Regio- and chemoselective reductive cleavage of 4,6-O-benzylidene-type acetals of hexopyranosides using BH3·THF–TMSOTf
作者:Katalin Daragics、Péter Fügedi
DOI:10.1016/j.tetlet.2009.03.194
日期:2009.6
cyclic acetals of carbohydrates undergo efficient reductive ring opening using BH3·THF and a catalytic amount of TMSOTf at room temperature. 4,6-O-Benzylidene-hexopyranosides afford the corresponding 4-O-benzyl ethers exclusively, in high yields. Other benzylidene-type acetals, such as naphthylmethylene and 4-methoxybenzylidene acetals are also cleaved with the same reagent. The conversions are highly regio-
Synthesis of glycosaminoglycan oligosaccharides. Part 5: Synthesis of a putative heparan sulfate tetrasaccharide antigen involved in prion diseases
作者:Katalin Daragics、Péter Fügedi
DOI:10.1016/j.tet.2010.08.004
日期:2010.10
The synthesis of the putative prion-associated heparan sulfate tetrasaccharide containing two d-glucuronic acid units is reported. Key to the synthesis were the differentiation of the N-acetylated and N-unsubstituted glucosamine units, the high-yielding glucosylation at O-4 of an N-acetyl-d-glucosamine derivative and the α-selective glycosylation of the 4′-OH group of a β-d-GlcpA-(1→4)-d-GlcpNAc disaccharide
报道了推定的含有两个d-葡萄糖醛酸单元的病毒相关的硫酸乙酰肝素四糖的合成。键合成为所述的分化Ñ -acetylated和ñ -未被取代的葡糖胺单元,在的O-4的高产葡糖Ñ乙酰基d -葡糖胺衍生物和的α选择性糖基化的4'-OH组具有双糖硫糖苷供体的β- d- Glc p A-(1→4)-d -Glc p NAc双糖结构单元。