ee) could be enantiomerically enriched under the chosen conditions. It was shown that the axial chirality of the allenes can be converted into point chirality by a Diels-Alder (94-97 % ee) or a bromination reaction (91 % ee). Ring opening of the five-membered pyrrolidin-2-one was achieved without significantly compromising the integrity of the chirality axis (92 % ee).
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Affiliation(s)
- Manuel Plaza
- Department Chemie and Catalysis Research Center (CRC)Technische Universität MünchenLichtenbergstrasse 485747GarchingGermany
| | - Christian Jandl
- Department Chemie and Catalysis Research Center (CRC)Technische Universität MünchenLichtenbergstrasse 485747GarchingGermany
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC)Technische Universität MünchenLichtenbergstrasse 485747GarchingGermany
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4
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Plaza M, Jandl C, Bach T. Photochemical Deracemization of Allenes and Subsequent Chirality Transfer. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202004797] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Manuel Plaza
- Department Chemie and Catalysis Research Center (CRC) Technische Universität München Lichtenbergstrasse 4 85747 Garching Germany
| | - Christian Jandl
- Department Chemie and Catalysis Research Center (CRC) Technische Universität München Lichtenbergstrasse 4 85747 Garching Germany
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC) Technische Universität München Lichtenbergstrasse 4 85747 Garching Germany
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5
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Aota Y, Doko Y, Kano T, Maruoka K. Brønsted Acid-Catalyzed Intramolecular α-Arylation of Ketones with Phenolic Nucleophiles via Oxy-Allyl Cation Intermediates. European J Org Chem 2020. [DOI: 10.1002/ejoc.202000169] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Yusuke Aota
- Department of Chemistry; Graduate School of Science; Kyoto University; Sakyo 606-8502 Kyoto Japan
| | - Yuki Doko
- Department of Chemistry; Graduate School of Science; Kyoto University; Sakyo 606-8502 Kyoto Japan
| | - Taichi Kano
- Department of Chemistry; Graduate School of Science; Kyoto University; Sakyo 606-8502 Kyoto Japan
| | - Keiji Maruoka
- Department of Chemistry; Graduate School of Science; Kyoto University; Sakyo 606-8502 Kyoto Japan
- Graduate School of Pharmaceutical Sciences; Kyoto University; Sakyo 606-8501 Kyoto Japan
- School of Chemical Engineering and Light Industry; Guangdong University of Technology; 510006 Guangzhou China
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6
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Affiliation(s)
- Anton V. Yadykov
- N. D. Zelinsky Institute of Organic ChemistryRussian Academy of Sciences 47 Leninsky prosp., 119991 Moscow Russian Federation
| | - Valerii Z. Shirinian
- N. D. Zelinsky Institute of Organic ChemistryRussian Academy of Sciences 47 Leninsky prosp., 119991 Moscow Russian Federation
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7
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Alachouzos G, Frontier AJ. Diastereoselective Construction of Densely Functionalized 1‐Halocyclopentenes Using an Alkynyl Halo‐Prins/Halo‐Nazarov Cyclization Strategy. Angew Chem Int Ed Engl 2017; 56:15030-15034. [DOI: 10.1002/anie.201709482] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Indexed: 12/29/2022]
Affiliation(s)
- Georgios Alachouzos
- Department of Chemistry University of Rochester 414 Hutchison Hall, 100 Trustee Road Rochester NY 14627-0216 USA
| | - Alison J. Frontier
- Department of Chemistry University of Rochester 414 Hutchison Hall, 100 Trustee Road Rochester NY 14627-0216 USA
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8
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Alachouzos G, Frontier AJ. Diastereoselective Construction of Densely Functionalized 1‐Halocyclopentenes Using an Alkynyl Halo‐Prins/Halo‐Nazarov Cyclization Strategy. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201709482] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Georgios Alachouzos
- Department of Chemistry University of Rochester 414 Hutchison Hall, 100 Trustee Road Rochester NY 14627-0216 USA
| | - Alison J. Frontier
- Department of Chemistry University of Rochester 414 Hutchison Hall, 100 Trustee Road Rochester NY 14627-0216 USA
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9
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Vinogradov MG, Turova OV, Zlotin SG. Nazarov reaction: current trends and recent advances in the synthesis of natural compounds and their analogs. Org Biomol Chem 2017; 15:8245-8269. [DOI: 10.1039/c7ob01981e] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Recent applications of the Nazarov reaction to stereoselective synthesis of pharmacology-relevant cyclopentenone scaffolds are summarized.
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Affiliation(s)
- Maxim G. Vinogradov
- N.D. Zelinsky Institute of Organic Chemistry
- Russian Academy of Sciences
- 119991 Moscow
- Russian Federation
| | - Olga V. Turova
- N.D. Zelinsky Institute of Organic Chemistry
- Russian Academy of Sciences
- 119991 Moscow
- Russian Federation
| | - Sergei G. Zlotin
- N.D. Zelinsky Institute of Organic Chemistry
- Russian Academy of Sciences
- 119991 Moscow
- Russian Federation
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10
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Schatz DJ, Kwon Y, Scully TW, West FG. Interrupting the Nazarov Cyclization with Bromine. J Org Chem 2016; 81:12494-12498. [PMID: 27978732 DOI: 10.1021/acs.joc.6b02350] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The generation of dibrominated cyclopentenones via an interrupted Nazarov cyclization is reported. The installation of two bromine atoms occurs at the α and α' positions of the cyclopentenyl scaffold via successive nucleophilic and electrophilic bromination of the 2-oxidocyclopentenyl cation and its resulting enolate. Notably, the reaction proceeds with good diastereoselectivity, favoring the symmetrical product.
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Affiliation(s)
- Devon J Schatz
- Department of Chemistry, University of Alberta , E3-43 Gunning-Lemieux Chemistry Centre, Edmonton, AB, Canada
| | - Yonghoon Kwon
- Department of Chemistry, University of Alberta , E3-43 Gunning-Lemieux Chemistry Centre, Edmonton, AB, Canada
| | - Thomas W Scully
- Department of Chemistry, University of Alberta , E3-43 Gunning-Lemieux Chemistry Centre, Edmonton, AB, Canada
| | - F G West
- Department of Chemistry, University of Alberta , E3-43 Gunning-Lemieux Chemistry Centre, Edmonton, AB, Canada
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11
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William R, Wang S, Mallick A, Liu XW. Interrupting Nazarov Reaction with Different Trapping Modality: Utilizing Potassium Alkynyltrifluoroborate as a σ-Nucleophile. Org Lett 2016; 18:4458-61. [DOI: 10.1021/acs.orglett.6b01606] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ronny William
- Division
of Chemistry and
Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Siming Wang
- Division
of Chemistry and
Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Asadulla Mallick
- Division
of Chemistry and
Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Xue-Wei Liu
- Division
of Chemistry and
Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
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12
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Li Z, Boyd RJ, Burnell DJ. Computational Examination of (4 + 3) versus (3 + 2) Cycloaddition in the Interception of Nazarov Reactions of Allenyl Vinyl Ketones by Dienes. J Org Chem 2015; 80:12535-44. [PMID: 26595587 DOI: 10.1021/acs.joc.5b02397] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A computational examination of the tandem Nazarov/cycloaddition process involving an allenyl vinyl ketone with a diene has been carried out using the ωB97X-D/6-311++G(d,p)//ωB97X-D/6-31+G(d,p) method with solvation modeled by SMD-PCM. The barrier for the initial Lewis acid mediated Nazarov reaction, which provided the intermediate cyclic oxylallyl cation, was higher than that for any subsequent cycloaddition. The barrier for the first step of a subsequent stepwise reaction did not vary much with the diene, and the lowest barrier was with the diene in its s-trans conformation. Stepwise formation of a (4 + 3) cycloaddition product was not energetically feasible, but (3 + 2) cycloaddition products could have been produced through low energy pathways. The barrier for a concerted (4 + 3) cycloaddition did depend upon the diene, which was always in an s-cis geometry. The barriers for the compact and the extended geometries for the transition states of (4 + 3) cycloadditions were not much different.
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Affiliation(s)
- Zhe Li
- Department of Chemistry, Dalhousie University , P.O. Box 15000, Halifax, Nova Scotia B3H 4R2, Canada
| | - Russell J Boyd
- Department of Chemistry, Dalhousie University , P.O. Box 15000, Halifax, Nova Scotia B3H 4R2, Canada
| | - D Jean Burnell
- Department of Chemistry, Dalhousie University , P.O. Box 15000, Halifax, Nova Scotia B3H 4R2, Canada
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13
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LeFort FM, Mishra V, Dexter GD, Morgan TDR, Burnell DJ. Nazarov Reactions Intercepted by (4 + 3) Cycloadditions with Oxygen-Substituted Dienes. J Org Chem 2015; 80:5877-86. [DOI: 10.1021/acs.joc.5b00914] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- François M. LeFort
- Department
of Chemistry, Dalhousie University,
P.O. Box 15000, Halifax, Nova Scotia B3H 4R2, Canada
| | - Vinayak Mishra
- Department
of Chemistry, Dalhousie University,
P.O. Box 15000, Halifax, Nova Scotia B3H 4R2, Canada
| | - Graham D. Dexter
- Department
of Chemistry, Dalhousie University,
P.O. Box 15000, Halifax, Nova Scotia B3H 4R2, Canada
| | - Timothy D. R. Morgan
- Department
of Chemistry, Dalhousie University,
P.O. Box 15000, Halifax, Nova Scotia B3H 4R2, Canada
| | - D. Jean Burnell
- Department
of Chemistry, Dalhousie University,
P.O. Box 15000, Halifax, Nova Scotia B3H 4R2, Canada
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14
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Morgan TDR, LeFort FM, Li Z, Marx VM, Boyd RJ, Burnell DJ. Interception of Nazarov Reactions of Allenyl Vinyl Ketones with Dienes: (3+2)- versus (4+3)-Cycloaddition and Subsequent Rearrangement. European J Org Chem 2015. [DOI: 10.1002/ejoc.201403618] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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15
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Sudhakar G, Satish K. Nazarov Cyclization of Divinyl and Arylvinyl Epoxides: Application in the Synthesis of Resveratrol-Based Natural Products. Chemistry 2015; 21:6475-80. [DOI: 10.1002/chem.201500362] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Indexed: 11/05/2022]
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16
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Morgan TDR, LeBlanc LM, Ardagh GH, Boyd RJ, Burnell DJ. Torquoselectivity in the Nazarov Reactions of Allenyl Vinyl Ketones. J Org Chem 2015; 80:1042-51. [DOI: 10.1021/jo502532a] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Timothy D. R. Morgan
- Department of Chemistry, Dalhousie University,
P.O. Box 15000, Halifax, Nova Scotia B3H 4R2, Canada
| | - Luc M. LeBlanc
- Department of Chemistry, Dalhousie University,
P.O. Box 15000, Halifax, Nova Scotia B3H 4R2, Canada
| | - Giselle H. Ardagh
- Department of Chemistry, Dalhousie University,
P.O. Box 15000, Halifax, Nova Scotia B3H 4R2, Canada
| | - Russell J. Boyd
- Department of Chemistry, Dalhousie University,
P.O. Box 15000, Halifax, Nova Scotia B3H 4R2, Canada
| | - D. Jean Burnell
- Department of Chemistry, Dalhousie University,
P.O. Box 15000, Halifax, Nova Scotia B3H 4R2, Canada
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17
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Wu YK, Dunbar CR, McDonald R, Ferguson MJ, West FG. Experimental and Computational Studies on Interrupted Nazarov Reactions: Exploration of Umpolung Reactivity at the α-Carbon of Cyclopentanones. J Am Chem Soc 2014; 136:14903-11. [DOI: 10.1021/ja507638r] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Yen-Ku Wu
- X-ray Crystallography Lab, †Department of Chemistry, University of Alberta, E3-43 Gunning-Lemieux Chemistry Center, Edmonton, Alberta T6G 2G2, Canada
| | - Christine R. Dunbar
- X-ray Crystallography Lab, †Department of Chemistry, University of Alberta, E3-43 Gunning-Lemieux Chemistry Center, Edmonton, Alberta T6G 2G2, Canada
| | - Robert McDonald
- X-ray Crystallography Lab, †Department of Chemistry, University of Alberta, E3-43 Gunning-Lemieux Chemistry Center, Edmonton, Alberta T6G 2G2, Canada
| | - Michael J. Ferguson
- X-ray Crystallography Lab, †Department of Chemistry, University of Alberta, E3-43 Gunning-Lemieux Chemistry Center, Edmonton, Alberta T6G 2G2, Canada
| | - F. G. West
- X-ray Crystallography Lab, †Department of Chemistry, University of Alberta, E3-43 Gunning-Lemieux Chemistry Center, Edmonton, Alberta T6G 2G2, Canada
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18
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Haneishi T, Hachiya I, Shimizu M. Titanium Tetraiodide-Mediated Organic Reactions. ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2014. [DOI: 10.1007/s13369-014-1191-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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19
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Wu YK, West FG. Formal Homologous Aldol Reactions: Interrupting the Nazarov Cyclization via Carboalkoxylation of Alkynes. Org Lett 2014; 16:2534-7. [DOI: 10.1021/ol500914a] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Yen-Ku Wu
- Department
of Chemistry, University of Alberta, E3-43 Gunning-Lemieux Chemistry
Center, Edmonton, AB T6G
2G2, Canada
| | - F. G. West
- Department
of Chemistry, University of Alberta, E3-43 Gunning-Lemieux Chemistry
Center, Edmonton, AB T6G
2G2, Canada
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21
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Kwon Y, McDonald R, West FG. Organoaluminum-Mediated Interrupted Nazarov Reaction. Angew Chem Int Ed Engl 2013; 52:8616-9. [DOI: 10.1002/anie.201303996] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 06/07/2013] [Indexed: 11/10/2022]
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22
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Kwon Y, McDonald R, West FG. Organoaluminum-Mediated Interrupted Nazarov Reaction. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201303996] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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23
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Lebœuf D, Theiste E, Gandon V, Daifuku SL, Neidig ML, Frontier AJ. Efficient Nazarov cyclization/Wagner-Meerwein rearrangement terminated by a Cu(II)-promoted oxidation: synthesis of 4-alkylidene cyclopentenones. Chemistry 2013; 19:4842-8. [PMID: 23436470 DOI: 10.1002/chem.201203396] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Indexed: 11/07/2022]
Abstract
The discovery and elucidation of a new Nazarov cyclization/Wagner-Meerwein rearrangement/oxidation sequence is described that constitutes an efficient strategy for the synthesis of 4-alkylidene cyclopentenones. DFT computations and EPR experiments were conducted to gain further mechanistic insight into the reaction pathways.
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Affiliation(s)
- David Lebœuf
- Department of Chemistry, University of Rochester, Rochester, NY 14627, USA
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24
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Lebœuf D, Wright CM, Frontier AJ. Reagent Control of [1,2]-Wagner-Meerwein Shift Chemoselectivity Following the Nazarov Cyclization: Application to the Total Synthesis of Enokipodin B. Chemistry 2013; 19:4835-41. [PMID: 23436444 DOI: 10.1002/chem.201203395] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 11/26/2012] [Indexed: 02/05/2023]
Affiliation(s)
- David Lebœuf
- Department of Chemistry, University of Rochester, Rochester, NY 14627, USA
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25
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Lebœuf D, Gandon V, Ciesielski J, Frontier AJ. Experimental and theoretical studies on the Nazarov cyclization/Wagner-Meerwein rearrangement sequence. J Am Chem Soc 2012; 134:6296-308. [PMID: 22471833 PMCID: PMC3382077 DOI: 10.1021/ja211970p] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Highly functionalized cyclopentenones can be generated by a chemoselective copper(II)-mediated Nazarov/Wagner-Meerwein rearrangement sequence of divinyl ketones. A detailed investigation of this sequence is described including a study of substrate scope and limitations. After the initial 4π electrocyclization, this reaction proceeds via two different sequential [1,2]-shifts, with selectivity that depends upon either migratory ability or the steric bulkiness of the substituents at C1 and C5. This methodology allows the creation of vicinal stereogenic centers, including adjacent quaternary centers. This sequence can also be achieved by using a catalytic amount of copper(II) in combination with NaBAr(4)(f), a weak Lewis acid. During the study of the scope of the reaction, a partial or complete E/Z isomerization of the enone moiety was observed in some cases prior to the cyclization, which resulted in a mixture of diastereomeric products. Use of a Cu(II)-bisoxazoline complex prevented the isomerization, allowing high diastereoselectivity to be obtained in all substrate types. In addition, the reaction sequence was studied by DFT computations at the UB3LYP/6-31G(d,p) level, which are consistent with the proposed sequences observed, including E/Z isomerizations and chemoselective Wagner-Meerwein shifts.
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Affiliation(s)
- David Lebœuf
- Department of Chemistry, University of Rochester, Rochester, NY 14627
| | - Vincent Gandon
- ICMMO, UMR CNRS 8182, Université Paris-Sud 11, 91405 Orsay cedex, France
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26
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Tang Q, Chen X, Tiwari B, Chi YR. Addition of indoles to oxyallyl cations for facile access to α-indole carbonyl compounds. Org Lett 2012; 14:1922-5. [PMID: 22455439 DOI: 10.1021/ol300591z] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A direct coupling of unprotected indoles and α-halo ketones via in situ generated oxyallyl cation intermediates is described. The reactions efficiently afford α-indole carbonyl compounds with good to quantitative yields.
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Affiliation(s)
- Qiang Tang
- Division of Chemistry & Biological Chemistry, School of Physical & Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
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27
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Malona JA, Cariou K, Spencer WT, Frontier AJ. Total synthesis of (±)-rocaglamide via oxidation-initiated Nazarov cyclization. J Org Chem 2012; 77:1891-908. [PMID: 22283818 DOI: 10.1021/jo202366c] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
This article describes the evolution of a Nazarov cyclization-based synthetic strategy targeting the anticancer, antiinflammatory, and insecticidal natural product (±)-rocaglamide. Initial pursuit of a polarized heteroaromatic Nazarov cyclization to construct the congested cyclopentane core revealed an unanticipated electronic bias in the pentadienyl cation. This reactivity was harnessed in a successful second-generation approach using an oxidation-initiated Nazarov cyclization of a heteroaryl alkoxyallene. Full details of these two approaches are given, as well as the characterization of undesired reaction pathways available to the Nazarov cyclization product. A sequence of experiments that led to an understanding of the unexpected reactivity of this key intermediate is described, which culminated in the successful total synthesis of (+)-rocaglamide.
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Affiliation(s)
- John A Malona
- Department of Chemistry, University of Rochester, Rochester, New York 14627, USA
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28
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Boudreau J, Courtemanche MA, Marx VM, Jean Burnell D, Fontaine FG. Ambiphilic molecules for trapping reactive intermediates: interrupted Nazarov reaction of allenyl vinyl ketones with Me2PCH2AlMe2. Chem Commun (Camb) 2012; 48:11250-2. [DOI: 10.1039/c2cc35257e] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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29
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Wu YK, McDonald R, West FG. Homologous Mukaiyama Reactions via Trapping of the Nazarov Intermediate with Silyloxyalkenes. Org Lett 2011; 13:3584-7. [DOI: 10.1021/ol201125h] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yen-Ku Wu
- Department of Chemistry, University of Alberta, E3-43 Gunning-Lemieux Chemistry Centre, Edmonton, AB T6G 2G2, Canada
| | - Robert McDonald
- Department of Chemistry, University of Alberta, E3-43 Gunning-Lemieux Chemistry Centre, Edmonton, AB T6G 2G2, Canada
| | - F. G. West
- Department of Chemistry, University of Alberta, E3-43 Gunning-Lemieux Chemistry Centre, Edmonton, AB T6G 2G2, Canada
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Marx VM, Stoddard RL, Heverly-Coulson GS, Burnell DJ. Substituent-Controlled Reactivity in the Nazarov Cyclisation of Allenyl Vinyl Ketones. Chemistry 2011; 17:8098-104. [DOI: 10.1002/chem.201100519] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Indexed: 11/06/2022]
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Marx VM, LeFort FM, Burnell DJ. Trapping the Oxyallyl Cation Intermediate Derived from the Nazarov Cyclization of Allenyl Vinyl Ketones with Nitrogen Heterocycles. Adv Synth Catal 2010. [DOI: 10.1002/adsc.201000722] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Affiliation(s)
- Yen-Ku Wu
- Department of Chemistry, University of Alberta, E3-43 Gunning-Lemieux Chemistry Centre, Edmonton, AB, Canada T6G 2G2
| | - F. G. West
- Department of Chemistry, University of Alberta, E3-43 Gunning-Lemieux Chemistry Centre, Edmonton, AB, Canada T6G 2G2
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Marx VM, Burnell DJ. Nazarov cyclizations of an allenyl vinyl ketone with interception of the oxyallyl cation intermediate for the formation of carbon-carbon bonds. J Am Chem Soc 2010; 132:1685-9. [PMID: 20078119 DOI: 10.1021/ja909073r] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Treatment of an allenyl vinyl ketone with BF(3) x Et(2)O leads to a cyclic oxyallyl cation by a Nazarov reaction, and when this reaction is conducted in the presence of an acyclic diene, [4 + 3] and [3 + 2] products are obtained efficiently with high regio- and stereoselectivity. The proportion of [4 + 3] to [3 + 2] product depends on the substitution on the diene. Cyclic dienes react with the oxyallyl cation by forming only one carbon-carbon bond, but the site of bond formation can be affected by steric hindrance. Electron-rich alkenes intercept the allyl cation by forming one carbon-carbon bond, or two carbon-carbon bonds through [3 + 2] cyclization. In some instances, further treatment of the initial products with BF(3) x Et(2)O leads to equilibrated products in good yield.
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Affiliation(s)
- Vanessa M Marx
- Department of Chemistry, Dalhousie University, Halifax, Nova Scotia B3H 4J3, Canada
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