- Late-stage C-H amination of abietane diterpenoids
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This study aims at highlighting the synthetic versatility of the rhodium-catalyzed C-H amination reactions using iodine(iii) oxidants for the late-stage functionalization of natural products. Inter-and intramolecular nitrene insertions have been performed from various abietane diterpenoids, leading to the amination of the C-3, C-6, C-7, C-11 and C-15 positions. Ca. 20 aminated compounds have been isolated with yields of up to 86% and high levels of regio-, chemo-and stereoselectivities.
- Lapuh, María Ivana,Dana, Alejandro,Di Chenna, Pablo H.,Darses, Benjamin,Durán, Fernando J.,Dauban, Philippe
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supporting information
p. 4736 - 4746
(2019/05/24)
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- Concise total syntheses of palominol, dolabellatrienone, β-araneosene, and isoedunol via an enantioselective Diels-Alder macrobicyclization
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Concise total syntheses of four members of the dolabellane family of diterpenoid natural products are reported. Key features of the developed route include the first demonstration of an enantioselective, intramolecular Type I Diels-Alder macrobicyclization, the first example of a stereoselective π-allyl Stille coupling reaction involving a farnesyl-derived intermediate, a powerful new reagent for the formation of dithianes with acid-sensitive molecules, and a unique and highly efficient ring-contraction sequence based on a modified Wolff photochemical rearrangement. Copyright
- Snyder, Scott A.,Corey
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p. 740 - 742
(2007/10/03)
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- Synthesis of trinorditerpenoid derivatives and evaluation of antimicrobial and cytotoxic activity
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The synthesis of optically active trinorditerpenes was carried out, and their antimicrobial and antitumor activity was tested. The synthetic derivative 12-hydroxypodocarpa-8,11,13-triene (7) showed GI50 at 6.6 μM against breast cancer MDA-MB-43
- Alonso,Gomis,Taddei,Sajo
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p. 315 - 321
(2008/02/01)
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- A general asymmetric access to the podocarpane diterpenoids
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An efficient and enantiocontrolled total synthesis of (+)-O-methylpodocarpic acid 2 has been accomplished by employing a combined strategy of the lipase-mediated kinetic resolution of the tricyclic allyl alcohol (±)-7 and a highly diastereoselective silylmethyl radical cyclization of 5 leading to the tetracyclic silyl ether 4.
- Fujiwara, Yoko,Yamato, Toshihiro,Bando, Toshikazu,Shishido, Kozo
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p. 2793 - 2799
(2007/10/03)
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- Asymmetric Induction in Mn(III)-Based Oxidative Free-Radical Cyclizations of Phenylmenthyl Acetoacetates and 2,5-Dimethylpyrrolidine Acetoacetamides
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Mn(III)-based oxidative free-radical cyclization of phenylmenthyl ester 1e afforded 90percent of 13 with 86percent de.Cyclization of 31b provided 56percent of (+)-podocarpic acid precursor 32e with 82percent de.The direction of de was opposite in these two cases.Oxidative cyclization of α-methyl β-keto ester 44b gave a 1:1.6 mixture of 46b and 47b while α-propyl β-keto ester 44d produced a >10:1 mixture of 46d and 47d indicating that the extent and direction of de is dependent on the size of the α-substituent.The reaction proceeds through transition states 12 and 56 with large α-substituents and through transition states 19 and 57 with small α-substituents.The de depends on the double-bond substitution pattern as shown by the decreased de with 37b and 37d, and selectivity in the 5-exo cyclization of 64b, 65b, 70b, and 71b is low.
- Zhang, Qingwei,Mohan, Raju M.,Cook, Laura,Kazanis, Sophia,Peisach, Daniel,et al.
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p. 7640 - 7651
(2007/10/02)
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- Synthesis of Winterin from Podocarpic Acid
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Ozonolysis of a hydroquinone derived from podocarpic acid (1) gave the biologically active natural product winterin (11).Treatment of the quinone (12) with ozone bave a ring-contracted spiro furanone, the mechanism of formation of which is proposed.
- Bendall, Justin G.,Cambie, Richard C.,Grimsdale, Andrew C.,Rutledge, Peter S.,Woodgate, Peul D.
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p. 1063 - 1067
(2007/10/02)
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- 1,8-Diazabicycloundec-7-ene as a Mild Deprotective Agent for Acetyl Groups
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A simple acetyl cleavage is described.The method showed selective acetyl deprotection of polyfunctionalized molecules.
- Baptistella, Lucia Helena B.,Santos, Jose Fernando dos,Ballabio, Karin Cristina,Marsaioli, Anita Jocelyne
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p. 436 - 438
(2007/10/02)
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- SELECTIVE DEMETHYLATION OF ALIPHATIC METHYL ETHER IN THE PRESENCE OF AROMATIC METHYL ETHER WITH THE ALUMINUM CHLORIDE-SODIUM IODIDE-ACETONITRILE SYSTEM
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A combination system of aluminum chloride-sodium iodide-acetonitrile effects selective demethylation of aliphatic methyl ethers in the presence of aromatic methyl ether.KEYWORDS - demethylation; methyl ether; aluminum chloride; sodium iodide; hard acid; soft nucleophile
- Node, Manabu,Ohta, Keiichiro,Kajimoto, Tetsuya,Nishide, Kiyoharu,Fujita, Eiichi,Fuji, Kaoru
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p. 4178 - 4180
(2007/10/02)
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- Chemistry of the Podocarpaceae. LVIII An Improved Preparation of 12-Methoxypodocarpa-5,8,11,13-tetraen-19-ol
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An improved method for reducing methyl 12-methoxy-7-oxopodocarpa-5,8,11,13-tetraen-19-oate (1) to 12-methoxypodocarpa-5,8,11,13-tetraen-19-ol (2) with aluminium hydride is described.Reductions of 19-hydroxy-12-methoxypodocarpa-5,8,11,13-tetraen-7-one (3) and its methyl ether (4) are also examined.
- Cambie, Richard C.,Robertson, John D.,Rutledge, Peter S.,Woodgate, Paul D.
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p. 2687 - 2693
(2007/10/02)
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