Studies on Pyrimidine Derivatives. VII. Synthesis of Thiazolo [5, 4-d] pyrimidines and Related Compounds. (7)

抄録

5-Chlorothiazolo [5, 4-d] pyrimidine was prepared from 2-chloro-4-mercapto-5-aminopyrimidine (I) and ethyl orthoformate. Ring closure occurred by the reaction of (I), 2, 4-dimercapto-5-aminopyrimidine, 4-mercapto-5-amino-6-chloropyrimidine, or 4-mercapto-5-aminopyrimidine with phosgene, and the corresponding 2-hydroxythiazolo [5, 4-d] pyrimidine derivatives (5-chloro-, 5-mercapto-, 7-chloro-) and 2-hydroxythiazolo [5, 4-d] pyrimidine itself were respectively obtained. When dimercaptothiazolo [5, 4-d] pyrimidines possessing substituents in 2-and 5-positions or in 2-and 7-, were reacted with one mole of ethyl bromide in alkali, substitution occurred only in positions 5-and 7-of the thiazolo [5, 4-d] pyrimidine ring. 2-Thiocyanothiazolo [5, 4-d]-pyrimidine reacted with sodium ethoxide to give 2-mercaptothiazolo [5, 4-d] pyrimidine. Thiazolo [5, 4-d] pyrimidine was obtained by desulfurization of 2-mercaptothiazolo [5, 4-d]-pyrimidine with Raney nickel.