- A Short Total Synthesis of Benzophenanthridine Alkaloids via a Rhodium(III)-Catalyzed C-H Ring-Opening Reaction
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The biologically important naturally available benzophenanthridines were prepared efficiently in three steps with overall good yields. A new synthetic methodology involving a rhodium(III) catalyzed redox-neutral ring-opening of 7-azabenzonorbornadienes with aromatic aldoximes is developed to synthesize the target molecules. The developed C-H ring-opening reaction is highly diastereoselective and compatible with various sensitive functional group substituted aromatic aldoximes as well as substituted 7-azabenzonorbornadienes. The ring-opening products were transformed into highly sensitive 13,14-dehydrobenzo phenanthridine derivatives by HCl hydrolysis. Subsequently, 13,14-dehydrobenzophenanthridines were converted into biologically important benzophenanthridine alkaloids in the presence of DDQ. A possible reaction mechanism was proposed for the C-H ring-opening reaction and supported by the deuterium labeling studies.
- Aravindan, Narasingan,Jeganmohan, Masilamani
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p. 14826 - 14843
(2021/10/20)
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- Method for synthesizing oxime ether compound based on C-N bond breakage
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The invention relates to a method for synthesizing an oxime ether compound based on C-N bond breakage. The method comprises the step of making a compound shown in equation (1) and a compound show in equation (2) react in the presence of peroxide and an organic solvent to obtain the oxime ether compound as shown in formula (3), and reaction expression is shown in the description. According to the method, synthesis path is short, starting materials are simple, reaction condition is mild, the peroxide is cheap and free of pollution, substrate range is wide, products are easy to separate, and adaptability is high when reaction is amplified to be at the gram grade.
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Paragraph 0065; 0066; 0067
(2017/01/26)
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- Regiospecific synthesis of substituted 2-nitrobenzaldehydes from benzaldehydes through palladium-catalyzed chelation-assisted C-H nitration
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A regiospecific synthesis of substituted 2-nitrobenzaldehydes from substituted benzaldehydes has been developed that involves a three-step process with palladium-catalyzed chelation-assisted C-H nitration as the key step. In the process, O-methyl aldoxime serves as a removable directing group for the palladium-catalyzed ortho-nitration of substituted benzaldoximes and it can be removed in subsequent conversion of the resulting 2-nitrobenzaldoximes into 2-nitrobenzaldehydes.
- Zhang, Wei,Wu, Degui,Zhang, Jian,Liu, Yunkui
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p. 5827 - 5835
(2014/10/15)
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- Synthesis and biological evaluation of RON-neoglycosides as tumor cytotoxins
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Cardenolides such as digitoxin have been shown to inhibit cancer cell growth, to reduce cancer metastasis, and to induce apoptosis in tumor cells. Among the most potent digitoxin-based cytotoxins identified to date are MeON-neoglycosides generated via oxyamine neoglycosylation. Here, we report our studies of oxyamine neoglycosylation aimed at facilitating the elucidation of linkage-diversified digitoxin neoglycoside structure-activity relationships. We identified conditions suitable for the convenient synthesis of digitoxin neoglycosides and found that sugar structure, rather than RON-glycosidic linkage, exerts the strongest influence on neoglycoside yield and stereochemistry. We synthesized a library of digitoxin neoglycosides and assessed their cytotoxicity against eight human cancer cell lines. Consistent with previous findings, our data show that the structure of RON-neoglycosidic linkages influences both the potency and selectivity of digitoxin neoglycosides.
- Langenhan, Joseph M.,Endo, Matthew M.,Engle, Jeffrey M.,Fukumoto, Liane L.,Rogalsky, Derek R.,Slevin, Lauren K.,Fay, Lindsay R.,Lucker, Ryan W.,Rohlfing, James R.,Smith, Kyle R.,Tjaden, Anja E.,Werner, Halina M.
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experimental part
p. 2663 - 2676
(2012/01/07)
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- Ruthenium-catalysed conversion of oxime ethers into nitriles
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The conversion of oxime ethers into nitriles has been achieved under neutral conditions using Ru(CO)(PPh3)3H2 and the bidentate ligand Xantphos as the catalyst.
- Anand, Naveen,Owston, Nathan A.,Parker, Alexandra J.,Slatford, Paul A.,Williams, Jonathan M.J.
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p. 7761 - 7763
(2008/02/12)
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- HIV Integrase inhibitors
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The present invention relates to the inhibition of HIV integrase, and to the treatment of AIDS or ARC by administering compounds of the following formula, or a tautomer of said compound, or a pharmaceutically acceptable salt, solvate or prodrug thereof: wherein R1, R2 and B1 are as defined herein.
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- Stereoselective Synthesis of trans-2-Aryl-3-(2-pyridyl)aziridines from an α-Silyl Carbanion
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Five para-substituted benzaldehyde oxime O-methyl ethers (3) reacted with 2-(trimethylsilylmethyl)pyridine (1) in the presence of lithium di-isopropylamide (LDA) in tetrahydrofuran to give the corresponding trans-2-aryl-3-(2-pyridyl)aziridines (4) in high yield (80, 85, 60, 58, and 74percent, respectively), with small amounts of (Z)-1-amino-1-aryl-2-(2-pyridyl)ethenes (5), and N',N'-di-isopropylbenzamidines (7) as byproducts.The yields of compounds (4) and (5) and their ratio were considerably influenced by experimental conditions (especially molar ratio and the addition method of the reactants).When treated with LDA, compounds (3) were quantitatively converted into benzonitriles, which reacted with anion (2) to give enamines (5) after elimination of a trimethylsilyl group from the corresponding N-trimethylsilyl derivatives, or with additional LDA to give the benzamidine (7); aziridines (4) were not transformed into enamines (5) by the action of LDA.On the basis of these results, a reaction mechanism has been discussed for the formation of compounds (4).
- Konakahara, Takeo,Matsuki, Masayuki,Sugimoto, Shinji,Sato, Kenji
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p. 1489 - 1494
(2007/10/02)
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