Synthesis of isoxazolo[4,5-e][1,4]diazepin-5-ones from 5-acyl-4-(haloacetylamino)isoxazoles

Treatment of 5-benzoyl-4-(iodoacetylamino)isoxazoles with alcoholic ammonia leads to isoxazolo[4,5-e][1,4]diazepin-5-ones, whereas the analogous chloroacetylamino derivatives are converted into a mixture of the deacylated 4-aminoisoxazoles and isoxazolo- [4,5-d]pyrimidines.