反应详情

A mixture of the anhydride of cis-1,3-dibenzyl-2-oxo-imidazolidine-4,5-dicarboxylic acid (50.0 g), (R)-1-phenethylamine (18.9 g) and toluene (200 ml) is stirred and refluxed at 105° to 110° C for 2 hours. The toluene is distilled off, and the resulting residue is heated at 210° to 220° C for 1 hour. cis-1,3-Dibenzyl-5-[(R)-1-phenethyl]-hexahydropyrro[3,4-d]imidazole-2,4,6-trione left as the residue is dissolved in ethanol (750 ml), to which 97 % sodium borohydride (23.3 g) is added below 10° C. The mixture is stirred at room temperature for 16 hours. After the reduction is completed, the mixture is neutralized by the addition of acetic acid (35 ml) and concentrated in vacuo. The residue which contains cis-1,3-dibenzyl-4-[N-(R)-1-phenethylcarbamoyl]-5-hydroxymethyl-tetrahydroimidazol-2-one is heated under reflux with n butanol (500 ml) and 35 % hydrochloric acid (100 ml) for 2 hours. After the reaction is over, the mixture is cooled to room temperature. The n-butanol layer is separated, washed with water and concentrated in vacuo. The precipitate is collected by filtration to yield cis-1,3-dibenzyl-hexahydrofuro[3,4-d]imidazole-2,4-dione (44.6 g, 93.1 %). M.P. 96° to 101° C. [α]D25 + 13.8° (C = 2 in CHCl3). IR (Nujol) 1775, 1690 to 1700 cm-1 (C = 0).

1. temperaturerefluxed at 105° to 110° C for 2 hours
2. distillationThe toluene is distilled off
3. temperaturethe resulting residue is heated at 210° to 220° C for 1 hour
4. waitcis-1,3-Dibenzyl-5-[(R)-1-phenethyl]-hexahydropyrro[3,4-d]imidazole-2,4,6-trione left as the residue
5. dissolutionis dissolved in ethanol (750 ml), to which 97 % sodium borohydride (23.3 g)
6. additionis added below 10° C
7. stirringThe mixture is stirred at room temperature for 16 hours
8. additionthe mixture is neutralized by the addition of acetic acid (35 ml)
9. concentrationconcentrated in vacuo
10. temperatureis heated
11. temperatureunder reflux with n butanol (500 ml) and 35 % hydrochloric acid (100 ml) for 2 hours
12. customThe n-butanol layer is separated
13. washwashed with water
14. concentrationconcentrated in vacuo
15. filtrationThe precipitate is collected by filtration