Folate antagonists. 19. Synthesis and antimalarial effects of 6-(arylthio)-2,4-pteridinediamines

A series of 6-(arylthio)-2,4-pteridinediamines (IIIa) was prepared by allowing 6-chloro-2,4-pteridinediamine to react with the requisite benzenethiols in dimethyl sulfone at 190-200 degrees C. Attempts at oxidation to the corresponding sulfoxide (IIIb) or sulfone (IIIc) were unsuccessful. The compounds exhibited a spectrum of antibacterial activity similar to, but below the potency of, the related quinazolinediamines and pteridinediamines. Unlike these related types, however, they were devoid of antimalarial activity when tested against a normal drug-sensitive strain of Plasmodium berghei in mice by the parenteral route.