1
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Liu Y, Zhao J, Hong R. Toward the Briarane Core via 1,3-Dipolar Cycloaddition. Org Lett 2024. [PMID: 38804559 DOI: 10.1021/acs.orglett.4c01411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
The complete C20 framework of brianthein W was established, featuring hydroboration/allylation, to provide the C1-C2 quaternary/tertiary stereoarray with excellent stereocontrol. Intramolecular nitrile oxide cycloaddition (INOC) was adopted as the key transformation to establish the trans-fused 6/10-bicyclic ring system. Evolution of the second INOC event revealed the intricacies governing regioselectivity, which ultimately led to construction of the highly strained 10-membered carbocycle.
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Affiliation(s)
- Yichen Liu
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, P.R. China
- University of Chinese Academy of Sciences, Beijing 101408, P.R. China
| | - Jiangang Zhao
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, P.R. China
- University of Chinese Academy of Sciences, Beijing 101408, P.R. China
| | - Ran Hong
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, P.R. China
- University of Chinese Academy of Sciences, Beijing 101408, P.R. China
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2
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Witt CH, Woerpel KA. Diastereoselective Alkylations of Chiral Tetrazolo[1,5- a]azepines via Heterobenzylic Anion Intermediates. Org Lett 2022; 24:6722-6727. [PMID: 36095147 PMCID: PMC9850863 DOI: 10.1021/acs.orglett.2c02445] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The alkylations of chiral seven-membered rings fused to tetrazoles are highly diastereoselective. The diastereoselectivity depended on the placement and the size of the substituent on the ring and on the electrophile. Subsequent alkylations occurred with high stereoselectivity, allowing for the construction of quaternary stereocenters. Computational studies revealed that torsional effects are responsible for the observed diastereoselectivities. Substituted products can be reduced to the corresponding secondary amines, thus providing an approach for synthesizing diastereomerically enriched azepanes.
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Affiliation(s)
- Collin H. Witt
- Department of Chemistry, New York University, 100 Washington Square East, New York, NY 10003, United States
| | - K. A. Woerpel
- Department of Chemistry, New York University, 100 Washington Square East, New York, NY 10003, United States
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3
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Sabot C, Mabrouki A, Le Nahenec-Martel P, Kriaa A, Hedhli A, Renard PY. Dearomatization of a 3-Hydroxypyridine Through an Unexpected Oxidative Deformylation Process: An Entry to Azacyclohexadienones. Synlett 2020. [DOI: 10.1055/s-0040-1706870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Phenols are well-known precursors of cyclohexadienones, which have widespread applications in organic synthesis. In contrast, their hydroxypyridine counterparts have not been explored yet. An unprecedented oxidative dearomatization of a 3-hydroxypyridine involving an unexpected deformylation step is reported. The chemical reactivity of the resulting unreported azacyclohexadiene-type compound was also explored.
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Affiliation(s)
- Cyrille Sabot
- Normandie Univ, CNRS, UNIROUEN, INSA Rouen, COBRA (UMR 6014)
| | - Afef Mabrouki
- Laboratory of Molecular Organic Chemistry, National Higher Engineering School of Tunis
| | | | - Abdelkader Kriaa
- Laboratory of Molecular Organic Chemistry, National Higher Engineering School of Tunis
| | - Ahmed Hedhli
- Laboratory of Molecular Organic Chemistry, National Higher Engineering School of Tunis
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4
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Csókás D, Siitonen JH, Pihko PM, Pápai I. Conformationally Locked Pyramidality Explains the Diastereoselectivity in the Methylation of trans-Fused Butyrolactones. Org Lett 2020; 22:4597-4601. [PMID: 32338517 PMCID: PMC7309317 DOI: 10.1021/acs.orglett.0c01008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
![]()
A stereoselectivity
model inspired by the total synthesis of stemona
alkaloids is developed to explain why enolate-derived 3,4-fused butyrolactones
are methylated with a preference for syn alkylation.
The model shows how conformational locking present in nonplanar enolate
structures favors syn over anti methylation,
due to less significant structural distortions in the syn pathway. The developed model was also successfully used to rationalize
selectivities of previously documented methylation reactions.
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Affiliation(s)
- Dániel Csókás
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Magyar tudósok körútja 2, H-1117 Budapest, Hungary
| | - Juha H Siitonen
- Department of Chemistry, Nanoscience Centre, University of Jyväskylä, P.O. Box 35, FI-40014 Jyväskylä, Finland
| | - Petri M Pihko
- Department of Chemistry, Nanoscience Centre, University of Jyväskylä, P.O. Box 35, FI-40014 Jyväskylä, Finland
| | - Imre Pápai
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Magyar tudósok körútja 2, H-1117 Budapest, Hungary
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5
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Huynh TH, Lee GH, Fang LS, Sheu JH, Sung PJ. Briarenols F–H: New polyoxygenated briarane diterpenoids produced by the octocoral Briareum excavatum. Tetrahedron Lett 2020. [DOI: 10.1016/j.tetlet.2020.151826] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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6
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Sung PJ, Hwang TL, Wu YC, Chen YH, Chin HK, Peng BR, Chen YY, Hu CC, Zheng LG, Huynh TH, Su TP, Zhang YL, Wen ZH. Survey of Briarane-Type Diterpenoids – Part VII. HETEROCYCLES 2020. [DOI: 10.3987/rev-19-925] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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7
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Tang T, Moon NG, McKay L, Harned AM. New Strategy To Access Enantioenriched Cyclohexadienones: Kinetic Resolution of para-Quinols by Organocatalytic Thiol-Michael Addition Reactions. ACS OMEGA 2018; 3:15492-15500. [PMID: 31458205 PMCID: PMC6643461 DOI: 10.1021/acsomega.8b01787] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 10/31/2018] [Indexed: 06/10/2023]
Abstract
Existing stereoselective routes to 2,5-cyclohexadienones involve either desymmetrization of an achiral substrate or have attempted to perform an asymmetric dearomatization of a phenol. Herein, we report proof-of-principle experiments aimed at developing a kinetic resolution as an alternative method for accessing enantioenriched 2,5-cyclohexadienones. More specifically, chiral bifunctional thiourea catalysts were used to promote the addition of 2-thionapthalene into unsymmetric para-quinols. The selectivity of the kinetic resolution was found to be quite sensitive to substitution around the substrate.
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Affiliation(s)
- Ting Tang
- Department
of Chemistry & Biochemistry, Texas Tech
University, 1204 Boston Avenue, Lubbock, Texas 79409-1061, United States
| | - Nicholas G. Moon
- Department
of Chemistry, University of Minnesota—Twin
Cities, 207 Pleasant
Street SE, Minneapolis, Minnesota 55455, United States
| | - Lydia McKay
- Department
of Chemistry & Biochemistry, Texas Tech
University, 1204 Boston Avenue, Lubbock, Texas 79409-1061, United States
| | - Andrew. M. Harned
- Department
of Chemistry & Biochemistry, Texas Tech
University, 1204 Boston Avenue, Lubbock, Texas 79409-1061, United States
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8
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Moon NG, Harned AM. Synthetic explorations of the briarane jungle: progress in developing a synthetic route to a common family of diterpenoid natural products. ROYAL SOCIETY OPEN SCIENCE 2018; 5:172280. [PMID: 29892413 PMCID: PMC5990800 DOI: 10.1098/rsos.172280] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 04/11/2018] [Indexed: 05/08/2023]
Abstract
The briarane diterpenoids are a large family of marine natural products that have been primarily isolated from gorgonian octocorals around the world. Structurally, the family is characterized by a trans-fused bicyclo[8.4.0]tetradecane ring system containing a central, stereogenic, all-carbon quaternary carbon (C1) flanked by three additional stereocentres (C2, C10, C14). Many family members have demonstrated biological activity in numerous areas, including: cytotoxicity, anti-inflammatory, antiviral, antifungal, immunomodulatory and insect control. Despite their interesting structural properties and bioactivity, the briaranes have been largely overlooked by the synthetic community. However, in recent years, several research groups have reported progress toward developing a synthetic route to these natural products. Most of these efforts have focused on the stereoselective construction of the central C1-C2-C10-C14 stereotetrad. This review will discuss the various synthetic efforts aimed at the briarane diterpenoids along with the challenges that remain.
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Affiliation(s)
- Nicholas G. Moon
- Department of Chemistry, University of Minnesota—Twin Cities, 207 Pleasant Street SE, Minneapolis, MN 55455, USA
| | - Andrew M. Harned
- Department of Chemistry and Biochemistry, Texas Tech University, 1204 Boston Avenue, Lubbock, TX 79409-1061, USA
- Author for correspondence: Andrew M. Harned e-mail:
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9
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Crimmins MT, Zhang Y, Williams PS. Approach to the Synthesis of Briarane Diterpenes through a Dianionic Claisen Rearrangement and Ring-Closing Metathesis. Org Lett 2017; 19:3907-3910. [DOI: 10.1021/acs.orglett.7b01806] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Michael T. Crimmins
- Kenan, Caudill, Venable,
and Murray Laboratories of Chemistry University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Yan Zhang
- Kenan, Caudill, Venable,
and Murray Laboratories of Chemistry University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Philip S. Williams
- Kenan, Caudill, Venable,
and Murray Laboratories of Chemistry University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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