反应 #1703

反应方程式

water

sodium hydride

ethyl 4,5-dihydro-4-oxo-10H-imidazo[1,2-a]indeno[1,2-e]pyrazine-2-carboxylate

isoamyl nitrite

→

10-hydroxyimino-4,5-dihydro-4-oxo-imidazo[1,2-a]indeno[1,2-e]pyrazine-2-carboxylic acid

溶剂

dimethyl sulphoxide

acetic acid

反应条件

后处理

1. 1
   温度is maintained below 20° C
2. 2
   其他The precipitate formed
3. 3
   过滤is filtered off
4. 4
   洗涤washed with water, with acetone
5. 5
   干燥with methanol and finally dried under reduced pressure (1 mm Hg; 0.13 kPa)

实验过程

0.34 g of sodium hydride is added to 1 g of ethyl 4,5-dihydro-4-oxo-10H-imidazo[1,2-a]indeno[1,2-e]pyrazine-2-carboxylate in solution in 20 ml of anhydrous dimethyl sulphoxide, while the temperature of the reaction mixture is maintained below 20° C. 0.44 ml of isoamyl nitrite is then added and stirring is continued for 18 hours at the same temperature. The reaction mixture is then poured into iced water and the solution is acidified with 15 ml of acetic acid. The precipitate formed is filtered off, washed with water, with acetone and then with methanol and finally dried under reduced pressure (1 mm Hg; 0.13 kPa) to produce 0.25 g of 10-hydroxyimino-4,5-dihydro-4-oxo-imidazo[1,2-a]indeno[1,2-e]pyrazine-2-carboxylic acid in the form of a brown powder whose melting point is higher than 260° C. (1H spectrum in DMSO, T=300K, δ in ppm (200 MHz), mixture of the syn and anti isomers: Major isomer: between 7.30 and 7.50 (2H, m, CH arom.), 7.62 (1H, s, CH arom.), 7.82 (1H, d, J=7 Hz, CH arom.), 8.00 (1H, s, CH arom.), 8.20 (1H, d, J=7 Hz, CH arom.), 12.7 (1H, s, NH), 13.0 (1H, s, OH), Minor isomer: between 7.30 and 7.50 (2H, m, CH arom.), 7.51 (1H, s, CH arom.), 7.70 (1H, d, J=7 Hz, CH arom.), 7.88 (1H, d, J=7 Hz, CH arom.), 8.58 (1H, s, CH arom.), 12.7 (1H, s, NH), 13.2 (1H, s, OH)).

来源