The fragmentation of tribenzylpyrogallol in a sodium environment by electrospray mass spectrometry results in what is presumed to be the rapid loss of two of the adjacent benzyl groups to form a stable ortho-quinone structure. In order to confirm the putative mechanism we required differentially deuterated tribenzylpyrogallol derivatives. Addition of benzyl bromide to pyrogallol in the presence of K2CO3 in DMF at 100�C gave ~60% isolated yield of a mixture of pyrogallol benzylated at the 1- and 2-positions (1:8) that could be separated by chromatography. In order to understand the preference for substitution at the 2-position and optimize the yield of the corresponding 2-benzylated product the base, solvent and reaction temperature were varied. Addition of d2- and d7-benzyl bromide afforded the desired deuterated tribenzylpyrogallol compounds. Characterization of these compounds via GC-MS and 1H and 13C NMR and possible reasons for the regiochemical preference in the substitution reaction will be presented.

Relative reactivity of the 1- and 2-positions of pyrogallol with benzyl bromide: Synthesis of differentially deuterated derivatives for mass spectrometric study

245th National Meeting (2013)

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