Nakamura, Hiroshi published the artcilePerchloric acid, a fluorogenic spray reagent for tryptophan, tryptamine, peptides containing tryptophan and other 3-substituted indoles, Application In Synthesis of 2642-37-7, the publication is Journal of Chromatography (1978), 152(1), 167-74, database is CAplus.
When silica gel plates containing 3-substituted indoles (e.g., 3-methylindole, indole-3-acetic acid), tryptophan derivatives, tryptamine, and tryptophan-containing peptides (e.g., H-Trp-Gly-OH, H-Pro-Trp-OH, H-Lys-Trp-Lys-OH) were sprayed with 70% HClO4, a strong yellow-orange fluorescence developed. Other indole derivatives did not give this fluorescence when sprayed with 70% HClO4. 3-Substituted indoles can be detected at 40-850 pmole by this method.
Journal of Chromatography published new progress about 2642-37-7. 2642-37-7 belongs to indole-building-block, auxiliary class Indole,Salt,Sulfonate,Inhibitor,Inhibitor, name is Potassium 1H-indol-3-yl sulfate, and the molecular formula is C8H6KNO4S, Application In Synthesis of 2642-37-7.
Referemce:
https://www.nature.com/articles/s41429-020-0333-2,
Preparation of Indole Containing Building Blocks for the Regiospecific Construction of Indole Appended Pyrazoles and Pyrroles