Synthesis of some 4-substituted 8-amino-6-methoxyquinolines as potential antimalarials.

The 4-vinyl, 4-ethyl, and three 4-[beta-(arylthio)ethyl] derivatives of primaquine and other 8-aminoquinoline antimalarial agents were prepared for antimalarial evaluation. 8-[(4'-Amino-1'-methylbutyl)amino]-4-ethyl-6-methoxyquinoline (4-ethylprimaquine), which showed activity approximately equal to that of primaquine against Plasmodia cynomolgi in Rhesus monkey, was the most active of the compounds tested. 4-Ethylprimaquine was also less toxic than primaquine, as measured in the Rane mouse screen.