Hydrochloric Acid → (3aS,6aR)-hexahydro-1-[(R)-(1-phenylethyl)]-2-oxo-3-benzylthieno[3,4-d]imidazol-4-ylidene pentanoic acid

Participants

Reaction Conditions

Reaction Steps

159.8 mg (3.66 mmol) of sodium hydride and 1.7 ml of dimethyl sulfoxide were placed in a 25-ml round-bottom flask. The suspension was heated with stirring and under argon to 70° C. It was stirred for 40 minutes more until evolution of hydrogen was complete. The solution was cooled to room temperature and a solution of 801.5 mg (1.8 mmol) of (4-carboxybutyl)-triphenylphosphonium bromide in 1 ml of dimethyl sulfoxide was added. The dark red reaction mixture was stirred for 15 minutes and then added dropwise to a solution of 271 mg (0.77 mmol) of (3aS,6aR)-1-[(R)-(1-phenylethyl)]-3-benzyl-dihydro-1H-thieno-[3,4-d]-imidazol-2,4(3H,3aH)-dione in 2 ml of dimethyl sulfoxide and 0.2 ml of toluene. The reaction mixture was stirred for 2 hours at room temperature. Then 1 g of ice, 1 ml of conc, HCl and again 9 g of ice were added. After 5 minutes, 5 ml of water, 10 ml of benzene and 5 ml of ethyl acetate were added. Then the mixture was stirred for 1 hour at 60° C. The phases were separated. The brown organic phase was dried with 5 g of magnesium sulfate and separated with 4 preparative silica gel thin-layer plates (1 mm) by means of ethyl acetate. The product, (3aS,6aR)-hexahydro-1-[(R)-(1-phenylethyl)]-2-oxo-3-benzylthieno-[3,4-d]-imidazol-4-ylidene pentanoic acid, a colorless oil, was obtained in a yield of 38.2 mg (12 percent).

Provenance & Evidence