(4R,6s)-4-phenyl-4,5,6,7-tetrahydro-3h-imidazo[4,5-c]pyridine-6-carboxylic acid
(3S)-1-phenyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole-3-carboxylic acid
(3S)-1-methyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole-3-carboxylic acid
(3S)-1-(2-nitrophenyl)-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole-3-carboxylic acid