1-Ethyl-3-(3'-dimethylaminopropyl)carbodiimide → 4-Benzyloxycarbonyl-1-(tert-butoxycarbonylamino)-2-oxo-1,2,3,4-tetrahydropyrazine

Participants

Reaction Steps

A solution of tert-butoxycarbonylhydrazine (3.96 g) and N-benzyloxycarbonyl-N-(2,2-diethoxyethyl) glycine (9.76 g) in acetonitrile (100 ml) was treated with WSC (5.75 g) and stirred at room temperature for 15 hours. The reaction mixture was concentrated to obtain a residue, which was partitioned between ethyl acetate and water, and then the organic phase was washed with water, aqueous sodium bicarbonate, aqueous solution of citric acid and brine, dried and then concentrated. The residue obtained was dissolved in toluene (200 ml), combined with p-toluenesulfonic acid hydrate (285 mg) and then stirred at 100° C. for 90 minutes. The reaction mixture was washed with saturated aqueous sodium bicarbonate and brine, dried and then concentrated. The residue thus obtained was purified by a column chromatography on a silica gel (hexane:ethyl acetate=3:2) to obtain 4-benzyloxycarbonyl-1-(tert-butoxycarbonylamino)-2-oxo-1,2,3,4-tetrahydropyrazine (1.84 g) as a colorless oil.

Provenance & Evidence