Fig. 1.

Design and synthesis of partially esterified GalNAz. a Partially protected GalNAz with varied numbers of acetate or propionate. The greyscale chart shows the membrane permeability and ability of inducing artificial S-glycosylation of the unnatural monosaccharides. b Chemical synthesis of 2, 3 and 4. i. tert-butyldimethylsilyl chloride, pyridine, room temperature (R.T.), 20 h, 50%. ii. acetic anhydride, pyridine, 0 °C-R.T., overnight, 92%. iii. trifluoroacetic acid, dichloromethane, 0 °C-R.T., 1 h, 39%. iv. 2,2-dimethoxypropane, (±)-camphorsulfonic acid, acetone, 0–4 °C, 1 h, 48%. v. acetic anhydride, pyridine, 0 °C-R.T., overnight, 80%. vi. trifluoroacetic acid, H₂O, CH₃CN, 0 °C-R.T., 1 h, 70%. vii. propionic anhydride, pyridine, 0 °C-R.T., overnight, 82%. viii. trifluoroacetic acid, H₂O, CH₃CN, 0 °C-R.T., 1 h, 74%