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Liu L, Du L, Li B. Recent advances in 8π electrocyclization reactions. Chem Commun (Camb) 2023; 59:670-687. [PMID: 36597987 DOI: 10.1039/d2cc04805a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Medium-ring systems, which constitute a class of structurally intriguing and biologically important molecules, are present in many natural products and pharmaceuticals. However, the construction of these skeletons tends to be difficult because of the torsional strain of the medium-sized ring, and control of the selectivity is also challenging in these flexible skeletons. Electrocyclization is one of the most straightforward methods to construct medium-sized rings and this process typically proceeds in a stereospecific manner, resulting in the stereo-controlled formation of two neighboring stereocenters. At present, there are few studies on 8π electrocyclization, mainly focusing on the synthesis of small molecules, while the applications in the synthesis of functional materials and biological contexts are rare. This feature article highlights recent advances, from 2000 to 2022, in the 8π electrocyclization reaction. This study is organized into four sections based on the size/composition of the target ring, including the synthesis of aza-seven-membered, cycloheptene, cyclooctene and bicyclo[4,2,0]octane frameworks. We expect that this feature article will provide beneficial guidance for the selective construction of medium-ring skeletons.
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Affiliation(s)
- Lei Liu
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 400044, China.
| | - Luan Du
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 400044, China.
| | - Baosheng Li
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 400044, China.
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Guo R, Witherspoon BP, Brown MK. Stereoselective [2+2]-Cycloadditions of chiral allenic ketones and alkenes: Applications towards the synthesis of benzocyclobutenes and endiandric acids. Tetrahedron 2022; 122:132932. [PMID: 36685046 PMCID: PMC9850822 DOI: 10.1016/j.tet.2022.132932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Cyclobutanes are important motifs that have found utility in many contexts. Prior work has demonstrated an enantioselective isomerization/stereoselective [2 + 2] as a means to access bicyclo [4.2.0] octanes. Herein, the utility of this method is demonstrated towards the synthesis of benzocyclobutenes and a key intermediate towards the endiandric acids.
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Affiliation(s)
| | | | - M. Kevin Brown
- Indiana University, Department of Chemistry, 800 E. Kirkwood Ave., Bloomington, IN, 47405, USA
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Patel HD, Fallon T. Two Steps to Bicyclo[4.2.0]octadienes from Cyclooctatetraene: Total Synthesis of Kingianic Acid A. Org Lett 2022; 24:2276-2281. [PMID: 35293754 DOI: 10.1021/acs.orglett.2c00325] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Synthetic approaches to bicyclo[4.2.0]octadiene natural products frequently employ the synthesis of linear tetraenes to initiate a biosynthetic 8π/6π-electrocyclization cascade. This work forges a functionalized bicyclo[4.2.0]octadiene in two steps from cyclooctatetraene. The versatility of this method is demonstrated through natural product synthesis, including the first total synthesis of kingianic acid A and formal syntheses of kingianins A, D, and F and cryptobeilic acid D ethyl ester. The unexpected formation of an E,E,Z,E-tetraene byproduct is rationalized through density functional theory modeling.
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Affiliation(s)
- Harshal D Patel
- Department of Chemistry, The University of Adelaide, Adelaide, SA 5005 (Australia)
| | - Thomas Fallon
- Department of Chemistry, The University of Adelaide, Adelaide, SA 5005 (Australia)
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Yahiaoui O, Almass A, Fallon T. Total synthesis of endiandric acid J and beilcyclone A from cyclooctatetraene. Chem Sci 2020; 11:9421-9425. [PMID: 34094208 PMCID: PMC8161681 DOI: 10.1039/d0sc03073b] [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: 06/01/2020] [Accepted: 07/16/2020] [Indexed: 12/25/2022] Open
Abstract
The endiandric acids are classic targets in natural product synthesis. The spectacular 8π/6π-electrocylisation/intramolecular Diels-Alder (8π/6π/IMDA) reaction cascade at the heart of their biosynthesis has inspired practitioners and students of pericyclic chemistry for nearly forty years. All previous synthetic approaches have sought to prepare a linear tetraene and thereby initiate the cascade. In this communication we demonstrate the use of cyclooctatetraene to rapidly intercept the 8π/6π/IMDA cascade at the cyclooctatriene stage. Endiandric acid J and beilcyclone A are prepared for the first time in six and five steps, respectively. The strategy features a tactical overall anti-vicinal difunctionalisation of cyclooctatetraene through SN2' alkylation of cyclooctatetraene oxide followed by an intriguing tandem Claisen rearrangement/6π-electrocyclisation from the corresponding vinyl ether. This rapidly constructs an advanced bicyclo[4.2.0]octadiene aldehyde intermediate. Olefinations and intramolecular Diels-Alder cycloadditions complete the syntheses. This establishes a short and efficient new path to the endiandric acid natural products. DFT modelling predicts thermal racemisation of bicyclo[4.2.0]octadiene intermediates, dashing hopes of enantioselective synthesis.
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Affiliation(s)
- Oussama Yahiaoui
- Department of Chemistry, The University of Adelaide Adelaide SA 5005 Australia
| | - Adrian Almass
- Department of Chemistry, The University of Adelaide Adelaide SA 5005 Australia
| | - Thomas Fallon
- Department of Chemistry, The University of Adelaide Adelaide SA 5005 Australia
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Ma D, Liu Y, Wang Z. Biomimetic Total Synthesis of (±)-Homodimericin A. Angew Chem Int Ed Engl 2017; 56:7886-7889. [PMID: 28494121 DOI: 10.1002/anie.201702775] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Indexed: 11/12/2022]
Abstract
A biomimetic total synthesis of racemic homodimericin A was achieved in seven steps, including two cascade reactions. Aqueous buffer solutions are found to help both the oxidative dimerization cascade and the intramolecular Diels-Alder cascade. This synthetic sequence validates key steps in the biogenetic proposal of homodimericin A.
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Affiliation(s)
- Donghui Ma
- Department of Chemistry, University at Albany, State University of New York, 1400 Washington Ave. CH232, Albany, NY, 12222, USA
| | - Yangbin Liu
- Department of Chemistry, University at Albany, State University of New York, 1400 Washington Ave. CH232, Albany, NY, 12222, USA
| | - Zhang Wang
- Department of Chemistry, University at Albany, State University of New York, 1400 Washington Ave. CH232, Albany, NY, 12222, USA
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Affiliation(s)
- Donghui Ma
- Department of Chemistry; University at Albany, State University of New York; 1400 Washington Ave. CH232 Albany NY 12222 USA
| | - Yangbin Liu
- Department of Chemistry; University at Albany, State University of New York; 1400 Washington Ave. CH232 Albany NY 12222 USA
| | - Zhang Wang
- Department of Chemistry; University at Albany, State University of New York; 1400 Washington Ave. CH232 Albany NY 12222 USA
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Ndjakou Lenta B, Chouna JR, Nkeng-Efouet PA, Sewald N. Endiandric Acid Derivatives and Other Constituents of Plants from the Genera Beilschmiedia and Endiandra (Lauraceae). Biomolecules 2015; 5:910-42. [PMID: 26117852 PMCID: PMC4496702 DOI: 10.3390/biom5020910] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Plants of the Lauraceae family are widely used in traditional medicine and are sources of various classes of secondary metabolites. Two genera of this family, Beilschmiedia and Endiandra, have been the subject of numerous investigations over the past decades because of their application in traditional medicine. They are the only source of bioactive endiandric acid derivatives. Noteworthy is that their biosynthesis contains two consecutive non-enzymatic electrocyclic reactions. Several interesting biological activities for this specific class of secondary metabolites and other constituents of the two genera have been reported, including antimicrobial, enzymes inhibitory and cytotoxic properties. This review compiles information on the structures of the compounds described between January 1960 and March 2015, their biological activities and information on endiandric acid biosynthesis, with 104 references being cited.
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Affiliation(s)
- Bruno Ndjakou Lenta
- Department of Chemistry, Higher Teacher Training College, University of Yaoundé 1, P.O. Box 47, Yaoundé, Cameroon
- Organic and Bioorganic Chemistry, Chemistry Department, Bielefeld University, P.O. Box 100131, 33501 Bielefeld, Germany; E-Mail:
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +2376-7509-7561
| | - Jean Rodolphe Chouna
- Department of Chemistry, University of Dschang, P.O. Box 67, Dschang, Cameroon; E-Mails: (J.R.C.); (P.A.N.-E.)
| | - Pepin Alango Nkeng-Efouet
- Department of Chemistry, University of Dschang, P.O. Box 67, Dschang, Cameroon; E-Mails: (J.R.C.); (P.A.N.-E.)
| | - Norbert Sewald
- Organic and Bioorganic Chemistry, Chemistry Department, Bielefeld University, P.O. Box 100131, 33501 Bielefeld, Germany; E-Mail:
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Drew SL, Lawrence AL, Sherburn MS. Unified total synthesis of the natural products endiandric acid A, kingianic acid E, and kingianins A, D, and F. Chem Sci 2015; 6:3886-3890. [PMID: 29218159 PMCID: PMC5707472 DOI: 10.1039/c5sc00794a] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 04/27/2015] [Indexed: 11/21/2022] Open
Abstract
A measure of the strength of a synthetic strategy is its versatility: specifically, whether it allows structurally distinct targets to be prepared. Herein we disclose a unified approach for the total synthesis of natural products of three distinct structural types, all of which occur naturally as racemic mixtures. The point of divergence involves the terminal alkylation of a conjugated tetrayne, and culminates in a significantly shortened synthesis of endiandric acid A (8 steps), the first total synthesis of kingianic acid E (8 steps), and a second-generation synthesis of kingianins A, D, and F (11 steps). Evidence for redox catalysis in the biosynthesis of kingianic acid E is presented.
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Affiliation(s)
- S L Drew
- Research School of Chemistry , Australian National University , Canberra , ACT 2601 , Australia .
| | - A L Lawrence
- Research School of Chemistry , Australian National University , Canberra , ACT 2601 , Australia .
| | - M S Sherburn
- Research School of Chemistry , Australian National University , Canberra , ACT 2601 , Australia .
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Kingianic acids A-G, Endiandric acid analogues from Endiandra kingiana. Molecules 2014; 19:1732-47. [PMID: 24492595 PMCID: PMC6270856 DOI: 10.3390/molecules19021732] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 01/03/2014] [Accepted: 01/23/2014] [Indexed: 11/17/2022] Open
Abstract
A phytochemical investigation of the methanolic extract of the bark of Endiandra kingiana led to the isolation of seven new tetracyclic endiandric acid analogues, kingianic acids A–G (1–7), together with endiandric acid M (8), tsangibeilin B (9) and endiandric acid (10). Their structures were determined by 1D- and 2D-NMR analysis in combination with HRMS experiments. The structure of compounds 9 and 10 were confirmed by single-crystal X-ray diffraction analysis. These compounds were screened for Bcl-xL and Mcl-1 binding affinities and cytotoxic activity on various cancer cell lines. Compound 5 showed moderate cytotoxic activity against human colorectal adeno-carcinoma (HT-29) and lung adenocarcinoma epithelial (A549) cell lines, with IC50 values in the range 15–17 µM, and compounds 3, 6 and 9 exhibited weak binding affinity for the anti-apoptotic protein Mcl-1.
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Drew SL, Lawrence AL, Sherburn MS. Total Synthesis of Kingianins A, D, and F. Angew Chem Int Ed Engl 2013; 52:4221-4. [DOI: 10.1002/anie.201210084] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Indexed: 11/05/2022]
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Williams RB, Martin SM, Hu JF, Norman VL, Goering MG, Loss S, O'Neil-Johnson M, Eldridge GR, Starks CM. Cytotoxic and antibacterial beilschmiedic acids from a Gabonese species of Beilschmiedia. JOURNAL OF NATURAL PRODUCTS 2012; 75:1319-1325. [PMID: 22758788 PMCID: PMC3424616 DOI: 10.1021/np300241d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
High-throughput natural products chemistry methods have facilitated the isolation of eight new (1-8) and two known (9 and 10) beilschmiedic acid derivatives from the leaves of a Gabonese species of Beilschmiedia. Compounds 3-10 were isolated in microgram quantities, and the NMR data for structure elucidation and dereplication were acquired utilizing a Bruker BioSpin TCI 1.7 mm MicroCryoProbe. All of the compounds were screened for cytotoxic and antibacterial activity against NCI-H460 human lung cancer cells and a clinical isolate of methicillin-resistant Staphylococcus aureus, respectively. This is the first report of cytotoxic activity for the endiandric/beilschmiedic acid class of compounds.
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Affiliation(s)
- Russell B Williams
- Lead Discovery and Rapid Structure Elucidation Group, Sequoia Sciences, Inc. , 1912 Innerbelt Business Center Drive, St. Louis, Missouri 63114, USA.
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Huang YT, Chang HS, Wang GJ, Cheng MJ, Chen CH, Yang YJ, Chen IS. Anti-inflammatory endiandric acid analogues from the roots of Beilschmiedia tsangii. JOURNAL OF NATURAL PRODUCTS 2011; 74:1875-1880. [PMID: 21846089 DOI: 10.1021/np200279r] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Bioassay-guided fractionation of roots of Beilschmiedia tsangii led to the isolation of six new endiandric acid analogues: tsangibeilin A (1), tsangibeilin B (2), endiandramide A (3), endiandric acid K (4), endiandric acid L (5), and endiandramide B (6). Also isolated were two new lignans, beilschminol A (7) and tsangin C (8), and six known compounds. The structures of 1-8 were determined by spectroscopic techniques. Compounds 3 and 6 exhibited potent iNOS inhibitory activity, with IC(50) values of 9.59 and 16.40 μM, respectively.
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Affiliation(s)
- Yun-Ting Huang
- Graduate Institute of Natural Products, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan 807, Republic of China
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Leverrier A, Awang K, Guéritte F, Litaudon M. Pentacyclic polyketides from Endiandra kingiana as inhibitors of the Bcl-xL/Bak interaction. PHYTOCHEMISTRY 2011; 72:1443-1452. [PMID: 21550092 DOI: 10.1016/j.phytochem.2011.04.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 04/07/2011] [Accepted: 04/08/2011] [Indexed: 05/30/2023]
Abstract
An in vitro biological screening of Malaysian plants allowed the selection of several species with a significant binding affinity for the antiapoptotic protein Bcl-xL. The chemical investigation of Endiandra kingiana led to the isolation of a series of polyketides named kingianins A-N, having a pentacyclic carbon skeleton described for the first time in nature. Fourteen compounds were isolated as racemic mixtures, and characterized by mass spectrometryand extensive one- and two-dimensional NMR spectroscopy. The (-) and (+) enantiomers of kingianins A and G-L were separated using chiral HPLC, and the absolute configuration of four of them was clearly established by CD analysis. The levorotatory enantiomers showed the more potent binding affinity for Bcl-xL with Ki ranging from 1.0 to 12μM.
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Affiliation(s)
- Aurélie Leverrier
- Centre de Recherche de Gif, Institut de Chimie des Substances Naturelles, CNRS, 1, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France
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Grange R, Gallen M, Schill H, Johns J, Dong L, Parsons P, Reddell P, Gordon V, Bernhardt P, Williams C. [4+2] Cycloaddition Reactions Between 1,8-Disubstituted Cyclooctatetraenes and Diazo Dienophiles: Stereoelectronic Effects, Anticancer Properties and Application to the Synthesis of 7,8-Substituted Bicyclo[4.2.0]octa-2,4-dienes. Chemistry 2010; 16:8894-903. [DOI: 10.1002/chem.200903454] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
The Diels-Alder reaction has both enabled and shaped the art and science of total synthesis over the last few decades to an extent which, arguably, has yet to be eclipsed by any other transformation in the current synthetic repertoire. With myriad applications of this magnificent pericyclic reaction, often as a crucial element in elegant and programmed cascade sequences facilitating complex molecule construction, the Diels-Alder cycloaddition has afforded numerous and unparalleled solutions to a diverse range of synthetic puzzles provided by nature in the form of natural products. In celebration of the 100th anniversary of Alder's birth, selected examples of the awesome power of the reaction he helped to discover are discussed in this review in the context of total synthesis to illustrate its overall versatility and underscore its vast potential which has yet to be fully realized.
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Affiliation(s)
- K C Nicolaou
- Department of Chemistry, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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Yang PS, Cheng MJ, Peng CF, Chen JJ, Chen IS. Endiandric Acid Analogues from the Roots of Beilschmiedia erythrophloia. JOURNAL OF NATURAL PRODUCTS 2009; 72:53-58. [PMID: 19072217 DOI: 10.1021/np800504w] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Investigation of the roots of Beilschmiedia erythrophloia has led to the isolation of seven new endiandric acid analogues, erythrophloins A-F (1-6) and beilcyclone A (7), together with 11 known compounds. The structures of 1-7 were determined using spectroscopic techniques. Two constituents, erythrophloin C (3) and suberosol B (8), exhibited antitubercular activity against Mycobacterium tuberculosis H37Rv, showing MIC values of 50 and 28.9 microg/mL, respectively.
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Affiliation(s)
- Ping-Shin Yang
- Graduate Institute of Natural Products, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan 807, Republic of China
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Abstract
The design and implementation of cascade reactions is a challenging facet of organic chemistry, yet one that can impart striking novelty, elegance, and efficiency to synthetic strategies. The application of cascade reactions to natural products synthesis represents a particularly demanding task, but the results can be both stunning and instructive. This Review highlights selected examples of cascade reactions in total synthesis, with particular emphasis on recent applications therein. The examples discussed herein illustrate the power of these processes in the construction of complex molecules and underscore their future potential in chemical synthesis.
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Affiliation(s)
- K C Nicolaou
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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Oikawa H. Involvement of the Diels–Alderases in the Biosynthesis of Natural Products. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2005. [DOI: 10.1246/bcsj.78.537] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Pericyclic Reactions in Organic Synthesis and Biosynthesis: Synthetic Adventures with Endiandric Acids A–G. ACTA ACUST UNITED AC 1984. [DOI: 10.1016/b978-0-12-450280-2.50010-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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