Diisopropylethylamine → 1,1-Bis(3-fluorophenyl)-N-[2-[cyclopropyl[(2-nitrophenyl)sulfonyl]amino]ethyl]-tetrahydro-3-oxo-3H-oxazolo[3,4-a]pyrazine-7(1H)-carboxamide

Participants

Reaction Steps

To a solution of N-(2-aminoethyl)-N-cyclopropyl-2-nitrobenzenesulfonamide (0.51 g, 1.8 mmol) and diisopropylethylamine (0.80 mL, 4.5 mmol) in tetrahydrofuran (20 mL) was added 4-nitrophenyl chloroformate (0.36 g, 1.8 mmol) with ice cooling, and the mixture was stirred at room temperature for 1 hour. 1,1-Bis(3-fluorophenyl)-hexahydro-3H-oxazolo[3,4-a]pyrazin-3-one (0.50 g, 1.5 mmol) was added thereto, and the mixture was stirred at room temperature overnight. To the reaction solution was added ethyl acetate, and the resulting mixture was sequentially washed with 1 N hydrochloric acid and a 1 N aqueous sodium hydroxide solution and water, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was purified with silica gel column chromatography (hexane:ethyl acetate=49:1 to ethyl acetate), and then crystallized from ethyl acetate-diethyl ether to obtain the title compound (0.24 g, yield 25%).

Provenance & Evidence