0.833 g (6.82 mMol) of DMAP, 1.38 g (13.6 mMol) of triethylamine and 13.9 g (136 mMol) of acetic anhydride are added, under nitrogen, to a stirred solution of 6.0 g (13.6 mMol) of 2-[1-(4-chlorobenzyl)-1H-indol-3-yl]-2-oxo-N-quinolin-6-ylacetamide in 60 ml of DMF. The reaction mixture is stirred at room temperature for 10 minutes and, after that, poured into 200 ml of ethyl acetate. After 300 ml of water have been added, the mixture is shaken in a separating funnel after which the two phase separate. Precipitation begins after 20 minutes. The pale yellow crystals are filtered off and dried in vacuo at 60° C.
