119623-89-1 α,α-Bis(ethoxycarbonyl)-1,2,5,8,9,10-hexahydro-2,5,8,10-tetraoxo-4,6-dipropylpyrido[3,2-g]quinoline-3,7-dipropanoic acid diethyl ester 119623-91-5 1,2,5,8,9,10-Hexahydro-2,5,8,10-tetraoxo-4,6-dipropylpyrido[3,2-g]quinoline-3,7-dicarboxylic acid diethyl ester