One-pot synthesis of sialo-containing glycosyl amino acids by use of an N-trichloroethoxycarbonyl-β-thiophenyl sialoside

Hiroshi Tanaka, Masaatsu Adachi, Takashi Takahashi

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101 Citations (Scopus)

Abstract

We describe an efficient synthesis of 2,6- and 2,3-sialyl T antigens linked to serine in a one-pot glycosylation. We first investigated the glycosidation of thiosialosides by varying the N-protecting group. Modification of the C-5 amino group of β-thiosialosides into the N-9-fluorenylmethoxycarbonyl, N-2,2,2-trichloroethoxycarbonyl (N-Troc), and N-trichloroacetyl derivatives enhanced the reactivity of these compounds towards glycosidation. Addition of a minimum amount of 3 Å molecular sieves was also effective in improving the yield of α-linked sialosides. Next, we conducted one-pot syntheses of the glycosyl amino acids by using the N-Troc sialyl donor. The N-Troc derivative can be converted into the N-acetyl derivative without racemization of the amino acids. Branched-type one-pot glycosylation, initiated by regioselective glycosylation of the 3,6-dihydroxy galactoside with the N-Troc-β-thiophenyl sialoside, provided the protected 2,6-sialyl T antigen in good yield. Linear-type one-pot glycosylation, initiated by chemoselective glycosylation of galactosyl fluoride with the N-Troc-β-thiophenyl sialoside, afforded the protected 2,3-sialyl T antigen in excellent yield. Both protected glycosyl amino acids were converted into the fully deprotected 2,6- and 2,3-sialyl T antigens linked to serine in good yields.

Original languageEnglish
Pages (from-to)849-862
Number of pages14
JournalChemistry - A European Journal
Volume11
Issue number3
DOIs
Publication statusPublished - 2005 Jan 21
Externally publishedYes

Keywords

  • Glycosyl amino acids
  • Glycosylation
  • Oligosaccharides
  • Sialic acids
  • Thioglycosides

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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