The Asymmetric Syntheses of Methyl <small>D</small>-Digitoxoside, <small>L</small>-Oleandrose and <small>L</small>-Cymarose from Methyl Sorbate, an Achiral Precursor
addition product (+)-(3S,4S,5R)-9 possessing a 3,4-cis-dihydroxy-δ-lactone in 78% overall yield from (4S,5R)-4. The obtained (+)-(3S,4S,5R)-9 was subsequently converted to methyl D-digitoxoside (pyranoside) (12) in 13% overall yield and methyl D-digitoxoside (furanoside) (12) in 20% overall yield. The reaction of benzyl-osmundalactone (4R,5S)-3 and MeOH in the presence of Amberlyst A-26 as a basic catalyst
C 21 steroidal glycosides from the roots of Cynanchum saccatum
作者:Mi Zhang、Li-Li Rao、Cheng Xiang、Bao-Cai Li、Peng Li
DOI:10.1016/j.steroids.2015.05.009
日期:2015.9
Eight new C-21 steroidal glycosides, named cynsaccatols A-H (1-8), along with two known analogs (9-10), were isolated from the roots of Cynanchum saccatum. Their structures were determined on the basis of detailed spectroscopic analysis, as well as HRESIMS. All compounds (1-10) were tested for their cytotoxicity in vitro using three human cancer cell lines (HepG2, Hela and U251), and compounds 1, 4, 5, 9, 10 showed weak inhibitory activities against different cell lines, respectively. (C) 2015 Elsevier Inc. All rights reserved.
Oxidative Cleavage of 3-Alkoxy-2,5-dihydrofurans and its Application to the De Novo Synthesis of Rare Monosaccharides as Exemplified byL-Cymarose
作者:Malte Brasholz、Hans-Ulrich Reissig
DOI:10.1002/anie.200604078
日期:2007.2.26
Alkoxyallene-Based De Novo Synthesis of Rare Deoxy Sugars: New Routes to L-Cymarose, L-Sarmentose, L-Diginose and L-Oleandrose
作者:Malte Brasholz、Hans-Ulrich Reißig
DOI:10.1002/ejoc.200900450
日期:2009.7
Starting from lithiated methoxyallene and lactaldehyde derivatives, the four rare 2,6-dideoxy-hexoses L-cymarose, L-sarmentose, L-diginose and L-oleandrose were synthesized in a stereodivergent fashion. Key steps towards these four target monosaccharides were the oxidative ring openings of allene-derived 2,5-dihydrofurans, diastereoselective carbonyl reductions as well as face-selective hydrogenation