Synthesis of β‐<scp>D</scp>‐Gal<i>p</i>‐(1⇄4)‐β‐<scp>D</scp>‐Glc<i>p</i>NAc‐(1⇄2)‐α‐<scp>D</scp>‐Man<i>p</i>‐(1⇄O)(CH₂)₇CH₃ Mimics to Explore the Substrate Specificity of Sialyltransferases and <i>trans</i>‐Sialidases

Abstract

Abstract Eleven trisaccharide octyl glycosides related to the N‐glycan sequence β‐ D ‐Gal p ‐(1⇄4)‐β‐ D ‐Glc p NAc‐(1⇄2)‐α‐ D ‐Man p ‐(1⇄O)(CH 2 ) 7 CH 3 ( 1 ) designed for detailed exploration of the acceptor specificity of α‐2,3‐ and α‐2,6‐sialyltransferases as well as trans ‐sialidases, have been synthesised: β‐ D ‐Gal p ‐(1⇄4)‐β‐ D ‐Glc p NPr‐(1⇄2)‐α‐ D ‐Man p ‐(1⇄O)(CH 2 ) 7 CH 3 ( 2 ), β‐ D ‐Fuc p ‐(1⇄4)‐β‐ D ‐Glc p NR‐(1⇄2)‐α‐ D ‐Man p ‐(1⇄O)(CH 2 ) 7 CH 3 ( 3 , R = Ac; 4 , R = Pr), 6‐amino‐6‐deoxy‐β‐ D ‐Gal p ‐(1⇄4)‐β‐ D ‐Glc p NR‐(1⇄2)‐α‐ D ‐Man p ‐(1⇄O)(CH 2 ) 7 CH 3 ( 5 , R = Ac; 6 , R = Pr), 2‐deoxy‐β‐ D ‐Gal p ‐(1⇄4)‐β‐ D ‐Glc p NR‐(1⇄2)‐α‐ D ‐Man p ‐(1⇄O)(CH 2 ) 7 CH 3 ( 7 , R = Ac; 8 , R = Pr), β D ‐Gal p NR 1 ‐(1⇄4)‐β‐ D ‐Glc p NR‐(1⇄2)‐α‐ D ‐Man p ‐(1⇄O)(CH 2 ) 7 CH 3 ( 9 , R = R 1 = Ac; 10 , R = R 1 = Pr; 11 , R = Ac, R 1 = Pr; 12 , R = Pr, R 1 = Ac). All trisaccharides were obtained by condensation of suitably modified glycosyl donors based on imidates or thioglycosides with the single disaccharide acceptor octyl (3,6‐di‐ O ‐benzyl‐2‐deoxy‐2‐phthalimido‐β‐ D glucopyranosyl)‐(1⇄2)‐3,4,6‐tri‐ O ‐benzyl‐α‐ D ‐mannopyranoside, followed by deprotection. For the trisaccharides containing an N ‐acylated glucosamine as well as an N ‐acylated galactosamine unit, use was made of a combination of N ‐phthaloyl and N ‐dimethylmaleoyl protection. (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2003)