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

Participants

Reaction Conditions

Reaction Steps

45.5 g (100 mmol) of cyclohexyl (4S,5R)-1,3-dibenzyl-5-chlorocarbonyl-2-oxo-4-imidazolidinecarboxylate (prepared according to Example 1) are dissolved in 50 ml of tetrahydrofuran. To the clear solution are added dropwise at 0° C. within 60 minutes 80 ml of a 1M lithium borohydride solution in tetrahydrofuran (80 mmol). The mixture is then stirred at 0° C. for a further 30 minutes. 100 ml of 1N hydrochloric acid are then cautiously added dropwise at 0° C. The mixture is then stirred at 70° C. for 30 minutes and subsequently concentrated in a rotary evaporator to 100 ml. Thereto there are added 200 ml of water and the mixture is left to crystallize at 0° C. for 18 hours. The crystallized-out crude product is filtered off under suction and washed neutral with water. After drying at 60° C. in vacuo for 4 hours, the crude product is dissolved in 100 ml of hot isopropanol and then left to crystallize at 0° C. for 18 hours. The product is then filtered off under suction and rinsed twice with 20 ml of ice-cold isopropanol each time. After drying at 60° C. in a water-jet vacuum for 6 hours, there are obtained 26.5 g of (3aS,6aR)-1,3-dibenzyldihydro-1H-furo[3,4-d]imidazole-2,4(3H,3aH)-dione with a melting point of 116°-117° C.

Provenance & Evidence