反应详情

A solution of 3 g of 4,5-dihydro-imidazo-[1,2-a]-quinoxaline-2-methanol in 500 ml of chloroform and 9 g of manganese dioxide was refluxed with stirring for 6 hours and the mixture was filtered hot and concentrated. The mixuture was cooled and filtered to obtain 2.68 g of a imidazo-[1,2-a]-quinoxaline-2-methanol and imidazo-[1,2-a]-quinoxaline-2-carboxaldehyde mixture and the latter was chromatographed over silica gel. Elution with a 97.5% chloroform--2.5% methanol mixture yielded first 0.23 g of imidazo-[1,2-a]-quinoxaline-2-carboxaldehyde and then 1.42 g of imidazo-[1,2-a]-quinoxaline-2-methanol melting at 217°-220° C. Evaporation of the filtrate yielded 0.43 g of imidazo-[1,2-a]-quinoxaline-2-carboxaldehyde for a total yield of 0.66 g melting at 214°-215° C.

1. filtrationthe mixture was filtered hot
2. concentrationconcentrated
3. temperatureThe mixuture was cooled
4. filtrationfiltered