Ethanol → (2R,3S,4R,5R)-2-(hydroxymethyl)-5-(2,5,6-trichlorobenzimidazol-1-yl)oxolane-3,4-diol

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Reaction Steps

To a solution of Na2CO3 (23.32 g, 220 mmol) in 440 mL of H2O were added successively 2.0 L of EtOH, 2.0 L of MeOH, and 105.5 g (220 mmol) of 42. The reaction mixture was stirred at room temperature for 2 hr. ACOH (26.44 mL, 462 mmol) was added and stirring was continued at room temperature for 20 min. The reaction mixture was filtered. The solid product was triturated with H2O (800 mL, 20 min), MeOH (500 mL, 30 min), and then recrystallized from EtOH/MeOH (1 L/1 L) to give 52.4 g of 45 as white crystals {2 crops, the 2nd crop (2.8 g) was obtained by evaporation of the mother liquid and recrystallization of the residue two more times from EtOH/MeOH}. Recrystallization was accomplished by dissolving the crude product in a minimum amount of boiling EtOH, diluting it immediately with an equal amount of hot MeOH and allowing it to slowly cool. The filtrate was evaporated and the residue was triturated with H2O (500 mL, 20 min), MeOH (500 mL, 30 min), and then recrystallized twice from EtOH/MeOH to give an additional 15.34 g of 45 {2 crops, the 2nd crop (1.95 g) was obtained by evaporation of the mother liquid and recrystallization of the residue two more times from EtOH/MeOH}. The total of 45 was 67.74 g (87%). MP: 166-168° C.

Provenance & Evidence