The Experts below are selected from a list of 1263 Experts worldwide ranked by ideXlab platform
Sangho Koo - One of the best experts on this subject based on the ideXlab platform.
-
The Friedel-Crafts allylation of a Prenyl Group stabilized by a sulfone moiety: expeditious syntheses of ubiquinones and menaquinones.
The Journal of organic chemistry, 2003Co-Authors: Jae-hong Min, Jun-sup Lee, Jae-deuk Yang, Sangho KooAbstract:An efficient synthetic method for the protected p-hydroquinone compounds 4 containing the C5 trans allylic sulfone moiety has been developed by the direct Friedel−Crafts allylation of the protected dihydroquinone 2 with 4-chloro-2-methyl-1-phenylsulfonyl-2-butene (7a) or 4-hydroxy-2-methyl-1-phenylsulfonyl-2-butene (7b). Expeditious total syntheses of coenzyme Q-10 and vitamin K2(20) have been demonstrated from these valuable key compounds 4a and 4b.
-
the friedel crafts allylation of a Prenyl Group stabilized by a sulfone moiety expeditious syntheses of ubiquinones and menaquinones
Journal of Organic Chemistry, 2003Co-Authors: Jae-hong Min, Jun-sup Lee, Jae-deuk Yang, Sangho KooAbstract:An efficient synthetic method for the protected p-hydroquinone compounds 4 containing the C5 trans allylic sulfone moiety has been developed by the direct Friedel−Crafts allylation of the protected...
Yumiko Suzuki - One of the best experts on this subject based on the ideXlab platform.
-
Total Synthesis of Termicalcicolanone A via Organocatalysis and Regioselective Claisen Rearrangement
Organic letters, 2019Co-Authors: Saki Ito, Taiki Kitamura, Sundaram Arulmozhiraja, Kei Manabe, Hiroaki Tokiwa, Yumiko SuzukiAbstract:A total synthesis of an anticancer xanthone natural product termicalcicolanone A utilizing multiple nucleophilic aromatic substitutions and pericyclic reactions has been developed. The pyrano[3,2-b]xanthen-6-one scaffold was constructed via NHC-catalyzed aroylation to produce the benzophenone intermediate, Claisen cyclization to form the pyran ring, and intramolecular 1,4-addition to construct the xanthone framework. The Prenyl Group was introduced in the final stages of the synthesis through regioselective Claisen rearrangement. The synthesis has been achieved in 19 steps.
-
Total Synthesis of Termicalcicolanone A via Organocatalysis and Regioselective Claisen Rearrangement
2019Co-Authors: Saki Ito, Taiki Kitamura, Sundaram Arulmozhiraja, Kei Manabe, Hiroaki Tokiwa, Yumiko SuzukiAbstract:A total synthesis of an anticancer xanthone natural product termicalcicolanone A utilizing multiple nucleophilic aromatic substitutions and pericyclic reactions has been developed. The pyrano[3,2-b]xanthen-6-one scaffold was constructed via NHC-catalyzed aroylation to produce the benzophenone intermediate, Claisen cyclization to form the pyran ring, and intramolecular 1,4-addition to construct the xanthone framework. The Prenyl Group was introduced in the final stages of the synthesis through regioselective Claisen rearrangement. The synthesis has been achieved in 19 steps
Paulo A. Melo - One of the best experts on this subject based on the ideXlab platform.
-
Synthesis and pharmacological evaluation of Prenylated and benzylated pterocarpans against snake venom
Bioorganic & Medicinal Chemistry Letters, 2004Co-Authors: Alcides J. M. Da Silva, Antonio L. Coelho, Raphael A. M. Moraes, Diogo Pinheiro, Emerson Z. Arruda, Fabrício F.a. Fernandes, Alessandro B. C. Simas, Paulo R R Costa, Paulo A. MeloAbstract:Edunol (3), a pterocarpan isolated from Harpalyce brasiliana, a plant used in the northeast of Brazil against snakebites, was obtained by synthesis and showed antimyotoxic, antiproteolytic and PLA2 inhibitor properties. These proprieties could be improved through the synthesis of a bioisoster (5), where the Prenyl Group was replaced by the benzyl Group.
-
Synthesis and pharmacological evaluation of Prenylated and benzylated pterocarpans against snake venom
Bioorganic & Medicinal Chemistry Letters, 2004Co-Authors: Alcides J. M. Da Silva, Antonio L. Coelho, Raphael A. M. Moraes, Diogo Pinheiro, Emerson Z. Arruda, Fabrício F.a. Fernandes, Alessandro B. C. Simas, Paulo R R Costa, Paulo A. MeloAbstract:Edunol (3), a pterocarpan isolated from Harpalyce brasiliana, a plant used in the northeast of Brazil against snakebites, was obtained by synthesis and showed antimyotoxic, antiproteolytic and PLA2 inhibitor properties. These proprieties could be improved through the synthesis of a bioisoster (5), where the Prenyl Group was replaced by the benzyl Group.
Thomas Lindel - One of the best experts on this subject based on the ideXlab platform.
-
Doubly Prenylated tryptamines: cytotoxicity, antimicrobial activity and cyclisation to the marine natural product flustramine A
Organic & biomolecular chemistry, 2013Co-Authors: Santosh Kumar Adla, Florenz Sasse, Gerhard Kelter, Heinz-herbert Fiebig, Thomas LindelAbstract:The marine natural product flustramine A was synthesised via oxidative cyclisation of Nb-methylated 1-Prenyl-2-tert-Prenyl-6-bromotryptamine and subsequent reduction of the resulting amidinium salt. Only the tert-Prenyl Group migrated, whereas the 1-Prenyl Group remained in place. Interestingly, the 2-tert-Prenylated precursor revealed to be the biologically most active of our entire series of 21 compounds. Required for cytotoxicity and antimicrobial activity was the presence of a non-cyclised tryptamine side chain carrying a free secondary amine, whereas the presence of a 6-bromo substituent did not enhance cytotoxicity. In a panel of 42 human tumor cell lines, most sensitive were the lung and mammary cancer cell lines LXFA629L (IC50 1.9 μM) and MAXF401NL (IC50 2.4 μM), respectively. In a serial dilution assay, satisfying IC50 values of 5.9 μM against Micrococcus luteus and 7.7 μM each against Mycobacterium phlei were determined for Nb-methyl-1-Prenyl-2-tert-Prenyl-6-bromotryptamine.
-
Study on the NBS-Induced Rearrangement of 2-tert-Prenyltryptamines
Synthesis, 2010Co-Authors: Santosh Kumar Adla, Gregor Golz, Peter G. Jones, Thomas LindelAbstract:Treatment of 2-tert-Prenyltryptamines with N-bromo-succinimide gives clean access to the marine natural product flustramine C and analogues with the tert-Prenyl Group shifted to the 3a-position of the resulting pyrrolo[2,3-b]indole (70-80%). Dihydroflustramine C was obtained by DIBAL-H reduction of flustramine C. Bromination or N-methylation of the indole moiety does not influence the course of the rearrangement.
-
Total synthesis of flustramine C via dimethylallyl rearrangement.
Organic letters, 2007Co-Authors: Thomas Lindel, Gregor Golz, Laura Bräuchle, Petra BöhrerAbstract:The marine natural product flustramine C from the bryozoan Flustra foliacea was synthesized in five steps and 38% yield starting from Nb-methyltryptamine. The key step is the biomimetic oxidation of the natural product deformylflustrabromine causing selective 1,2-rearrangement of the inverse Prenyl Group. By 1H,15N HMBC experiments, it is unambiguously shown that the reaction with t-BuOCl commences with chlorination of the side chain nitrogen. Deformylflustrabromine itself was synthesized via Danishefsky inverse Prenylation. [reaction: see text].
Yi Tang - One of the best experts on this subject based on the ideXlab platform.
-
Enzyme-Catalyzed Intramolecular Enantioselective Hydroalkoxylation
2017Co-Authors: Shu-shan Gao, Marc Garcia-borràs, Joyann S. Barber, Yang Hai, Abing Duan, Neil K. Garg, K. N. Houk, Yi TangAbstract:Hydroalkoxylation is a powerful and efficient method of forming C–O bonds and cyclic ethers in synthetic chemistry. In studying the biosynthesis of the fungal natural product herqueinone, we identified an enzyme that can perform an intramolecular enantioselective hydroalkoxylation reaction. PhnH catalyzes the addition of a phenol to the terminal olefin of a reverse Prenyl Group to give a dihydrobenzofuran product. The enzyme accelerates the reaction by 3 × 105-fold compared to the uncatalyzed reaction. PhnH belongs to a superfamily of proteins with a domain of unknown function (DUF3237), of which no member has a previously verified function. The discovery of PhnH demonstrates that enzymes can be used to promote the enantioselective hydroalkoxylation reaction and form cyclic ethers
-
tandem Prenyltransferases catalyze isoprenoid elongation and complexity generation in biosynthesis of quinolone alkaloids
Journal of the American Chemical Society, 2015Co-Authors: Zhajun Zhan, Dehai Li, Mancheng Tang, Ralph A Cacho, Kenji Watanabe, Yi TangAbstract:Modification of natural products with Prenyl Groups and the ensuing oxidative transformations are important for introducing structural complexity and biological activities. Penigequinolones (1) are potent insecticidal alkaloids that contain a highly modified 10-carbon Prenyl Group. Here we reveal an iterative Prenylation mechanism for installing the 10-carbon unit using two aromatic Prenyltransferases (PenI and PenG) present in the gene cluster of 1 from Penicillium thymicola. The initial Friedel–Crafts alkylation is catalyzed by PenI to yield dimethylallyl quinolone 6. The five-carbon side chain is then dehydrogenated by a flavin-dependent monooxygenase to give aryl diene 9, which serves as the electron-rich substrate for a second alkylation with dimethylallyl diphosphate to yield stryrenyl product 10. The completed, oxidized 10-carbon Prenyl Group then undergoes further structural morphing to yield yaequinolone C (12), the immediate precursor of 1. Our studies have therefore uncovered an unprecedented p...
-
tandem Prenyltransferases catalyze isoprenoid elongation and complexity generation in biosynthesis of quinolone alkaloids
Journal of the American Chemical Society, 2015Co-Authors: Yi Zou, Zhajun Zhan, Mancheng Tang, Ralph A Cacho, Kenji Watanabe, Yi TangAbstract:Modification of natural products with Prenyl Groups and the ensuing oxidative transformations are important for introducing structural complexity and biological activities. Penigequinolones (1) are potent insecticidal alkaloids that contain a highly modified 10-carbon Prenyl Group. Here we reveal an iterative Prenylation mechanism for installing the 10-carbon unit using two aromatic Prenyltransferases (PenI and PenG) present in the gene cluster of 1 from Penicillium thymicola. The initial Friedel-Crafts alkylation is catalyzed by PenI to yield dimethylallyl quinolone 6. The five-carbon side chain is then dehydrogenated by a flavin-dependent monooxygenase to give aryl diene 9, which serves as the electron-rich substrate for a second alkylation with dimethylallyl diphosphate to yield stryrenyl product 10. The completed, oxidized 10-carbon Prenyl Group then undergoes further structural morphing to yield yaequinolone C (12), the immediate precursor of 1. Our studies have therefore uncovered an unprecedented Prenyl chain extension mechanism in natural product biosynthesis.
-
Tandem Prenyltransferases Catalyze Isoprenoid Elongation and Complexity Generation in Biosynthesis of Quinolone Alkaloids
2015Co-Authors: Yi Zou, Zhajun Zhan, Mancheng Tang, Kenji Watanabe, Ralph A. Cacho, Yi TangAbstract:Modification of natural products with Prenyl Groups and the ensuing oxidative transformations are important for introducing structural complexity and biological activities. Penigequinolones (1) are potent insecticidal alkaloids that contain a highly modified 10-carbon Prenyl Group. Here we reveal an iterative Prenylation mechanism for installing the 10-carbon unit using two aromatic Prenyltransferases (PenI and PenG) present in the gene cluster of 1 from Penicillium thymicola. The initial Friedel–Crafts alkylation is catalyzed by PenI to yield dimethylallyl quinolone 6. The five-carbon side chain is then dehydrogenated by a flavin-dependent monooxygenase to give aryl diene 9, which serves as the electron-rich substrate for a second alkylation with dimethylallyl diphosphate to yield stryrenyl product 10. The completed, oxidized 10-carbon Prenyl Group then undergoes further structural morphing to yield yaequinolone C (12), the immediate precursor of 1. Our studies have therefore uncovered an unprecedented Prenyl chain extension mechanism in natural product biosynthesis
