Abstract
The first synthesis of β‐L‐glycoside 17 of the tetrasaccharide β‐Ant‐(1 → 3)‐α‐L‐Rha__p‐(1 → 3)‐α‐L‐Rha__p‐(1 → 2)‐L‐Rha__p__ is described (Schemes 1–3). Its spacer can be functionalized to make it amenable to conjugation to proteins by different conjugation methods. The synthesis was performed in a stepwise manner starting from the aglycon‐bearing terminal saccharide with thioglycosides as glycosyl donors. To attach the upstream terminal anthrose residue, the assembled linker‐equipped trisaccharide was glycosylated with ethyl 4‐azido‐3‐O‐benzyl‐2‐O‐(bromoacetyl)‐4,6‐dideoxy‐1‐thio‐β‐D‐glucopyranoside (11). Further functionalization of the tetrasaccharide thus obtained, followed by deprotection gave the target substance 17. Synthesis of substructures of 17 equipped with the same spacer, namely β‐L‐Rha__p__‐1‐O‐(CH~2~)~5~COOMe (21), α‐L‐Rha__p__‐(1 → 2)‐β‐L‐Rha__p__‐1‐O‐(CH~2~)~5~COOMe (22), and α‐L‐Rha__p__‐(1 → 3)‐α‐L‐Rha__p__‐(1 → 2)‐β‐L‐Rha__p__‐1‐O‐(CH~2~)~5~COOMe (23), is also described (Scheme 4).