1
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Mamada S, Ogawa N. Regioselective Alkynylation of Allylic Phosphates with Alkynyl Copper Reagents. European J Org Chem 2023. [DOI: 10.1002/ejoc.202300056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
Affiliation(s)
- Shunki Mamada
- Department of Applied Chemistry Meiji University 1-1-1 Higashimita, Tama-ku 214-8571 Kawasaki Kanagawa Japan
| | - Narihito Ogawa
- Department of Applied Chemistry Meiji University 1-1-1 Higashimita, Tama-ku 214-8571 Kawasaki Kanagawa Japan
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2
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Johny M, Philip RM, Rajendar G. Highly Regio- and Stereoselective Intramolecular Rearrangement of Glycidol Acetal to Alkoxy Cyclic Acetals. Org Lett 2022; 24:6165-6170. [PMID: 35960602 DOI: 10.1021/acs.orglett.2c02397] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new class of highly regio- and stereoselective intramolecular rearrangements of glycidol acetals to produce alkoxylated 1,3-dioxolane/1,3-dioxane is demonstrated. Selective Lewis acid activation of acetal generates an oxocarbenium ion that initiates the epoxide ring-opening event, giving the bicyclic [3,1,0]epoxonium ion intermediate that undergoes exo/endo-selective opening by a tethered alkoxide. Mechanistic insights into preferential acetal activation over the epoxide were obtained by crossover experiments. The method was applied in the total synthesis of parvistone B and its 8-ethoxy analogue.
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Affiliation(s)
- Meera Johny
- School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, India 695551
| | - Rose Mary Philip
- School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, India 695551
| | - Goreti Rajendar
- School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, India 695551
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3
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Chan HSS, Thompson AL, Christensen KE, Burton JW. Forwards and backwards - synthesis of Laurencia natural products using a biomimetic and retrobiomimetic strategy incorporating structural reassignment of laurefurenynes C-F. Chem Sci 2020; 11:11592-11600. [PMID: 34094406 PMCID: PMC8162873 DOI: 10.1039/d0sc04120c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 09/25/2020] [Indexed: 11/26/2022] Open
Abstract
Laurefurenynes C-F are four natural products isolated from Laurencia species whose structures were originally determined on the basis of extensive nuclear magnetic resonance experiments. On the basis of a proposed biogenesis, involving a tricyclic oxonium ion as a key intermediate, we have reassigned the structures of these four natural products and synthesized the four reassigned structures using a biomimetic approach demonstrating that they are the actual structures of the natural products. In addition, we have developed a synthesis of the enantiomers of the natural products laurencin and deacetyllaurencin from the enantiomer of (E)-laurefucin using an unusual retrobiomimetic strategy. All of these syntheses have been enabled by the use of tricyclic oxonium ions as pivotal synthetic intermediates.
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Affiliation(s)
- Hau Sun Sam Chan
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford Mansfield Road Oxford OX1 3TA UK
| | - Amber L Thompson
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford Mansfield Road Oxford OX1 3TA UK
| | - Kirsten E Christensen
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford Mansfield Road Oxford OX1 3TA UK
| | - Jonathan W Burton
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford Mansfield Road Oxford OX1 3TA UK
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4
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Taylor CA, Zhang YA, Snyder SA. The enantioselective total synthesis of laurendecumallene B. Chem Sci 2020; 11:3036-3041. [PMID: 34122807 PMCID: PMC8157515 DOI: 10.1039/c9sc06116a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 02/05/2020] [Indexed: 02/04/2023] Open
Abstract
For decades, the Laurencia family of halogenated C15-acetogenins has served as a valuable testing ground for the prowess of chemical synthesis, particularly as it relates to generating functionalized 8-membered bromoethers. Herein, we show that a readily modified and predictable approach that generates such rings and an array of attendant stereocenters via a bromenium-induced cyclization/ring-expansion process can be used to synthesize laurendecumallene B and determine the configuration of two of its previously unassigned stereocenters. In particular, this work highlights how the use of the bromenium source BDSB (Et2SBr·SbCl5Br) in non-conventional solvents is essential in generating much of the target's complexity in optimal yields and stereoselectivity. Moreover, the final structural assignment of laurendecumallene B reveals that it has one element of bromine-based chirality that, to the best of our knowledge, is not shared with any other member of the class.
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Affiliation(s)
- Cooper A Taylor
- Department of Chemistry, University of Chicago 5735 S. Ellis Avenue Chicago IL 60637 USA
| | - Yu-An Zhang
- Department of Chemistry, University of Chicago 5735 S. Ellis Avenue Chicago IL 60637 USA
| | - Scott A Snyder
- Department of Chemistry, University of Chicago 5735 S. Ellis Avenue Chicago IL 60637 USA
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5
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Sam Chan HS, Nguyen QNN, Paton RS, Burton JW. Synthesis, Characterization, and Reactivity of Complex Tricyclic Oxonium Ions, Proposed Intermediates in Natural Product Biosynthesis. J Am Chem Soc 2019; 141:15951-15962. [PMID: 31560524 DOI: 10.1021/jacs.9b07438] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Reactive intermediates frequently play significant roles in the biosynthesis of numerous classes of natural products although the direct observation of these biosynthetically relevant species is rare. We present here direct evidence for the existence of complex, thermally unstable, tricyclic oxonium ions that have been postulated as key reactive intermediates in the biosynthesis of numerous halogenated natural products from Laurencia species. Evidence for their existence comes from full characterization of these oxonium ions by low-temperature NMR spectroscopy supported by density functional theory (DFT) calculations, coupled with the direct generation of 10 natural products on exposure of the oxonium ions to various nucleophiles.
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Affiliation(s)
- Hau Sun Sam Chan
- Chemistry Research Laboratory , University of Oxford , Mansfield Road , Oxford OX1 3TA , U.K
| | - Q Nhu N Nguyen
- Chemistry Research Laboratory , University of Oxford , Mansfield Road , Oxford OX1 3TA , U.K
| | - Robert S Paton
- Chemistry Research Laboratory , University of Oxford , Mansfield Road , Oxford OX1 3TA , U.K.,Department of Chemistry , Colorado State University , Fort Collins , Colorado 80523 , United States
| | - Jonathan W Burton
- Chemistry Research Laboratory , University of Oxford , Mansfield Road , Oxford OX1 3TA , U.K
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6
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Zhang YA, Yaw N, Snyder SA. General Synthetic Approach for the Laurencia Family of Natural Products Empowered by a Potentially Biomimetic Ring Expansion. J Am Chem Soc 2019; 141:7776-7788. [DOI: 10.1021/jacs.9b01088] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Yu-An Zhang
- Department of Chemistry, University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, United States
| | - Natalie Yaw
- Department of Chemistry, University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, United States
| | - Scott A. Snyder
- Department of Chemistry, University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, United States
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7
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Brown ZJ, Fu Q, Ma C, Kruhlak M, Zhang H, Luo J, Heinrich B, Yu SJ, Zhang Q, Wilson A, Shi ZD, Swenson R, Greten TF. Carnitine palmitoyltransferase gene upregulation by linoleic acid induces CD4 + T cell apoptosis promoting HCC development. Cell Death Dis 2018; 9:620. [PMID: 29795111 PMCID: PMC5966464 DOI: 10.1038/s41419-018-0687-6] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 03/29/2018] [Accepted: 05/04/2018] [Indexed: 12/19/2022]
Abstract
Hepatocellular carcinoma (HCC) is a common cause of cancer-related death worldwide. As obesity and diabetes become more prevalent, the contribution of non-alcoholic fatty liver disease (NAFLD) to HCC is rising. Recently, we reported intrahepatic CD4+ T cells are critical for anti-tumor surveillance in NAFLD. Lipid accumulation in the liver is the hallmark of NAFLD, which may perturb T cell function. We sought to investigate how the lipid-rich liver environment influences CD4+ T cells by focusing on carnitine palmitoyltransferase (CPT) family members, which control the mitochondrial β-oxidation of fatty acids and act as key molecules in lipid catabolism. Linoleic acid (C18:2) co-localized within the mitochondria along with a corresponding increase in CPT gene upregulation. This CPT upregulation can be recapitulated by feeding mice with a high-C18:2 diet or the NAFLD promoting methionine-choline-deficient (MCD) diet. Using an agonist and antagonist, the induction of CPT genes was found to be mediated by peroxisome proliferator-activated receptor alpha (PPAR-α). CPT gene upregulation increased mitochondrial reactive oxygen species (ROS) and led to cell apoptosis. In vivo, using liver-specific inducible MYC transgenic mice fed MCD diet, blocking CPT with the pharmacological inhibitor perhexiline decreased apoptosis of intrahepatic CD4+ T cells and inhibited HCC tumor formation. These results provide useful information for potentially targeting the CPT family to rescue intrahepatic CD4+ T cells and to aid immunotherapy for NAFLD-promoted HCC.
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Affiliation(s)
- Zachary J Brown
- Gastrointestinal Malignancy Section, Thoracic and Gastrointestinal Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Qiong Fu
- Gastrointestinal Malignancy Section, Thoracic and Gastrointestinal Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Chi Ma
- Gastrointestinal Malignancy Section, Thoracic and Gastrointestinal Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Michael Kruhlak
- Experimental Immunology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Haibo Zhang
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Ji Luo
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Bernd Heinrich
- Gastrointestinal Malignancy Section, Thoracic and Gastrointestinal Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Su Jong Yu
- Gastrointestinal Malignancy Section, Thoracic and Gastrointestinal Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA.,Department of Internal Medicine and Liver Research Institute, Seoul National University College of Medicine, Seoul, Korea
| | - Qianfei Zhang
- Gastrointestinal Malignancy Section, Thoracic and Gastrointestinal Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Andrew Wilson
- Gastrointestinal Malignancy Section, Thoracic and Gastrointestinal Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Zhen-Dan Shi
- Imaging Probe Development Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Rolf Swenson
- Imaging Probe Development Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Tim F Greten
- Gastrointestinal Malignancy Section, Thoracic and Gastrointestinal Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
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8
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Pinnatifidenyne-Derived Ethynyl Oxirane Acetogenins from Laurencia viridis. Mar Drugs 2017; 16:md16010005. [PMID: 29286293 PMCID: PMC5793053 DOI: 10.3390/md16010005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 12/05/2017] [Accepted: 12/13/2017] [Indexed: 01/03/2023] Open
Abstract
Red algae of Laurencia continue to provide wide structural diversity and complexity of halogenated C15 acetogenin medium-ring ethers. Here, we described the isolation of three new C15 acetogenins (3–5), and one truncated derivative (6) from Laurencia viridis collected on the Canary Islands. These compounds are interesting variations on the pinnatifidenyne structure that included the first examples of ethynyl oxirane derivatives (3–4). The structures were elucidated by extensive study of NMR (Nuclear Magnetic Resonance) data, J-based configuration analysis and DFT (Density Functional Theory) calculations. Their antiproliferative activity against six human solid tumor cell lines was evaluated.
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9
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Ahn J, Lim C, Yun H, Kim HS, Kwon S, Lee J, Lee S, An H, Park HG, Suh YG. Asymmetric Total Synthesis of (+)-Intricenyne via an Endocyclization Route to Oxocane Skeleton. Org Lett 2017; 19:6642-6645. [DOI: 10.1021/acs.orglett.7b03370] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jungmin Ahn
- Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Changjin Lim
- Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
- College
of Pharmacy, CHA University, 120 Haeryong-ro, Pocheon, Gyeonggi-do 11160, Republic of Korea
| | - Hwayoung Yun
- College
of Pharmacy, Pusan National University, Busan 46241, Republic of Korea
| | - Hyun Su Kim
- Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Soonbum Kwon
- Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Jeeyeon Lee
- Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Seungbeom Lee
- Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Hongchan An
- Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Hyeong-geun Park
- Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Young-Ger Suh
- Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
- College
of Pharmacy, CHA University, 120 Haeryong-ro, Pocheon, Gyeonggi-do 11160, Republic of Korea
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10
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Clarke J, Bonney KJ, Yaqoob M, Solanki S, Rzepa HS, White AJP, Millan DS, Braddock DC. Epimeric Face-Selective Oxidations and Diastereodivergent Transannular Oxonium Ion Formation Fragmentations: Computational Modeling and Total Syntheses of 12-Epoxyobtusallene IV, 12-Epoxyobtusallene II, Obtusallene X, Marilzabicycloallene C, and Marilzabicycloallene D. J Org Chem 2016; 81:9539-9552. [PMID: 27704814 DOI: 10.1021/acs.joc.6b02008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The total syntheses of 12-epoxyobtusallene IV, 12-epoxyobtusallene II, obtusallene X, marilzabicycloallene C, and marilzabicycloallene D as halogenated C15-acetogenin 12-membered bicyclic and tricyclic ether bromoallene-containing marine metabolites from Laurencia species are described. Two enantiomerically pure C4-epimeric dioxabicyclo[8.2.1]tridecenes were synthesized by E-selective ring-closing metathesis where their absolute stereochemistry was previously set via catalytic asymmetric homoallylic epoxidation and elaborated via regioselective epoxide-ring opening and diastereoselective bromoetherification. Epimeric face-selective oxidation of their Δ12,13 olefins followed by bromoallene installation allowed access to the oppositely configured 12,13-epoxides of 12-epoxyobtusallene II and 12-epoxyobtusallene IV. Subsequent exploration of their putative biomimetic oxonium ion formation-fragmentations reactions revealed diastereodivergent pathways giving marilzabicycloallene C and obtusallene X, respectively. The original configurations of the substrates evidently control oxonium ion formation and their subsequent preferred mode of fragmentation by nucleophilic attack at C9 or C12. Quantum modeling of this stereoselectivity at the ωB97X-D/Def2-TZVPPD/SCRF = methanol level revealed that in addition to direction resulting from hydrogen bonding, the dipole moment of the ion-pair transition state is an important factor. Marilzabicycloallene D as a pentahalogenated 12-membered bicyclic ether bromoallene was synthesized by a face-selective chloronium ion initiated oxonium ion formation-fragmentation process followed by subsequent bromoallene installation.
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Affiliation(s)
- James Clarke
- Department of Chemistry, Imperial College London , South Kensington, London, SW7 2AZ, U.K
| | - Karl J Bonney
- Department of Chemistry, Imperial College London , South Kensington, London, SW7 2AZ, U.K
| | - Muhammad Yaqoob
- Department of Chemistry, Imperial College London , South Kensington, London, SW7 2AZ, U.K
| | - Savade Solanki
- Department of Chemistry, Imperial College London , South Kensington, London, SW7 2AZ, U.K
| | - Henry S Rzepa
- Department of Chemistry, Imperial College London , South Kensington, London, SW7 2AZ, U.K
| | - Andrew J P White
- Department of Chemistry, Imperial College London , South Kensington, London, SW7 2AZ, U.K
| | - David S Millan
- Sandwich Laboratories, Pfizer Global Research and Development, Ramsgate Road, Sandwich, Kent CT13 9NJ, U.K
| | - D Christopher Braddock
- Department of Chemistry, Imperial College London , South Kensington, London, SW7 2AZ, U.K
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11
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Saska J, Lewis W, Paton RS, Denton RM. Synthesis of malhamensilipin A exploiting iterative epoxidation/chlorination: experimental and computational analysis of epoxide-derived chloronium ions. Chem Sci 2016; 7:7040-7049. [PMID: 28337338 PMCID: PMC5282550 DOI: 10.1039/c6sc03012b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 08/02/2016] [Indexed: 11/21/2022] Open
Abstract
We report a 12-step catalytic enantioselective formal synthesis of malhamensilipin A (3) based upon an iterative epoxidation/chlorination strategy.
We report a 12-step catalytic enantioselective formal synthesis of malhamensilipin A (3) and diastereoisomeric analogues from (E)-2-undecenal. The convergent synthesis relied upon iterative epoxidation and phosphorus(v)-mediated deoxydichlorination reactions as well a titanium-mediated epoxide-opening to construct the C11–C16 stereohexad. The latter transformation occurred with very high levels of stereoretention regardless of the C13 configuration of the parent epoxide, implicating anchimeric assistance of either the γ- or δ-chlorine atoms, and the formation of chloretanium or chlorolanium ions, respectively. A computational analysis of the chloronium ion intermediates provided support for the involvement of chlorolanium ions, whereas the potential chloretanium ions were found to be less likely intermediates on the basis of their greater carbocationic character.
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Affiliation(s)
- J Saska
- School of Chemistry , University Park , Nottingham , NG7 2RD , UK .
| | - W Lewis
- School of Chemistry , University Park , Nottingham , NG7 2RD , UK .
| | - R S Paton
- Chemistry Research Laboratory , 12 Mansfield Road , Oxford OX1 3TA , UK .
| | - R M Denton
- School of Chemistry , University Park , Nottingham , NG7 2RD , UK .
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12
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Taylor MT, Fox JM. Biosynthesis of the C15-acetogenin laurepoxide may involve bromine-induced skeletal rearrangement of a Δ4-oxocene precursor. Tetrahedron Lett 2015; 56:3560-3563. [PMID: 26146420 DOI: 10.1016/j.tetlet.2015.03.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An electrophilic bromine catalyzed skeletal rearrangement of an Δ4-oxocene to an epoxy furan has been described. This skeletal rearrangement suggests a plausible mechanism for the biosynthesis of the C15-acetogenin laurepoxide.
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Affiliation(s)
- Michael T Taylor
- Brown Laboratories, Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Joseph M Fox
- Brown Laboratories, Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
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