A Stereoselective Synthesis of Digitoxin and Digitoxigen Mono- and Bisdigitoxoside from Digitoxigenin via a Palladium-Catalyzed Glycosylation
作者:Maoquan Zhou、George A. O'Doherty
DOI:10.1021/ol061683b
日期:2006.9
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.
De Novo Approach to 2-Deoxy-β-glycosides: Asymmetric Syntheses of Digoxose and Digitoxin<sup>1</sup>
作者:Maoquan Zhou、George A. O'Doherty
DOI:10.1021/jo062534+
日期:2007.3.1
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
Thermal Degradation of Glycosides, I. Degradation of Typical Triterpenoid and Steroid Glycosides
作者:Ryuichi Higuchi、Yoichi Kitamura、Tetsuya Komori
DOI:10.1002/jlac.198619860405
日期:1986.4.15
The thermaldegradation of triterpenoid and steroidglycosides is described. By mere heating on a melting point apparatus, typicaltriterpenoid and steroidglycosides (involving cardiac and basic steroidglycosides) afford their aglycones and prosapogenins with the cleavage of their sugar–aglycone and sugar–sugar linkages similar to acid and enzymatic hydrolysis. Some genuine aglycones which were labile
A Direct Comparison of the Anticancer Activities of Digitoxin MeON-Neoglycosides and <i>O</i>-Glycosides
作者:Anand Krishnan V. Iyer、Maoquan Zhou、Neelam Azad、Hosam Elbaz、Leo Wang、Derek K. Rogalsky、Yon Rojanasakul、George A. O'Doherty、Joseph M. Langenhan
DOI:10.1021/ml1000933
日期:2010.10.14
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.