Automated Fluorous-Assisted Solution-Phase Synthesis of β-12- 13- and 16-Mannan Oligomers

摘要

Automated solution-phase syntheses of β-1,2-, 1,3-, and 1,6-mannan oligomers have been accomplished by applying a β-directing C-5 carboxylate strategy. Fluorous-tag-assisted purification after each reaction cycle allowed the synthesis of short β-mannan oligomers with limited loading of glycosyl donor—as low as 3.0 equivalents for each glycosylation cycle. This study showed the capability of the automated solution-phase synthesis protocol for synthesizing various challenging glycosides, including use of a C-6 ester as a protecting group that could be converted under reductive conditions to a hydroxyl group for chain extension.