Boron trifluoride etherate → (3AS,6aR)-1,3-dibenzyltetrahydro-1H-furo(3,4-d)imidazole-2,4-dione

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Reaction Steps

To a solution of (4R,5S)-1,3-dibenzyl-5-methoxycarbonyl-2-oxoimidazolidine-4-carboxylic acid (mp., 149°-150° C., [α]36525 =+27.4° at c=1 in DMF, 1.84 g) in tetrahydrofuran (15 ml) were added sodium borohydride (226 mg) in small portions at -20° C., and boron trifluoride etherate (1.06 g). The obtained mixture was stirred at the same temperature for 1 hour and at room temperature for 3 hours, poured into ice-water (50 ml), stirred further at room temperature, adjusted to pH 9 with aqueous potassium carbonate and extracted twice with ethyl acetate (50 ml). Organic layer was washed with saturated aqueous sodium chloride solution, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was purified by chromatography on silica gel column to give (3aS,6aR)-1,3-dibenzylhexahydro-1H-furo[3,4-d]imidazole-2,4-dione (0.80 g). M.P., 114°-118° C. [α]D 20 =+59.8° (c=1, CHCl3).

Provenance & Evidence