Methyl 2,3,6-Tri-O-benzoyl-alpha-D-galactopyranoside

Conditions: temp:-30.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 3 g of methyl 2,3,6-tri-O-benzoyl-α-D-galactopyranoside 57 (Reist et al., J. Org. Chem 1965, 30, 2312) are introduced into dichloromethane and cooled to −30° C. Then 3.06 ml of [bis(2-methoxyethyl)amino]sulfur trifluoride (BAST) are added dropwise. The reaction solution is warmed to room temperature and stirred overnight. The mixture is diluted with dichloromethane, and the organic phase is extracted with H2O, NaHCO3 solution and saturated NaCl solution. The organic phase is dried over Na2SO4 and concentrated. The crude product is crystallized from ethyl acetate and heptane. 1.95 g of 58 are obtained as a colorless solid. C28H25FO8 (508.51) MS (ESI+) 526.18 (M+NH4+). Alternatively, the reaction can also be carried out using 2.8 eq. of diethylaminosulfur trifluoride (DAST); in this case, the reaction solution is refluxed for 18 h after the addition. The working up takes place in analogy to the above description. The reaction solution is warmed to room temperature the organic phase is extracted with H2O, NaHCO3 solution and saturated NaCl solution The organic phase is dried over Na2SO4 concentrated The crude product is crystallized from ethyl acetate and heptane