反应详情

To 3,4-diethoxycyclobut-3-ene-1,2-dione (1.20 mL, 8.10 mmol) in anhydrous DMF (10.0 mL) at room temperature was added a solution of 1-(5-nitropyridin-2-yl)piperazine (B-8) (1.926 g, 9.26 mmol) in anhydrous DMF (14.0 mL). The reaction mixture was stirred at room temperature for 3 h, and then diluted with absolute ethanol (40 mL) and methanol (30 mL). The yellow precipitate formed was filtered and washed with methanol (25 mL). The alcoholic filtrate was discarded, and the solid residue was dissolved in methylene chloride. The solution obtained was concentrated to give 3-ethoxy-4-(4-(5-nitropyridin-2-yl)piperazin-1-yl)cyclobut-3-ene-1,2-dione (C-9) as a yellow solid (1.93 g, 72% yield). MS (M+1): m/e 333. Nota: The presence of 1 equivalent 2-fluoroaniline or 2,6-dichloroaniline in the reaction mixture does not affect the course of the reaction in those conditions.

1. customThe yellow precipitate formed
2. filtrationwas filtered
3. washwashed with methanol (25 mL)
4. dissolutionthe solid residue was dissolved in methylene chloride
5. customThe solution obtained
6. concentrationwas concentrated