Abstract
Heating of the sodium salt of 4-amino-5-acylamino-6-mercaptopyrimidine results in the formation of a purine derivative but its heating with dilute hydrochloric or sulfuric acid was found to give thiazolo[5, 4-d]pyrimidine derivatives. 5-Amino-6-mercaptopyrimidine derivatives react with nitrile to form thiazolo[5, 4-d]pyrimidine derivatives, while they react with monochloroacetic acid to form pyrimido[4, 5-b][1, 4]thiazine derivatives, and with nitrous acid to form thiadiazolo[5, 4-d]pyrimidine derivatives.
