The route to indole-3-acetaldehyde by simple NaOCl oxidation of tryptophan has always intrigued me since it was posted here a couple of years ago. Granted, the dilution and amount of solvent used is huge, but in practice this takes only more time in the work-up, a price that is most willingly paid for what could be an OTC route to the dialkyltryptamine of choice. It is astounding that nobody has reported trials for what looks like a very straightforward route, even if indole-3-acetaldehyde is an unstable critter, it has worked for at least 2 different groups in the literature.
https://www.thevespiary.org/rhodium/Rhodium/pdf/indole-3-acetaldehyde.pdf
Two trials were made
(by a famous Hungarian actor who appeared to me in a vivid dream ) using the above procedure, but substituting toluene for carcinogenic and thus restricted benzene.
From the first trial, after evaporating the red toluene extract in vacuo (fridge compressor, +- 50°C), a thick red oil containing orange solid material was obtained, that failed to produce a bisulfite adduct. This was, however, chalked up to inefficient stirring.
In the second trial, heavy overhead stirring was used, so that an almost uniform emulsion was attained during the whole process. Again, the toluene layer was deep red in color, and after concentrating the organic layer in vacuo using the same fridge compressor, a dark red oily residue was obtained instead of a yellow one like described in the above article. This formed a greyish brown solid upon treatment with a saturated bisulfite solution, which was washed several times with water. This was added to a warm sodium carbonate solution, stirred for 20 minutes and extracted with DCM.
The solid should have been washed with alcohol too, but that was forgotten by mistake.
After evaporation of the DCM, about 2 grams of a red oily residue was again obtained. This was diluted with ethanol, an excess of aqueous dimethylamine solution (containing 2 grams Me
2NH) was added and the mixture was stirred for an hour in a cold water bath. A gram of NaBH
4 was added in small portions while cooling the mixture in a cold water bath, stirring was continued for an hour, and the mixture was acidified with acetic acid.
Standard A/B work-up, extraction of the basic mother-liquor with DCM and evaporation of the solvent yielded... nothing but an unknown red-coloured solid which was certainly not the desired compound
.
Maybe it would help to add some kind of polymerization-inhibitor to the organic layer before adding the hypochlorite solution?