Characterization of 4-bromo-2,5-dimethoxyphenethyl tosylate: A Synthetic Intermediate of 2C-B Identified in a Seized Heart-Shaped Tablet

A pink heart-shaped tablet seized by law enforcement authorities was found to contain a compound structurally related to 4-bromo-2,5-dimethoxyphenethylamine (2C-B), a controlled psychoactive phenethylamine of the 2C-series. Preliminary GC–MS analysis indicated the presence of a brominated phenethyl derivative, but its fragmentation pattern did not match any compound listed in available toxicological spectral libraries. A comprehensive analytical investigation combining GC–MS (EI), HPLC–HRMS/MS, and one- and two-dimensional NMR spectroscopy was therefore carried out. High-field and low- field NMR analysis revealed two structural fragments corresponding to a dimethoxy- substituted bromophenethyl moiety and a p-toluenesulfonyl group. HRMS analysis revealed isotopic ion pairs consistent with ammonium and sodium adducts of a mono-brominated species, allowing assignment of the neutral molecular formula C₁₇H₁₉BrO₅ S (MW 414/416 u), corresponding to 4-bromo-2,5-dimethoxyphenethyl tosylate. As the proposed compound had not been previously reported in major chemical databases (SciFinder and Reaxys), targeted synthesis was undertaken. The synthesized material was fully superimposable with the seized sample by NMR and MS, providing definitive structural confirmation. Comparative GC–MS analysis with an authentic 2C-B standard revealed shared fragment ions arising from the common brominated phenethyl core, together with diagnostic signals specific to the tosylated derivative, thus enabling reliable differentiation in routine forensic workflows. These findings highlight the importance of integrated spectroscopic and mass-spectrometric strategies for the identification of previously unreported synthetic intermediates related to controlled substances within the evolving New Psychoactive Substances (NPS) landscape.