2-(p-hydroxybenzyl)indoles -: Side products formed upon cleavage of indole derivatives from carboxylated Wang polymer -: an NMR study

Treatment of carboxylated Wang polymer attached to a 2-unsubstituted indole derivative with a trifluoroacetic acid based mixture resulted in a side reaction: p-hydroxybenzylation at the 2-position of the indole ring. The structure of the resulting N-3-aminopropyl)-N-benzyl-4-[2-(4-hydroxybenzyl)-1H-indol-3-yl]-butyramide trifluoroacetate was ascertained by a full assignment of its H-1- and C-13-NMR spectra. The side reaction could be suppressed by the use of 1,2-ethanedithiol in high concentrations (16%).