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

Participants

Reaction Steps

A solution of ethyl chloroformate (0.54 g) in tetrahydrofuran (2 ml) wasd added dropwise to a mixture 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), triethylamine (0.51 g) and tetrahydrofuran (10 ml) at -5° C. The mixture was stirred at the same temperature for 30 minutes. Precipitated triethylamine hydrochloride was filtered off and the filtrate was added dropwise to a solution of sodium borohydride (0.24 g) in 90% aqueous tetrahydrofuran (10 ml) at -15° C. After reacting, the mixture was acidified with diluted hydrochloric acid and extracted with ethyl acetate. The extract was concentrated under reduced pressure and 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 (1.04 g). M.P., 114°-117° C. [α]D20 =+59.0° (c=1, CHCl3).

Provenance & Evidence