Anzemet → methanesulfonic acid;(10-oxo-8-azatricyclo[5.3.1.03,8]undecan-5-yl) 1H-indole-3-carboxylate;hydrate

Methanesulphonic acid (0.34 mL, 5.24 mmol) is added to a solution of 1H-Indole-3-carboxylic acid 10-oxo-8-aza-tricyclo[5.3.1.03,8]undec-5-yl ester (1.6 gr, 4.93 mmol) in acetone (20 mL) and under nitrogen, maintaining the reaction temperature around 25° C. Following stirring at 0° C. for 3 h, and at room temperature for one night, the solid that forms is filtered and washed with acetone. The product formed is recrystallised from isopropanol-water (95:5 by weight), to obtain 1H-Indole-3-carboxylic acid 10-oxo-8-aza-tricyclo[5.3.1.03,8]undec-5-yl ester methanesulphonate monohydrate (1.71 gr, 79%) in the form of a white solid.