A SIMPLE METHOD FOR THE PREPARATION OF PYRIMIDO[4,5-d]|PYRIMIDINE-2,4(1H,3H)-DITHIONE DERIVATIVES

摘要

A facile and efficient two-step sequence for the preparation of 1,3-disubstituted pyrimido[4,5-d]pyrimidine-2,4(1H,3H)-dithiones starting with 4-chloro-6-methoxy-2-(methylsulfanyl)pyrimidine has been developed. Thus, the reaction of 4-chloro-5-lithio-6-methoxy-2-(methylsulfanyl)pyrimidine, generated by the treatment of the starting material with lithium diisopropylamide (LDA), with some aliphatic isothiocyanates gives N-alkyl-4-chloro-6-methoxy-2-(methylsulfanyl)pyrimidine-5-carbothioamides, which are then allowed to react with various isothiocyanates in the presence of sodium hydride to give the desired products. This method is applicable to the synthesis of 1,3-disubstituted 4-thioxo-3,4-dihydropyrimido[4,5-d]pyrimidin-2(lH)-ones using phenyl isocyanate in place of isothiocyanates.