1 PD6 5-amino-1-butyl-7-phenyl-1,6-naphthyridin-4(1h)-one 1.000 2 3GX 1-methyl-7-phenyl-2,3,4,6-tetrahydro-1,6-naphthyridin-5(1h)-one 0.739 3 E9L (1s)-1-methyl-7-(4-methylphenyl)-5-oxo-1,5-dihydro-1,6-naphthyridin-1-ium 0.708