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Analytical Differentiation of 1-Alkyl-3-acylindoles and 1-Acyl-3-alkylindoles: Isomeric Synthetic Cannabinoids

NCJ Number
Analytical Chemistry Volume: 86 Issue: 8 Dated: April 2016 Pages: 3801-3808
Date Published
April 2016
8 pages
This study determined that the 1-alkyl-3-acylindoles and the inverse regioisomeric 1-acyl-3-alkylindoles of synthetic cannabinoids can be prepared directly from a common set of precursor materials using similar synthetic strategies.

The EI mass spectra for these isomers show a number of unique ions which allow for the differentiation of the 1-alkyl-3-acylindole compounds from the inverse regioisomeric 1-acyl-3-alkylindoles. The base peak at m/z 214 in the 1-n-pentyl-3-benzoylindole represents the M-77 cation fragment resulting from the loss of the phenyl group, and this ion is not observed in the inverse isomer. The 1-benzoyl-3-n-pentylindole inverse regioisomer shows a base peak at m/z 105 for the benzoyl cation. Thus, these two base peaks are the result of fragmentation initiated at the carbonyl-oxygen for both isomers. The 1-pentyl-3-benzoylindole is characterized by the strong intensity carbonyl band at 1703 cm-1, and the amide carbonyl appears as a strong band of equal intensity at 1681 cm-1 in the 1-benzoyl-3-pentyl regioisomer. (Publisher abstract modified)

Date Published: April 1, 2016