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

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Reaction Conditions

Reaction Steps

0.673 g (2 mmol) of cis-1,3-dibenzyl-hexahydro-1H-furo[3,4-d]imidazole-2,4,6-trione and 0.435 g (2 mmol) of (-)-3,3-diphenyl-2-butanol ([α]36520 =-338.9° (1% in ethanol)) in 5 ml of toluene are heated under reflux for 6 hours in an apparatus standing under argon. After cooling 0.28 ml (2 mmol) of triethylamine and 5 ml of tetrahydrofuran are added thereto. The solution obtained is added dropwise within 30 minutes at 40° C. under argon to a solution of 4.8 ml of a 1 molar lithium borohydride solution in tetrahydrofuran (4.8 mmol) and the mixture is left to react at 40° C. for 14 hours. The excess hydride is decomposed at 10° C. with 5 ml of 3N HCl and the mixture is stirred at 60° C. for 30 minutes. The product obtained is isolated and purified as described in Example 2 and there is obtained 0.333 g of (3aS,6aR)-1,3-dibenzyl-dihydro-1H-furo[3,4-d]imidazole-2,4(3H,3aH)-dione. [α]D20 =+38.7° (1% in CHCl3), which corresponds to an optical purity of 62.4% e.e.

Provenance & Evidence