Benzyloxycarbonylglycine → 4-Benzyloxycarbonyl-1,2,3,4-tetrahydropyrazin-2-one

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Reaction Steps

To a solution of N-benzyloxycarbonylglycine (10.5 g) and 2,2-diethoxyethylamine (7.33 g) in acetonitrile (50 ml) was added WSC hydrochloride (10.5 g) under ice-cooling, and the mixture was stirred at room temperature for 2 hours. The reaction solution was concentrated, and to the residue were added ethyl acetate and dilute hydrochloric acid. The organic layer was separated, washed with saturated and saturated brine, dried (MgSO4) and concentrated. To the residue were added p-toluenesulfonic acid (951 mg) and toluene (150 ml), and the mixture was refluxed for 30 minutes. The mixture was cooled, and to the reaction solution was added ethyl acetate. The mixture was washed with saturated sodium bicarbonate solution and saturated brine, dried (MgSO4) and concentrated. The resulting crystals were filtered, washed with ether and dried to give colorless crystals of the title compound (7.37 g).

Provenance & Evidence