title: Synthesis of biantennary complex-type nonasaccharyl asn building blocks for solid-phase glycopeptide synthesis.
abstract: The biantennary complex-type N-glycans bearing LacNAc and LacdiNAc as the nonreducing end motif were synthesized in a protected form suitable to use in the Fmoc solid-phase peptide synthesis studies. Two approaches for the nonasaccharide synthesis were examined by taking advantage of the highly β-selective glycosylation with GlcNTCA (N-phenyl)trifluoroacetimidate. An earlier approach, which involved the reaction of the trisaccharide donor (Gal-GlcNTCA-Man) and trisaccharide acceptor (Man-GlcNPhth(2)-N(3)), produced a mixture of nonasaccharide isomers. On the other hand, mannosylation of the trisaccharide acceptor (Man-GlcNPhth(2)-N(3)) stereoselectively afforded the known pentasaccharide (Man(3)-GlcNPhth(2)-N(3)), which was reacted with the disaccharyl glycosyl donor (Gal-GlcNTCA or GalNTCA-GlcNTCA) to produce the desired nonasaccharide as a single stereoisomer. Selective dephthaloylation followed by N-acetylation furnished the GlcNAc(2) functionality. The resulting nonasaccharyl azides were condensed with Fmoc-Asp(OPfp)-OBu(t) or Fmoc-Asp(OPfp)-OPac in the presence of Ph(CH(3))(2)P and HOOBt. Finally, the Zn reduction and cleavage of the tert-butyl ester or Zn reduction alone produced the targeted nonasaccharyl Asn building blocks.
authors: Department of Applied Biochemistry, Institute of Glycoscience, Tokai University, 4-1-1 Kitakaname, Hiratsuka-shi, Kanagawa 259-1292, Japan.
authors: Masashi
authors: M
authors: Hagiwara
authors: Mizuki
authors: M
authors: Dohi
authors: Yuko
authors: Y
authors: Nakahara
authors: Keiko
authors: K
authors: Komatsu
authors: Yuya
authors: Y
authors: Asahina
authors: Akiharu
authors: A
authors: Ueki
authors: Hironobu
authors: H
authors: Hojo
authors: Yoshiaki
authors: Y
authors: Nakahara
authors: Yukishige
authors: Y
authors: Ito