Imidazole → 1,3-Dibenzyltetrahydro-1H-thieno[3,4-d]imidazole-2,4-dione

Participants

Reaction Steps

Triethylamine (300 ml) and phosphorus pentasulfide (41 g) are added to a solution of 10.0 g of cis-1,3-dibenzyl-hexahydrofuro[3,4-d]imidazole-2,4-dione ([α]D20 + 62° (C = 2 in CHCl3)) and imidazole (21 g) in 150 ml of α-picoline. The mixture is stirred at room temperature for 1 hour and refluxed at about 100° C for 48 hours. Ethyl acetate (300 ml) and Celite-535 (5 g) are added to the reaction mixture cooled in an ice water bath, followed by addition of water (150 ml) and a saturated solution of sodium chloride (100 ml) and filtration of the resulting mixture. The organic layer is washed with water and concentrated in vacuo. The resulting residue is dissolved in 200 ml of toluene, followed by the addition of 7 % hydrochloric acid (100 ml) and zinc powder (10 g). The mixture is stirred and warmed at 60° to 65° C for 2 hours. The reaction mixture is cooled to room temperature and filtered off. The toluene layer is washed with water and concentrated in vacuo. The residue is triturated with ether, and the precipitate is filtered to give cis-1,3-dibenzyl-hexahydrothieno[-3,4-d]imidazole-2,4-dione (8.9 g, 85 %). M.P. 124° to 126° C. [α]D20 + 86° (C = 2 in CHCl3).

Provenance & Evidence