反应 #82019

反应方程式

5-nitro-6,7-dibromo-1,4-dihydro-2,3-quinoxalinedione

KOH

NH2OSO3H

( 5 )

5,6,7,8-Tetrafluoro-1,4-dihydro-2,3-quinoxalinedione

→

1-amino-5-nitro-6,7-dibromo-1,4-dihydro-2,3-quinoxalinedione

收率 64.0%

溶剂

water

water

反应条件

后处理

1. 1
   workup.STIRRINGThe mixture was stirred at 65° C. for 1 h
2. 2
   workup.WAITto stand at room temperature overnight
3. 3
   过滤the precipitate was collected by filtration at 50° C.
4. 4
   洗涤washed with distilled water (2 mL)
5. 5
   其他air dried at 50° C. overnight

实验过程

The procedure of Shin, S. C. and Lee. Y. Y., Taehan Hwahakhoe Chi 27 (5): 382-4 (1983) was adapted. To a stirred red solution of 5-nitro-6,7-dibromo-1,4-dihydro-2,3-quinoxalinedione (120 mg, 0.33 mMol) and 3N KOH (2 mL) in distilled water (5 mL) at 65° C. was dropwise added a colorless solution of NH2OSO3H (56 mg, 0.50 mMol) in distilled water (0.5 mL) with stirring, whereupon a yellow precipitate came out after 5 mins. The mixture was stirred at 65° C. for 1 h and allowed to stand at room temperature overnight, then the precipitate was collected by filtration at 50° C., washed with distilled water (2 mL), then air dried at 50° C. overnight, affording 80 mg (64%) of crude 1-amino-5-nitro-6,7-dibromo-1,4-dihydro-2,3-quinoxalinedione (free base Na+ by NMR, D2O), as a yellow amorphous solid (80% desired 1-amino-5-nitro-6,7-dibromo-1,4-dihydro-2,3-quinoxalinedione with 20% starting material by NMR). (It is not known if the reaction actually gave the 1-amino or 4-amino isomer.) A 80 mg sample of crude 1(4)-amino-5-nitro-6,7-dibromo-1,4-dihydro-2,3-quinoxalinedione (0.211 mMol) was dissolved into distilled water (10 mL) at 50° C., then acidified with AcOH to pH=5. After the insoluble material was removed by filtration, it was heated at 60°-70° C. until a clear solution was obtained, then slowly cooled, and a yellow precipitate came out. The precipitate was crystallized from hot EtOH, collected by filtration, and washed with cold ethanol (2 mL), then dried in the air at 60° C. for 4 h, affording 57 mg (45.6%) of pure 1(4)-amino-5-nitro-6,7-dibromo-1,4-dihydro-2,3-quinoxalinedione (free base H). NH2OSO3H (40 mg, 0.35 mMol) was added to the mother liquid, and allowed to react at 65°-70° C. for 30 min to give a second crop of pure 1(4)-amino-5-nitro-6,7-dibromo-1,4-dihydro-2,3-quinoxalinedione (26 mg, 21%), using the same procedure as above. The total yield is 66%. Mp was measured: the color of 1(4)-amino-5-nitro-6,7-dibromo-1,4-dihydro-2,3-quinoxalinedione changed to dark yellow at 301° C.; the decomposition of 1(4)-amino-5-nitro-6,7-dibromo-1,4-dihydro-2,3-quinoxalinedione is obvious at 310° C. and it melted to a black liquid at 320°-1° C. IR (KBr, cm-1): 3414; 3211; 1745; 1728; 1682; 1631; 1546. NMR (1H, DMSO-d6): δ 5.832 (s, 2H); 8.047 (s, 1H); 12.565 (s, 1H). HRMS: calcd for C8H4N4O4Br2 (M+)m/z: 377.8613; found: 377.8583.

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