5-Isopropoxy-4-methyl-beta-carboline-3-carboxylic acid ethyl ester 89592-45-0 9H-Pyrido(3,4-b)indole-3-carboxylic acid, 4-methyl-5-(1-methylethoxy)-, ethyl ester Ethyl 4-methyl-5-(1-methylethoxy)-9H-pyrido(3,4-b)indole-3-carboxylate ZK 93 426 ZK 93426