The Experts below are selected from a list of 1311 Experts worldwide ranked by ideXlab platform
T Tsuchiya - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and antitumor activity of 7-O-[2,6-dideoxy-2-fluoro-5-C-(trifluoromethyl)-alpha-L-talopyranosyl]- daunomycinone and -adriamycinone.
Carbohydrate research, 1999Co-Authors: K Nakai, Y Takagi, T TsuchiyaAbstract:7-O-[2,6-Dideoxy-2-fluoro-5-C-(trifluoromethyl)-alpha-L-talopyranosyl]- daunomycinone and -adriamycinone have been prepared by the coupling of 3,4-di-O-acetyl-2,6-dideoxy-2-fluoro-5-C-(trifluoromethyl)-alpha-L- talopyranosyl iodide with daunomycinone. The key steps in this synthesis are the regioselective fluorination of methyl alpha-D-lyxopyranoside to give the 4-deoxy-4-fluoro-beta-L-ribopyranoside and the C-trifluoromethylation of the aldehydo-L-Ribose Derivative to give the 1,1,1-trifluoro-5-monofluoro-L-altritol Derivative. Antitumor activities of the synthetic products were compared with those for the 2'-deoxy-2'-fluoro and 2',6'-dideoxy-5'-C-trifluoromethyl analogs.
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Synthesis and antitumor activity of 7-O-[2,6-dideoxy-2-fluoro-5-C-(trifluoromethyl)-α-l-talopyranosyl]-daunomycinone and -adriamycinone
Carbohydrate Research, 1999Co-Authors: K Nakai, Y Takagi, T TsuchiyaAbstract:Abstract 7- O -[2,6-Dideoxy-2-fluoro-5- C -(trifluoromethyl)-α- l -talopyranosyl]-daunomycinone and -adriamycinone have been prepared by the coupling of 3,4-di- O -acetyl-2,6-dideoxy-2-fluoro-5- C -(trifluoromethyl)-α- l -talopyranosyl iodide with daunomycinone. The key steps in this synthesis are the regioselective fluorination of methyl α- d -lyxopyranoside to give the 4-deoxy-4-fluoro-β- l -ribopyranoside and the C -trifluoromethylation of the aldehydo - l -Ribose Derivative to give the 1,1,1-trifluoro-5-monofluoro- l -altritol Derivative. Antitumor activities of the synthetic products were compared with those for the 2′-deoxy-2′-fluoro and 2′,6′-dideoxy-5′- C -trifluoromethyl analogs.
Masayuki Inoue - One of the best experts on this subject based on the ideXlab platform.
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Total Synthesis of Resiniferatoxin Enabled by Radical-Mediated Three-Component Coupling and 7-endo Cyclization
Journal of the American Chemical Society, 2017Co-Authors: Satoshi Hashimoto, Shun-ichiro Katoh, Takehiro Kato, Daisuke Urabe, Masayuki InoueAbstract:Resiniferatoxin (1) belongs to a daphnane diterpenoid family and has strong agonistic effects on TRPV1, a transducer of noxious temperature and chemical stimuli. The densely oxygenated trans-fused 5/7/6-tricarbocycle (ABC-ring) of 1 presents a daunting challenge for chemical synthesis. Here we report the development of a novel radical-based strategy for assembling 1 from three components: A-ring 9, allyl stannane 18b, and C-ring 17b. The 6-membered 17b, prepared from d-Ribose Derivative 19, was designed to possess the caged orthoester structure with α-alkoxy selenide as a radical precursor. Upon treatment of 17b with 18b, 9, and V-40, the potently reactive α-alkoxy bridgehead radical was generated from 17b and then sequentially coupled with 9 and 18b to yield 16b. This first radical reaction formed the hindered C9,10-linkage between the A and C-rings and extended the C4-chain on the A-ring in a stereoselective fashion. After derivatization of 16b into 15, the remaining 7-membered B-ring was cyclized in th...
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Total Synthesis of Resiniferatoxin Enabled by Radical-Mediated Three-Component Coupling and 7-endo Cyclization
2017Co-Authors: Satoshi Hashimoto, Shun-ichiro Katoh, Takehiro Kato, Daisuke Urabe, Masayuki InoueAbstract:Resiniferatoxin (1) belongs to a daphnane diterpenoid family and has strong agonistic effects on TRPV1, a transducer of noxious temperature and chemical stimuli. The densely oxygenated trans-fused 5/7/6-tricarbocycle (ABC-ring) of 1 presents a daunting challenge for chemical synthesis. Here we report the development of a novel radical-based strategy for assembling 1 from three components: A-ring 9, allyl stannane 18b, and C-ring 17b. The 6-membered 17b, prepared from d-Ribose Derivative 19, was designed to possess the caged orthoester structure with α-alkoxy selenide as a radical precursor. Upon treatment of 17b with 18b, 9, and V-40, the potently reactive α-alkoxy bridgehead radical was generated from 17b and then sequentially coupled with 9 and 18b to yield 16b. This first radical reaction formed the hindered C9,10-linkage between the A and C-rings and extended the C4-chain on the A-ring in a stereoselective fashion. After derivatization of 16b into 15, the remaining 7-membered B-ring was cyclized in the presence of n-Bu3SnH and V-40 by utilizing the xanthate on the C-ring as the radical precursor and the allylic dithiocarbonate as the terminator. The second radical reaction thus enabled not only the 7-endo cyclization but also construction of the C8-stereocenter and the C6-exo olefin. Tricycle 14 was elaborated into the targeted 1 by a series of highly optimized chemoselective reactions. The present total synthesis of 1 demonstrates the advantages of radical reactions for linking hindered bonds within carbocycles without damaging preexisting functionalities, thereby offering a new strategic design for multistep target-oriented synthesis
Alexandros E. Koumbis - One of the best experts on this subject based on the ideXlab platform.
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A short alternative preparation of the bengazoles polyol side-chain segment.
Carbohydrate research, 2006Co-Authors: John K. Gallos, Christos I. Stathakis, Maria J. Salapassidou, Constantinos E. Grammatoglou, Alexandros E. KoumbisAbstract:Abstract A new short and efficient synthesis of the bengazoles side chain is reported using a sequential Grignard addition–hydroboration approach on a readily available d -Ribose Derivative.
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Synthesis of enantiomerically pure bicyclo[3.1.0]hexanes from D-Ribose by intramolecular cyclopropanation
Journal of the Chemical Society Perkin Transactions 1, 1994Co-Authors: John K. Gallos, Theocharis V. Koftis, Alexandros E. KoumbisAbstract:Highly functionalized optically pure bicyclo[3.1.0]hexan-2-ones 6a and 6b are easily obtained by the Intramolecular cyclopropanation of a D-Ribose Derivative using the iodonium ylide or diazo compound methods, which afford the final products with opposite diastereoselectivities.
K Nakai - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and antitumor activity of 7-O-[2,6-dideoxy-2-fluoro-5-C-(trifluoromethyl)-alpha-L-talopyranosyl]- daunomycinone and -adriamycinone.
Carbohydrate research, 1999Co-Authors: K Nakai, Y Takagi, T TsuchiyaAbstract:7-O-[2,6-Dideoxy-2-fluoro-5-C-(trifluoromethyl)-alpha-L-talopyranosyl]- daunomycinone and -adriamycinone have been prepared by the coupling of 3,4-di-O-acetyl-2,6-dideoxy-2-fluoro-5-C-(trifluoromethyl)-alpha-L- talopyranosyl iodide with daunomycinone. The key steps in this synthesis are the regioselective fluorination of methyl alpha-D-lyxopyranoside to give the 4-deoxy-4-fluoro-beta-L-ribopyranoside and the C-trifluoromethylation of the aldehydo-L-Ribose Derivative to give the 1,1,1-trifluoro-5-monofluoro-L-altritol Derivative. Antitumor activities of the synthetic products were compared with those for the 2'-deoxy-2'-fluoro and 2',6'-dideoxy-5'-C-trifluoromethyl analogs.
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Synthesis and antitumor activity of 7-O-[2,6-dideoxy-2-fluoro-5-C-(trifluoromethyl)-α-l-talopyranosyl]-daunomycinone and -adriamycinone
Carbohydrate Research, 1999Co-Authors: K Nakai, Y Takagi, T TsuchiyaAbstract:Abstract 7- O -[2,6-Dideoxy-2-fluoro-5- C -(trifluoromethyl)-α- l -talopyranosyl]-daunomycinone and -adriamycinone have been prepared by the coupling of 3,4-di- O -acetyl-2,6-dideoxy-2-fluoro-5- C -(trifluoromethyl)-α- l -talopyranosyl iodide with daunomycinone. The key steps in this synthesis are the regioselective fluorination of methyl α- d -lyxopyranoside to give the 4-deoxy-4-fluoro-β- l -ribopyranoside and the C -trifluoromethylation of the aldehydo - l -Ribose Derivative to give the 1,1,1-trifluoro-5-monofluoro- l -altritol Derivative. Antitumor activities of the synthetic products were compared with those for the 2′-deoxy-2′-fluoro and 2′,6′-dideoxy-5′- C -trifluoromethyl analogs.
Satoshi Hashimoto - One of the best experts on this subject based on the ideXlab platform.
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Total Synthesis of Resiniferatoxin Enabled by Radical-Mediated Three-Component Coupling and 7-endo Cyclization
Journal of the American Chemical Society, 2017Co-Authors: Satoshi Hashimoto, Shun-ichiro Katoh, Takehiro Kato, Daisuke Urabe, Masayuki InoueAbstract:Resiniferatoxin (1) belongs to a daphnane diterpenoid family and has strong agonistic effects on TRPV1, a transducer of noxious temperature and chemical stimuli. The densely oxygenated trans-fused 5/7/6-tricarbocycle (ABC-ring) of 1 presents a daunting challenge for chemical synthesis. Here we report the development of a novel radical-based strategy for assembling 1 from three components: A-ring 9, allyl stannane 18b, and C-ring 17b. The 6-membered 17b, prepared from d-Ribose Derivative 19, was designed to possess the caged orthoester structure with α-alkoxy selenide as a radical precursor. Upon treatment of 17b with 18b, 9, and V-40, the potently reactive α-alkoxy bridgehead radical was generated from 17b and then sequentially coupled with 9 and 18b to yield 16b. This first radical reaction formed the hindered C9,10-linkage between the A and C-rings and extended the C4-chain on the A-ring in a stereoselective fashion. After derivatization of 16b into 15, the remaining 7-membered B-ring was cyclized in th...
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Total Synthesis of Resiniferatoxin Enabled by Radical-Mediated Three-Component Coupling and 7-endo Cyclization
2017Co-Authors: Satoshi Hashimoto, Shun-ichiro Katoh, Takehiro Kato, Daisuke Urabe, Masayuki InoueAbstract:Resiniferatoxin (1) belongs to a daphnane diterpenoid family and has strong agonistic effects on TRPV1, a transducer of noxious temperature and chemical stimuli. The densely oxygenated trans-fused 5/7/6-tricarbocycle (ABC-ring) of 1 presents a daunting challenge for chemical synthesis. Here we report the development of a novel radical-based strategy for assembling 1 from three components: A-ring 9, allyl stannane 18b, and C-ring 17b. The 6-membered 17b, prepared from d-Ribose Derivative 19, was designed to possess the caged orthoester structure with α-alkoxy selenide as a radical precursor. Upon treatment of 17b with 18b, 9, and V-40, the potently reactive α-alkoxy bridgehead radical was generated from 17b and then sequentially coupled with 9 and 18b to yield 16b. This first radical reaction formed the hindered C9,10-linkage between the A and C-rings and extended the C4-chain on the A-ring in a stereoselective fashion. After derivatization of 16b into 15, the remaining 7-membered B-ring was cyclized in the presence of n-Bu3SnH and V-40 by utilizing the xanthate on the C-ring as the radical precursor and the allylic dithiocarbonate as the terminator. The second radical reaction thus enabled not only the 7-endo cyclization but also construction of the C8-stereocenter and the C6-exo olefin. Tricycle 14 was elaborated into the targeted 1 by a series of highly optimized chemoselective reactions. The present total synthesis of 1 demonstrates the advantages of radical reactions for linking hindered bonds within carbocycles without damaging preexisting functionalities, thereby offering a new strategic design for multistep target-oriented synthesis
