286018-83-5Relevant academic research and scientific papers
Dialkylphosphates as stereodirecting protecting groups in oligosaccharide synthesis
Yamada, Takeshi,Takemura, Kazunobu,Yoshida, Jun-Ichi,Yamago, Shigeru
, p. 7575 - 7578 (2008/02/01)
(Chemical Equation Presented) Double duty: A phosphoric ester at the C2 position in glycosyl donors directs the glycosylation to occur selectively at the anomeric carbon atom with complete 1,2-trans selectivity. Since the phosphoric ester can be removed to give the hydroxy function, this group serves as a stereodirecting protecting group in oligosaccharide synthesis.
Synthesis of N-acetylglucosamine containing Lewis A and Lewis X building blocks based on N-tetrachlorophthaloyl protection - synthesis of Lewis X pentasaccharide
Lay, Luigi,Manzoni, Leonardo,Schmidt, Richard R.
, p. 159 - 172 (2007/10/03)
Phenyl 6-O-benzyl-2-deoxy-2-tetrachlorophthalimido-1-thio-β-D-glucopyranoside (5a) and thexyldimethylsilyl 6-O-benzyl-2-deoxy-2-tetrachlorophthalimido-β-D-glucopyranoside (5b) gave with O-(2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl)trichloroacetimidate (8) in the presence of BF3*Et2O as catalyst exclusively lactosamine derivatives 7a and 7b, respectively, in high yields.Ensuing reaction with O-(3,4-di-O-acetyl-2-O-benzyl-α-L-fucopyranosyl)trichloroacetimidate (9) in the presence of TMSOTf as catalyst afforded LeX trisacharide intermediates 10a,b.With fucosyl donor 9 and 5a,b as acceptors in the presence of TMSOTf as catalyst glycosylation either at the 3-O or the 4-O was observed, thus leading to mixtures of disaccharides 11a/12a and 11b/12b, respectively; their reaction with 8 furnished LeX trisaccharide intermediates 10a,b and Lea trisaccharide intermediates 14a,b.Transformation of 10b into the corresponding trichlotoacetimidate 17 and reaction with lactose acceptor 19 in the presence of Zn(OTf)2 as catalyst gave protected LeX pentasaccharide intermediate 21, which on deprotection led to unprotected LeX pentasaccharide 1. - Keywords: Glycosylation; Trichloroacetimidates; Protection; N-tetrachlorophthaloyl; Disaccharide, Trisaccharide building blocks; Lewis X; Lewis A
