28 mg of acetic acid, 177.5 mg of HBTU and 163 μl of DIEA are added to a solution of 4-(2-diisopropylaminoethylamino)benzenesulfonic acid 2-amino-benzothiazol-6-yl ester (intermediate 34) (70 mg, 0.156 mmol) in 4 ml of dimethylformamide. The solution obtained is stirred for 20 hours at room temperature. After addition of 50 ml of water, the reaction mixture is extracted with 3 times 25 ml of ethyl acetate. The extracts are dried over magnesium sulfate, filtered and evaporated under reduced pressure to give 130 mg of crude oil. This oil is purified by LC/MS to give 15 mg of 4-(2-diisopropylamino-ethylamino)benzenesulfonic acid 2-acetylaminobenzothiazol-6-yl ester.
