Palladium-Catalyzed Stereoselective Formation of α- O -Glycosides (original) (raw)

Cl 3 C-CN DBU, CH 2 Cl 2 , 0 o C, 1h Preparation of glucal imidate 4. A 50 mL oven-dried Schlenk flask was charged with glucal 32 (480 mg, 2.58 mmol, 1 equiv) and CH 2 Cl 2 (15 mL). The solution was cooled to 0 o C, and trichloroacetonitrile (0.78 mL, 7.74 mmol, 3 equiv) and DBU (0.12 mL, 0.77 mmol, 0.3 equiv) were sequentially added to the solution. The resulting mixture was stirred at 0 o C for 1 h and concentrated. The residue was purified by silica gel flash chromatography (5/1, hexane/ethyl acetate with 1% triethylamine) to give 4 (644 mg, 76%) as a white solid.