Analytical characterisation of the routes by thermolytic decarboxylation from tryptophan to tryptamine using ketone catalysts, resulting in tetrahydro-beta-carboline formation.
N-Alkylated tryptamines have complex psychoactive properties. Routes for clandestine synthesis are described on Internet websites one of which involves the thermolytic decarboxylation of tryptophan to tryptamine as a precursor to psychoactive compounds. High boiling solvents and ketone catalysts have been employed to facilitate the decarboxylation of tryptophan. The present study has revealed that there is formation of tetrahydro-beta-carboline (THBC) derivatives which may originate from reaction with both the solvent and the ketone catalyst. The application of gas chromatography electron- and chemical-ionisation ion trap tandem mass spectrometry (GC-IT-MS-MS), in combination with nuclear magnetic resonance (NMR), led to the isolation and identification of 1,1-disubstituted-tetrahydro-beta-carbolines formed as major impurities in the tryptamine. Confirmation was by synthesis of the THBC derivatives from tryptamine using Pictet-Spengler cyclisation. Under EI-conditions, mass spectral characterisation of the THBCs suggests predominance of alkyl cleavage. These impurities will yield a useful profile for identification of the synthetic pathway and likely reagents employed, particularly a "fingerprint" of the ketone catalyst and an insight into the influence of solvents and catalysts on the formation of by-products.
School of Pharmacy and Chemistry, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF, UK.
Simon D
SD
Brandt
David
D
Mansell
Sally
S
Freeman
Ian A
IA
Fleet
John F
JF
Alder
D002243:Carbolines / Q000138:chemical synthesis*; D002264:Carboxylic Acids / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D007659:Ketones / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D021241:Spectrometry, Mass, Electrospray Ionization; D014363:Tryptamines / Q000737:chemistry*; D014364:Tryptophan / Q000737:chemistry*
D002243:Carbolines; D002264:Carboxylic Acids; D007659:Ketones; D014363:Tryptamines; C030820:tryptamine; D014364:Tryptophan