Marine natural products. VIII. Bioactive triterpene-oligoglycosides from the sea cucumber Holothuria leucospilota Brandt (2). Structure of holothurin A.
摘要:
海参Holothuria leucospilota BRANDT (=H. vagabunda SELENKA)的Cuvierian管中的主要羊毛甾烷型三萜寡糖苷holothurin A的化学结构已被阐明为3-O-[β-D-3-O-甲基葡萄糖吡喃糖苷-(1→3)-β-D-葡萄糖吡喃糖苷(1→4)-β-D-奎诺糖吡喃糖苷(1→2)-β-D-木糖吡喃糖苷]-holothurigenol 4'-O-硫酸钠(8),这一结论基于化学、物理化学和生物化学证据。Holothurin A (8)对应于holothurin B (6)的4"-O-[3'''-O-(β-D-3''''-O-甲基-葡萄糖吡喃糖苷)-β-D-葡萄糖苷],后者是同一种海参体壁中的主要寡糖苷。
Regioselective methylation of methyl glycopyranosides with diazomethane in the presence of transition-metal chlorides and of boric acid
作者:Evgeny V. Evtushenko
DOI:10.1016/s0008-6215(99)00044-0
日期:1999.3
Abstract Partial methylation of the methyl pyranosides of a number of pentoses, hexoses, 6-deoxyhexoses, methyl uronates and their methyl ethers with diazomethane in the presence of transition-metal chlorides and boric acid was studied. It was found for methyl glycosides of pentoses and 6-deoxyhexoses that tin(II), antimony(III), and titanium(IV) chlorides as well as boric acid promoted substitution
Regioselective benzoylation of glycopyranosides by benzoic anhydride in the presence of Cu(CF3COO)2
作者:Evgeny V. Evtushenko
DOI:10.1016/j.carres.2012.06.020
日期:2012.10
Benzoylation of methyl and benzyl glycopyranosides by benzoic anhydride in acetonitrile in the presence of copper(II) trifluoroacetate as a promoter has given monobenzoates with a good yield and high regioselectivity. The composition of monobenzoates depended both on a configuration of hydroxyl groups and on a configuration of aglycone. The simple syntheses of the monobenzoates of some glycosides are