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Synthesis of Protected Hexp‐(1 → 4)‐β‐ D ‐Glc p NAc‐(1 → 2)‐α‐ D ‐Man p ‐(1 → O)(CH 2 ) 7 CH 3 sequences (hex = β‐ D ‐Glc, 4‐deoxy‐4‐fluoro‐β‐ D ‐Gal, or 4‐deoxy‐β‐ D ‐Gal) Using a Glc–GlcNPhth Donor, Eventually Fluorinated or Deoxygenated at the Oligosaccharide Level
Author(s) -
van Dorst Johannes A. L. M.,
Voskamp Anton F.,
Kamerling Johannis P.,
Vliegenthart Johannes F. G.
Publication year - 1997
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199719970627
Subject(s) - chemistry , trisaccharide , halogenation , disaccharide , acetal , ring (chemistry) , stereochemistry , acetylation , medicinal chemistry , organic chemistry , biochemistry , gene
Three trisaccharide derivatives of the type β‐ D ‐Hex p ‐(1 → 4)‐β‐ D ‐Glc p NAc(1 → 2)‐α‐ D ‐Man p ‐(1 → O)(CH 2 ) 7 CH 3 have been synthesized, with Hex being either glucose ( 15 ), 4‐deoxy‐4‐fluorogalactose ( 20 ), or 4‐deoxygalactose ( 27 ). These trisaccharides have been designed for the study of the acceptor specificity of glycosyltransferases involved in termination of N ‐acetyllactosamine‐type N‐glycans. Allyl (2‐ O ‐acetyl‐3,6‐di‐ O ‐benzyl‐β‐ D ‐glucopyranosyl)‐(1 → 4)‐3,6‐di‐ O ‐benzyl‐2‐deoxy‐2‐phthalimido‐β‐ D ‐glucopyranoside ( 10 ) was synthesized by condensation of 2,4,6‐tri‐ O ‐acetyl‐3‐ O ‐benzyl‐α‐ D ‐glucosypanosyl trichloroacetimidate with allyl 3,6‐di‐ O ‐benzyl‐2‐deoxy‐2‐phthalimido‐β‐ D ‐glucopyranoside, followed by 4′,6′‐de‐ O ‐acetylation, 4′,6′‐ O ‐benzylidenation ( 8 ), and specific acetal ring opening. Acetylation or inverted fluorination of 10 , followed by deallylation and imidation, gave suitable disaccharide donors which were each condensed with octyl 3,4,6‐tri‐ O ‐benzyl‐α‐ D ‐mannopyranoside ( 14 ) to afford the fully protected trisaccharides 15 and 20 . Deallylation and imidation of 8 , followed by coupling to 14 and subsequent specific acetal ring opening, triflation, halogenation, and reductive dehalogenation gave the protected 4″‐deoxytrisaccharide.