Unusual reactivity of 2-amino-1H-indole-3-carboxylate esters

We report the outcome of the attempted synthesis of amino-1H-indole-3-carboxylic acid from the corresponding ethyl and tert-butyl esters.Subjection of the tert-butyl ester to acidic conditions led to quantitative conversion to indolin-2-imine hydrochloride and the ethyl ester to basic conditions led to a ringopened product, showing that the carboxylic acid is not easily-accessible via the corresponding esters.During the synthesis of the esters, the novel compound 2-(2-(trifluoromethyl)-1H-benzo[d]imidazol-1-yl)phenol was isolated and was shown to be chiral due to atropisomerism.