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Nallappan S, Lapinskaite R, Hájíček J, Kunák D, Čambal P, Nečas D, Císařová I, Atalay HN, Tumer TB, Tarábek J, Schwarzová-Pecková K, Rycek L. The Biomimetic Synthesis of Polyarylated Fluorenes, Relevant to Selaginellaceae Polyphenols, Leading to the Spontaneous Formation of Stable Radicals. Chempluschem 2024; 89:e202300410. [PMID: 37943550 DOI: 10.1002/cplu.202300410] [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] [Received: 07/31/2023] [Revised: 10/31/2023] [Accepted: 11/08/2023] [Indexed: 11/10/2023]
Abstract
This work reports a biomimetic synthesis of polyarylated fluorene derivatives. The molecules are formed via intramolecular electrophilic aromatic substitution, resembling a cyclization leading towards the natural selaginpulvilins from selaginellins. The scope of the reaction was investigated, and the products were obtained in 60-95 % yields. Some of the compounds decompose to a stable radical. We investigated the nature and the origin of the radical using experimental methods, including EPR or electrochemical measurements, as well as theoretical methods, such as DFT calculations. Based on our observations, we hypothesize, that phenoxy radicals are formed in the first instance, which however undergo internal rearrangement to thermodynamically more stable carbon-centered radicals. The preliminary data also show the cytotoxic properties of some of the molecules.
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Affiliation(s)
- Sundaravelu Nallappan
- Department of Organic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 00, Prague, Czech Republic
| | - Ringaile Lapinskaite
- Department of Organic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 00, Prague, Czech Republic
- Department of Organic Chemistry, Center for Physical Sciences and Technology, Akademijos g. 7, Vilnius, 08412, Lithuania
| | - Josef Hájíček
- Department of Organic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 00, Prague, Czech Republic
| | - Dominik Kunák
- Department of Organic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 00, Prague, Czech Republic
| | - Peter Čambal
- Department of Analytical Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 00, Prague, Czech Republic
| | - David Nečas
- Department of Organic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 00, Prague, Czech Republic
| | - Ivana Císařová
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 00, Prague, Czech Republic
| | - Hazal Nazlıcan Atalay
- Department of Molecular Biology and Genetics, Faculty of Arts and Science, Canakkale Onsekiz Mart University, Canakkale, 17020, Turkey
| | - Tugba B Tumer
- Department of Molecular Biology and Genetics, Faculty of Arts and Science, Canakkale Onsekiz Mart University, Canakkale, 17020, Turkey
| | - Ján Tarábek
- Institute of Organic Chemistry and Biochemistry, Academy of Science of the Czech Republic, Flemingovo nám. 2, 166 10, Prague, Czech Republic
| | - Karolina Schwarzová-Pecková
- Department of Analytical Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 00, Prague, Czech Republic
| | - Lukas Rycek
- Department of Organic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 00, Prague, Czech Republic
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2
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Jiang S, Du S, Bai J, Chen X, Liang M, Lin S, Luo MJ, Song XR, Xiao Q. Cascade Cyclization of 1,5-Diynols and (RO) 2P(O)SH to Construct Benzo[ b]fluorenyl S-Alkyl Phosphorothioates under Catalyst-Free Conditions. J Org Chem 2023; 88:14571-14586. [PMID: 37789588 DOI: 10.1021/acs.joc.3c01596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
An efficient and practical cascade cyclization of 1,5-diynols with (RO)2P(O)SH as the acid promoter and nucleophile under mild conditions was developed. A variety of highly substituted benzo[b]fluorenyl-containing S-alkyl phosphorothioates were successfully constructed in moderate to excellent yields. Furthermore, this protocol exhibited good functional group tolerance, a broad substrate scope, and potential practical applications, with water as the only byproduct. The reaction proceeded with allenyl thiophosphate as a key intermediate, followed by a Schmittel-type cyclization process to produce the target product.
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Affiliation(s)
- Shimin Jiang
- Institute of Organic Chemistry, Jiangxi Science &Technology Normal University, Key Laboratory of Organic Chemistry, Jiangxi Province, Nanchang 330013, China
| | - Sha Du
- Institute of Organic Chemistry, Jiangxi Science &Technology Normal University, Key Laboratory of Organic Chemistry, Jiangxi Province, Nanchang 330013, China
| | - Jiang Bai
- Institute of Organic Chemistry, Jiangxi Science &Technology Normal University, Key Laboratory of Organic Chemistry, Jiangxi Province, Nanchang 330013, China
| | - Xi Chen
- Institute of Organic Chemistry, Jiangxi Science &Technology Normal University, Key Laboratory of Organic Chemistry, Jiangxi Province, Nanchang 330013, China
| | - Meng Liang
- Institute of Organic Chemistry, Jiangxi Science &Technology Normal University, Key Laboratory of Organic Chemistry, Jiangxi Province, Nanchang 330013, China
| | - Shihong Lin
- Institute of Organic Chemistry, Jiangxi Science &Technology Normal University, Key Laboratory of Organic Chemistry, Jiangxi Province, Nanchang 330013, China
| | - Mu-Jia Luo
- Institute of Organic Chemistry, Jiangxi Science &Technology Normal University, Key Laboratory of Organic Chemistry, Jiangxi Province, Nanchang 330013, China
| | - Xian-Rong Song
- Institute of Organic Chemistry, Jiangxi Science &Technology Normal University, Key Laboratory of Organic Chemistry, Jiangxi Province, Nanchang 330013, China
| | - Qiang Xiao
- Institute of Organic Chemistry, Jiangxi Science &Technology Normal University, Key Laboratory of Organic Chemistry, Jiangxi Province, Nanchang 330013, China
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Du S, Jiang S, Yang R, Jin F, Huang H, Tian WF, Zhou ZZ, Song XR, Xiao Q. Direct Synthesis of Benzo[ b]fluorenyl Thiophosphates via Tandem Cyclization of Diynols with (RO) 2P(O)SH. Org Lett 2023. [PMID: 36795512 DOI: 10.1021/acs.orglett.3c00009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
A general and metal-free protocol for the construction of benzo[b]fluorenyl thiophosphates was developed through the cascade cyclization of easily prepared diynols and (RO)2P(O)SH, with water as the only byproduct. The novel transformation involved the allenyl thiophosphate as the key intermediate, followed by Schmittel-type cyclization to achieve the desired products. Notably, (RO)2P(O)SH acted not only as a nucleophile but also as an acid-promoter to initiate the reaction.
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Affiliation(s)
- Sha Du
- Institute of Organic Chemistry, Jiangxi Science & Technology Normal University, Key Laboratory of Organic Chemistry, Nanchang 330013, Jiangxi Province, P.R. China
| | - Shimin Jiang
- Institute of Organic Chemistry, Jiangxi Science & Technology Normal University, Key Laboratory of Organic Chemistry, Nanchang 330013, Jiangxi Province, P.R. China
| | - Ruchun Yang
- Institute of Organic Chemistry, Jiangxi Science & Technology Normal University, Key Laboratory of Organic Chemistry, Nanchang 330013, Jiangxi Province, P.R. China
| | - Fengyan Jin
- Institute of Organic Chemistry, Jiangxi Science & Technology Normal University, Key Laboratory of Organic Chemistry, Nanchang 330013, Jiangxi Province, P.R. China
| | - Haiyang Huang
- Institute of Organic Chemistry, Jiangxi Science & Technology Normal University, Key Laboratory of Organic Chemistry, Nanchang 330013, Jiangxi Province, P.R. China
| | - Wan-Fa Tian
- Institute of Organic Chemistry, Jiangxi Science & Technology Normal University, Key Laboratory of Organic Chemistry, Nanchang 330013, Jiangxi Province, P.R. China
| | - Zhao-Zhao Zhou
- College of Chemistry and Food Science, Nanchang Normal University, Nanchang, 330000, P.R. China
| | - Xian-Rong Song
- Institute of Organic Chemistry, Jiangxi Science & Technology Normal University, Key Laboratory of Organic Chemistry, Nanchang 330013, Jiangxi Province, P.R. China
| | - Qiang Xiao
- Institute of Organic Chemistry, Jiangxi Science & Technology Normal University, Key Laboratory of Organic Chemistry, Nanchang 330013, Jiangxi Province, P.R. China
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Lapinskaite R, Atalay HN, Malatinec Š, Donmez S, Cinar ZO, Schwarz PF, Perhal AF, Císařová I, Labanauskas L, Karpiński TM, Dirsch VM, Tumer TB, Rycek L. Synthesis of Selagibenzophenone A and Its Derivatives for Evaluation of Their Antiproliferative, RORγ Inverse Agonistic, and Antimicrobial Effect**. ChemistrySelect 2023. [DOI: 10.1002/slct.202204816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Affiliation(s)
- Ringaile Lapinskaite
- Department of Organic Chemistry Faculty of Science Charles University Hlavova 8 128 00 Praha 2 Czech Republic
- Department of Organic Chemistry Center for Physical Sciences and Technology Akademijos g. 7 Vilnius 08412 Lithuania
| | - Hazal Nazlıcan Atalay
- Graduate Program of Molecular Biology and Genetics School of Graduate Studies Canakkale Onsekiz Mart University Canakkale 17020 Turkey
| | - Štefan Malatinec
- Department of Organic Chemistry Faculty of Science Charles University Hlavova 8 128 00 Praha 2 Czech Republic
| | - Serhat Donmez
- Graduate Program of Molecular Biology and Genetics School of Graduate Studies Canakkale Onsekiz Mart University Canakkale 17020 Turkey
| | - Zeynep Ozlem Cinar
- Graduate Program of Molecular Biology and Genetics School of Graduate Studies Canakkale Onsekiz Mart University Canakkale 17020 Turkey
| | - Patrik F. Schwarz
- Department of Pharmaceutical Sciences University of Vienna Josef-Holaubek-Platz 2 1090 Vienna Austria
| | - Alexander F. Perhal
- Department of Pharmaceutical Sciences University of Vienna Josef-Holaubek-Platz 2 1090 Vienna Austria
| | - Ivana Císařová
- Department of Inorganic Chemistry Faculty of Science Charles University Hlavova 8 128 00 Praha 2 Czech Republic
| | - Linas Labanauskas
- Department of Organic Chemistry Center for Physical Sciences and Technology Akademijos g. 7 Vilnius 08412 Lithuania
| | - Tomasz M. Karpiński
- Chair and Department of Medical Microbiology Poznań University of Medical Sciences Wieniawskiego 3 61-712 Poznań Poland
| | - Verena M. Dirsch
- Department of Pharmaceutical Sciences University of Vienna Josef-Holaubek-Platz 2 1090 Vienna Austria
| | - Tugba Boyunegmez Tumer
- Department of Molecular Biology and Genetics Faculty of Arts and Science Canakkale Onsekiz Mart University Canakkale 17020 Turkey
| | - Lukas Rycek
- Department of Organic Chemistry Faculty of Science Charles University Hlavova 8 128 00 Praha 2 Czech Republic
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Le A, Gupta S, Xu M, Xia Y, Lee D. Development of an Allenyne-Alkyne [4+2] Cycloaddition and its Application to Total Synthesis of Selaginpulvilin A. Chemistry 2022; 28:e202202015. [PMID: 35771213 PMCID: PMC9805236 DOI: 10.1002/chem.202202015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Indexed: 01/09/2023]
Abstract
A new [4+2] cycloaddition of allenyne-alkyne is developed. The reaction is believed to proceed with forming an α,3-dehydrotoluene intermediate. This species behaves as a σπ-diradical to react with a hydrogen atom donor, whereas it displays a zwitterionic reactivity toward weak nucleophiles. The efficiency of trapping α,3-dehydrotoluene depends not only on its substituents but also the trapping agents. Notable features of the reaction are the activating role of the extra alkyne of the 1,3-diyne that reacts with the allenyne moiety and the opposite mode of trapping with oxygen and nitrogen nucleophiles. Oxygen nucleophiles result in the oxygen-end incorporation at the benzylic position of the α,3-dehydrotoluene, whereas with amine nucleophiles the nitrogen-end is incorporated into the aromatic core. Relying on the allenyne-alkyne cycloaddition as an enabling strategy, a concise total synthesis of phosphodiesterase-4 inhibitory selaginpulvilin A is realized.
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Affiliation(s)
- Anh Le
- Department of ChemistryUniversity of Illinois Chicago845 West Taylor Street60607ChicagoIllinoisUSA
| | - Saswata Gupta
- Department of ChemistryUniversity of Illinois Chicago845 West Taylor Street60607ChicagoIllinoisUSA
| | - Man Xu
- College of Chemistry and Materials EngineeringWenzhou University325035WenzhouZhejiang ProvinceP. R. China
| | - Yuanzhi Xia
- College of Chemistry and Materials EngineeringWenzhou University325035WenzhouZhejiang ProvinceP. R. China
| | - Daesung Lee
- Department of ChemistryUniversity of Illinois Chicago845 West Taylor Street60607ChicagoIllinoisUSA
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Mei H, Wang N, Li Z, Han J. Intramolecular Appel Reaction of Trifluoromethylated β-Keto Diazos Enabling Assembly of Trifluoromethylpyrazoles. Org Lett 2022; 24:2258-2263. [PMID: 35297254 DOI: 10.1021/acs.orglett.2c00738] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A method for the generation of trifluoromethylated β-keto diazos and their applications in intramolecular Appel type reactions are reported. The key success of this reaction is a diazo species as an N-nucleophile in Appel reactions. This reaction is conducted under mild conditions and has a broad substrate scope, affording trifluoromethylpyrazoles in ≤94% yields. This protocol represents a new type of Appel reaction and also a new reaction mode of fluoro diazoalkanes.
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Affiliation(s)
- Haibo Mei
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, China
| | - Nana Wang
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, China
| | - Ziyi Li
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, China
| | - Jianlin Han
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, China
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7
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Kunák D, Mateus M, Rycek L. Synthesis and Structure Confirmation of Selagibenzophenone C. European J Org Chem 2022. [DOI: 10.1002/ejoc.202200014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Dominik Kunák
- Charles University Faculty of Science: Univerzita Karlova Prirodovedecka fakulta Department of Organic Chemistry CZECH REPUBLIC
| | - Miguel Mateus
- Charles University Faculty of Science: Univerzita Karlova Prirodovedecka fakulta Department of Organic Chemistry CZECH REPUBLIC
| | - Lukas Rycek
- Charles University Faculty of Science: Univerzita Karlova Prirodovedecka fakulta Departmet of Organic Chemistry Hlavova 8 128 40 Prague CZECH REPUBLIC
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Pankhade YA, Pandey R, Fatma S, Ahmad F, Anand RV. TfOH-Catalyzed Intramolecular Annulation of 2-(Aryl)-Phenyl-Substituted p-Quinone Methides under Continuous Flow: Total Syntheses of Selaginpulvilin I and Isoselagintamarlin A. J Org Chem 2022; 87:3363-3377. [PMID: 35107013 DOI: 10.1021/acs.joc.1c02980] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
In this article, we describe a convenient method to access 9-aryl fluorene derivatives through a TfOH-catalyzed intramolecular 1,6-conjugate arylation of 2-(aryl)-phenyl-substituted p-quinone methides (QMs) under continuous flow using the microreaction technique. This method was found to be very effective for most of the p-QMs, and the corresponding 9-aryl fluorene derivatives were obtained in moderate to excellent yields. Moreover, this protocol was further elaborated to the first total syntheses of selaginpulvilin I and isoselagintamarlin A.
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Affiliation(s)
- Yogesh A Pankhade
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Knowledge City, S. A. S. Nagar, Manauli, Punjab 140306, India
| | - Rajat Pandey
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Knowledge City, S. A. S. Nagar, Manauli, Punjab 140306, India
| | - Shaheen Fatma
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Knowledge City, S. A. S. Nagar, Manauli, Punjab 140306, India
| | - Feroz Ahmad
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Knowledge City, S. A. S. Nagar, Manauli, Punjab 140306, India
| | - Ramasamy Vijaya Anand
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Knowledge City, S. A. S. Nagar, Manauli, Punjab 140306, India
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Jiang S, Ma H, Yang R, Song XR, Xiao Q. Recent advances in the cascade reactions of enynols/diynols for the synthesis of carbo- and heterocycles. Org Chem Front 2022. [DOI: 10.1039/d2qo01154a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This review summaries a view of the advances in the cascade reactions of enynols/diynols for the construction of carbo- and heterocycles.
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Affiliation(s)
- Shimin Jiang
- Institute of Organic Chemistry, Jiangxi Science & Technology Normal University, Key Laboratory of Organic Chemistry, Jiangxi Province, Nanchang 330013, China
| | - Haojie Ma
- Key Laboratory of New Energy & New Functional Materials, College of Chemistry and Chemical Engineering, Yan'an University, Yan'an, Shaanxi, 716000, P. R. China
| | - Ruchun Yang
- Institute of Organic Chemistry, Jiangxi Science & Technology Normal University, Key Laboratory of Organic Chemistry, Jiangxi Province, Nanchang 330013, China
| | - Xian-Rong Song
- Institute of Organic Chemistry, Jiangxi Science & Technology Normal University, Key Laboratory of Organic Chemistry, Jiangxi Province, Nanchang 330013, China
| | - Qiang Xiao
- Institute of Organic Chemistry, Jiangxi Science & Technology Normal University, Key Laboratory of Organic Chemistry, Jiangxi Province, Nanchang 330013, China
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Ratovelomanana-Vidal V, Matton P, Huvelle S, Haddad M, Phansavath P. Recent Progress in Metal-Catalyzed [2+2+2] Cycloaddition Reactions. SYNTHESIS-STUTTGART 2021. [DOI: 10.1055/s-0040-1719831] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
AbstractMetal-catalyzed [2+2+2] cycloaddition is a powerful tool that allows rapid construction of functionalized 6-membered carbo- and heterocycles in a single step through an atom-economical process with high functional group tolerance. The reaction is usually regio- and chemoselective although selectivity issues can still be challenging for intermolecular reactions involving the cross-[2+2+2] cycloaddition of two or three different alkynes and various strategies have been developed to attain high selectivities. Furthermore, enantioselective [2+2+2] cycloaddition is an efficient means to create central, axial, and planar chirality and a variety of chiral organometallic complexes can be used for asymmetric transition-metal-catalyzed inter- and intramolecular reactions. This review summarizes the recent advances in the field of [2+2+2] cycloaddition.1 Introduction2 Formation of Carbocycles2.1 Intermolecular Reactions2.1.1 Cyclotrimerization of Alkynes2.1.2 [2+2+2] Cycloaddition of Two Different Alkynes2.1.3 [2+2+2] Cycloaddition of Alkynes/Alkenes with Alkenes/Enamides2.2 Partially Intramolecular [2+2+2] Cycloaddition Reactions2.2.1 Rhodium-Catalyzed [2+2+2] Cycloaddition2.2.2 Molybdenum-Catalyzed [2+2+2] Cycloaddition2.2.3 Cobalt-Catalyzed [2+2+2] Cycloaddition2.2.4 Ruthenium-Catalyzed [2+2+2] Cycloaddition2.2.5 Other Metal-Catalyzed [2+2+2] Cycloaddition2.3 Totally Intramolecular [2+2+2] Cycloaddition Reactions3 Formation of Heterocycles3.1 Cycloaddition of Alkynes with Nitriles3.2 Cycloaddition of 1,6-Diynes with Cyanamides3.3 Cycloaddition of 1,6-Diynes with Selenocyanates3.4 Cycloaddition of Imines with Allenes or Alkenes3.5 Cycloaddition of (Thio)Cyanates and Isocyanates3.6 Cycloaddition of 1,3,5-Triazines with Allenes3.7 Cycloaddition of Aldehydes with Enynes or Allenes/Alkenes3.8 Totally Intramolecular [2+2+2] Cycloaddition Reactions4 Conclusion
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Cross-Coupling as a Key Step in the Synthesis and Structure Revision of the Natural Products Selagibenzophenones A and B. Catalysts 2021. [DOI: 10.3390/catal11060708] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Selagibenzophenone A (1) and its isomer selagibenzophenone B (2) were recently described as natural products from Selaginella genus plants with PDE4 inhibitory activity. Herein, we report the first total syntheses of both compounds. By comparing spectroscopic data of the synthetic compounds with reported data for the isolated material, we demonstrate that the structure of one of the two natural products was incorrectly assigned, and that in fact isolated selagibenzophenone A and selagibenzophenone B are identical compounds. The synthetic strategy for both 1 and 2 is based on a cross-coupling reaction and on the addition of organometallic species to assemble the framework of the molecules. Identifying a suitable starting material with the correct substitution pattern is crucial because its pattern is reflected in that of the targeted compounds. These syntheses are finalized via global deprotection. Protecting the phenols as methoxy groups provides the possibility for partial control over the selectivity in the demethylation thanks to differences in the reactivity of the various methoxy groups. Our findings may help in future syntheses of derivatives of the biologically active natural product and in understanding the structure–activity relationship.
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