Sulfuric Acid → 2,3,4,6-Tetra-O-benzyl-D-mannopyranose

Participants

Reaction Conditions

Reaction Steps

To a solution of (2R,3R,4S,5S,6S)-3,4,5-tris(benzyloxy)-2-((benzyloxy)methyl)-6-methoxytetrahydro-2H-pyran (28.0 g, 50.5 mmol, 1.0 equiv) in acetic acid (480 mL), was added 3M H2SO4 (120 mL, aqueous) at 0° C. The reaction was heated at 80° C. for 10 hours, cooled to room temperature, and then neutralized with saturated aqueous potassium carbonate solution. The mixture was then extracted with DCM (3×1000 mL). The combined organic layers were dried over anhydrous sodium sulfate, filtered, and concentrated in vacuo. The material thus obtained was purified by silica gel chromatography, eluting with 30% EtOAc in petroleum ether, to give (3S,4S,5R,6R)-3,4,5-tris(benzyloxy)-6-((benzyloxy)methyl)tetrahydro-2H-pyran-2-ol as a pale yellow oil (15.0 g, 54%). 1H NMR (300 MHz, DMSO-d6) δ 7.38-7.17 (m, 20H), 6.61 (d, J=4.4 Hz, 1H), 5.14-5.07 (m, 1H), 4.77 (t, J=8.5 Hz, 3H), 4.71-4.38 (m, 6H), 3.80 (dp, J=22.8, 9.1, 8.3 Hz, 3H), 3.68-3.53 (m, 2H). ESI (M+H2O) 558.2; calc for C34H36O6 540.3.

Provenance & Evidence