Hydrochloric Acid → (3AS,6aR)-1,3-dibenzyltetrahydro-1H-furo(3,4-d)imidazole-2,4-dione

Participants

Reaction Steps

To a mixture of sodium borohydride (0.55 g) and 99.5% ethanol (20 ml) were added dropwise a solution of (4R,5S)-1,3-dibenzyl-5-methoxycarbonyl-2-oxoimidazolidine-4-carboxylic acid (mp., 149°-150° C., [α]36525 =-27.7° at c=1 in DMF, 2.00 g) in 99.5% ethanol (30 ml) at 0°-5° C. and a solution of anhydrous calcium chloride (0.80 g) in 99.5% ethanol (8 ml) at the same temperature. The obtained mixture was allowed to warm up to room temperature and to react at the same temperature for 18 hours under stirring. Then, 1N hydrochloric acid was added dropwise to the reaction mixture. The solvent was removed from the mixture at 50°-55° C. under reduced pressure. The residue was shaken with chloroform (50 ml) and water (50 ml). Chloroform layer was washed successively with 5% aqueous sodium hydrogen carbonate and water, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was treated with ether (10 ml), filtered and dried to give (3aS,6aR)-1,3-dibenzylhexahydro-1H-furo[3,4-d]imidazole-2,4-dione (1.43 g). M.P., 116°-117° C. [α]D25 =+60.9° (c=1, CHCl3).

Provenance & Evidence