To a solution of 5-fluoro-3-(hydroxyimino-methyl)-1-naphthalen-1-ylmethyl-1H-indole-2-carboxylic acid ethyl ester (1.17 g) in AcOH (75 ml) was added at 22° C. sodium acetate (4.9 g) followed by portion wise addition of zinc dust (0.78 g) and stirring was continued at 22° C. for 3 h. The mixture was evaporated and the residue partitioned between ice-cold aqueous 2 N NaOH and t-butylmethyl ether. The aqueous layer was extracted several times; the combined organic layers were dried and evaporated. The residue was dissolved in EtOH saturated with HCl (10 ml), the solution was stirred at 22° C. for 16 h and evaporated again. The residue was suspended in t-butylmethyl ether and the suspension was filtered to give 3-aminomethyl-5-fluoro-1-naphthalen-1-ylmethyl-1H-indole-2-carboxylic acid ethyl ester; salt with hydrogen chloride as a yellow solid. MS: 377.3 ([M+H]+).
