AbstractThe syntheses of six new 2‐methyl‐6‐alkylamino‐5,8‐quinolinequinones, three 1,2,3,4‐tetrahydro‐5,8‐quinolinequinones, and 7‐(2′,6′,10′‐trimethylundecyl)‐6‐hydroxy‐5,8‐quinolinequinone are described as potential antimetabolites of coenzyme Q and as potential antimalarial agents. The six 2‐methyl‐6‐alkylamino‐5,8‐quinolinequinones were prepared by a six‐step synthesis. 2‐Methyl‐6‐methoxy‐8‐nitroquinoline was prepared from 2‐nitro‐4‐methoxyaniline and crotonaldehyde by a Skraup reaction. Raney nickel reduction gave 2‐methyl‐6‐metboxy‐8‐aminoquinoline, which upon diazotization followed by dithionite reduction yielded 2‐methyl‐6‐methoxy‐5,8‐diaminoquinoline. Subsequent dichromate oxidation gave 2‐methyl‐6‐methoxy‐5,8‐quinolinequinone, which yielded the corresponding 2‐methyl‐6‐alkylamino‐5,8‐quinolinequinone in good yield when treated with the appropriate alkylamine. The telrahydro‐5,8‐quinolinequinones were prepared by catalytic hydrogenation of the appropriate 5,8‐quinolinequinones at elevated H2pressure followed by air oxidation of the reduction product. 7‐(2′,6′,10′‐Trimethylundecyl)‐6‐hydroxy‐5,8‐quinolinequinone was synthesized by radical alkylation of 6‐hydroxy‐5,8‐quinolinequinone by thermal decomposition of di‐3,7,11‐trimethyldodecanoyl peroxide, which was prepared by a multistep procedure from farnesol. Of the five new 2‐methyl‐6‐alkylamino‐5,8‐quinoline‐quinones tested againstP. bergheiin mice (blood schizonticidal test), only 2‐methyl‐6‐cycloheptylamino‐5,8‐quinolinequinone was active (T‐C