Three quinoline alkaloids and two lignan lactones were isolated from Haplophyllum tuberculatum. Physicochemical and spectral evidence established the structures of two of the alkaloids as a new quinoldione, 3-(1′,1′-dimethylallyl)-3-(3″,3″-dimethylallyl)-1,2,3,4-tetrahydro-2,4-quinoldione and the known 4-(3′,3′-dimethylallyloxy)-3-(3″,3″-dimethylallyl)-2(1H)-quinolone. The former was shown to undergo facile [3,3]-sigmatotropic transformation into the latter. The remaining compounds were identified as the known Polygamain, kusunokinin and 1-methyl-2-n-nonyl-4(1H)-quinolone. © 1987.