Studies on Pyrimidine Derivatives. VI. Synthesis of Thiazolo [5, 4-d] pyrimidines and Related Compounds. (6).

Abstract

By treatment with hydrogen peroxide 2-methyl-7-mercaptothiazolo [5, 4-d] pyrimidine was easily oxidized to the 7-hydroxy compound, and it was converted into the 7-chloro derivative. 7-Substituted (-OC₂H₅, -OC₆H₅, -NHC₂H₅ and -NHC₆H₅) 2-methylthiazolo-[5, 4-d] pyrimidines were synthesized from 7-chloro-2-methylthiazolo [5, 4-d] pyrimidine. 2, 7-Dimercaptothiazolo [5, 4-d] pyrimidine was prepared from 4, 6-dimercapto-5-amino-pyrimidine and potassium methylxanthate. The heating of 4-mercapto-5-amino-6-benzylthio-pyrimidine (XII) with formic acid or phosgene also resulted in ring closure to afford 7-benzylthio-thiazolo [5, 4-d] pyrimidine or 2-hydroxy-7-benzylthio-thiazolo [5, 4-d]-pyrimidine (XIV). Cleavage of (XIV) with sodium hydroxide solution was examined and (XII), the starting material, was recovered by the liberation of CO₂.