Investigation of the reaction of N-substituted indolylborates: Palladium catalyzed cross-coupling reactions and intramolecular alkyl migration reactions

The palladium catalyzed cross-coupling reaction of indolylborates with various N-protecting groups was investigated, where N-Methyl, N-methoxy, and N-tert-butoxycarbonyl groups were found to be useful. However, triethyl(1-methoxymethylindol-2-yl)borate could not be used for this reaction. It was also found that the alkyl migration reaction of trialkyl(1-methoxymethylindol-2-yl)borate produced 2-alkyl-1-methyl-indole accompanied by the unexpected reduction of 1-methoxymethyl group to 1-methyl group.