To a stirred solution of 2-oxobenzothiazole (83 mg, 0.549 mmol) in DMF (3 ml) was added NaH (60% in mineral oil, 22 mg, 0.549 mmol) at room temperature. After 10 minutes, 1-[(2S,3R)-2-benzyloxy-5-methanesulfonyloxy-3-pentyl]imidazole-4-carboxamide in DMF (3 ml) was added and the resulting mixture was stirred for 6 hours at 60 to 70° C. The reaction mixture was poured into water (30 ml) and extracted with ethyl acetate. The organic layer was washed with brine, dried (sodium sulfate), and concentrated in vacuo. The residue was purified by silica gel (8 g) column chromatography eluting with chloroform/methanol (100:1 to 30:1) to give 1-[(2S,3R)-2-benzyloxy-5-(2-oxobenzothiazol-3-yl)-3-pentyl]imidazole-4-carboxamide (63 mg, 52.7%).
