- Catalytic stereoselective synthesis of β-digitoxosides: Direct synthesis of digitoxin and C1′-epi-digitoxin
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A mild and atom-economic rhenium(V)-catalyzed stereoselective synthesis of β-d-digitoxosides from 6-deoxy-d-allals has been described. This β-selective glycosylation was achieved probably because of the formation of corresponding α-digitoxosides disfavored by 1,3-diaxial interaction. In addition, this method has been successfully applied to the synthesis of digitoxin trisaccharide glycal for the direct synthesis of digitoxin and C1′-epi-digitoxin.
- Baryal, Kedar N.,Adhikari, Surya,Zhu, Jianglong
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p. 12469 - 12476
(2014/01/17)
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- Assembly of digitoxin by gold(I)-catalyzed glycosidation of glycosyl o-alkynylbenzoates
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Digitoxin, a clinically important cardiac trisaccharide, was assembled efficiently from digitoxigenin and 3,4-di-O-tert-butyldiphenylsilyl-d- digitoxosyl o-cyclopropylethynylbenzoate in 9 steps and 52% overall yield via alternate glycosylation and protecting group manipulation. The present synthesis showcases the advantage of the gold(I)-catalyzed glycosylation protocol in the synthesis of glycoconjugates containing acid-labile 2-deoxysugar linkages.
- Ma, Yuyong,Li, Zhongzhen,Shi, Hefang,Zhang, Jian,Yu, Biao
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experimental part
p. 9748 - 9756
(2012/01/04)
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- A direct comparison of the anticancer activities of digitoxin MeON-Neoglycosides and O-Glycosides
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Digitoxin is a cardiac glycoside currently being investigated for potential use in oncology; however, an investigation of anticancer activity as a function of oligosaccharide chain length has not yet been performed. We generated mono-, di-, and tri-O-digitoxoside derivatives of digitoxin and compared their activities to the corresponding MeON-neoglycosides. Both classes of cardenolide derivatives display comparable oligosaccharide chain length-dependent cytotoxicity toward human cancer cell lines. Further investigation revealed that both classes of compounds induce caspase-9-mediated apoptosis in non-small cell lung cancer cells (NCI-H460). Because O-glycosides and MeON-neoglycosides share a similar mode of action, the convenience of MeON-neoglycosylation could be exploited in future SAR work to rapidly survey large numbers of carbohydrates to prioritize selected O-glycoside candidates for traditional synthesis.
- Iyer, Anand Krishnan V.,Zhou, Maoquan,Azad, Neelam,Elbaz, Hosam,Wang, Leo,Rogalsky, Derek K.,Rojanasakul, Yon,O'Doherty, George A.,Langenhan, Joseph M.
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scheme or table
p. 326 - 330
(2010/12/18)
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- Recent advances in the synthesis of 2-deoxy-glycosides
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Glycosides of 2-deoxy-sugars, monosaccharides in which the hydroxyl group at C-2 is replaced with a hydrogen atom, occur widely in natural products and therefore have been the subject of intense synthetic activity. The report summarizes recent advances in this area, with a particular focus on work published since an earlier review on the topic, in 2000 (Marzabadi, C. H.; Franck, R. W. Tetrahedron 2000, 56, 8385-8417).
- Hou, Dianjie,Lowary, Todd L.
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scheme or table
p. 1911 - 1940
(2010/03/01)
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- De novo approach to 2-deoxy-β-glycosides: Asymmetric syntheses of digoxose and digitoxin
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A highly enantioselective and straightforward route to trisaccharide natural products digoxose and digitoxin has been developed. Key to this approach is the iterative application of the palladium-catalyzed glycosylation reaction, reductive 1,3-transposition, diastereoselective dihydroxylation, and regioselective protection. The first total synthesis of natural product digoxose was accomplished in 19 total steps from achiral 2-acylfuran, and digitoxin was fashioned in 15 steps starting from digitoxigenin 2 and pyranone 8β. This flexible synthetic strategy also allows for the preparation of mono- and disaccharide analogues of digoxose and digitoxin.
- Zhou, Maoquan,O'Doherty, George A.
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p. 2485 - 2493
(2008/02/02)
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- A stereoselective synthesis of digitoxin and digitoxigen mono- and bisdigitoxoside from digitoxigenin via a palladium-catalyzed glycosylation
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(Chemical Equation Presented) A convergent and stereocontrolled route to trisaccharide natural product digitoxin has been developed. The route is amenable to the preparation of both the digitoxigen mono- and bisdigitoxoside. This route featured the iterative application of the palladium-catalyzed glycosylation reaction, reductive 1,3-transposition, diastereoselective dihydroxylation, and regioselective protection. The natural product digitoxin was fashioned in 15 steps starting from digitoxigenin 2 and pyranone 8a or 18 steps from achiral acylfuran.
- Zhou, Maoquan,O'Doherty, George A.
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p. 4339 - 4342
(2007/10/03)
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- Convergent synthesis of digitoxin: Stereoselective synthesis and glycosylation of the digoxin trisaccharide glycal
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Tungsten-catalyzed alkynol cycloisomerization and iterative acid-catalyzed stereoselective glycosylations form the basis of a revolutionary new strategy for oligosaccharide synthesis. The method has been successfully applied to a highly convergent synthesis of Digitalis 2-deoxyglycosides.
- McDonald, Frank E.,Subba Reddy
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p. 3653 - 3655
(2007/10/03)
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- Dicarboxylic acid oxidation products
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What is disclosed is a dicarboxylic acid oxidation product of a immunologically reactive mono- or a polysaccharide having vicinal diols.
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