Toluene-4-sulfonate1-[2-(1H-indol-3-yl)-2-methoxycarbonyl-ethyl]-4-methyl-pyridinium;
Toluene-4-sulfonate3-ethyl-1-[2-(1H-indol-3-yl)-1-methoxycarbonyl-ethyl]-pyridinium;
Toluene-4-sulfonate3-acetyl-1-[2-(1H-indol-3-yl)-1-methoxycarbonyl-ethyl]-pyridinium;
Toluene-4-sulfonate1-[2-(1H-indol-3-yl)-2-methoxycarbonyl-ethyl]-4-methoxycarbonylmethyl-pyridinium;
rac-4-<2-(Formamido)phenyl>-2-hydroxy-4-oxobuttersaeure