Diisopropylethylamine → 4-(2-Diisopropylaminoethylamino)benzenesulfonic acid 2-(8-tert-butoxycarbonylaminooctanoylamino)benzothiazol-6-yl ester

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Reaction Steps

175 mg of 8-tert-butoxycarbonylaminooctanoic acid, 256 mg of HBTU and 235 μl of DIEA are added to a solution of 4-(2-diisopropylaminoethylamino)-benzenesulfonic acid 2-aminobenzothiazol-6-yl ester (intermediate 34) (100 mg, 0.225 mmol) in 5 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 338 mg of crude oil. This oil is purified by elution in a 95/5 dichloromethane/methanol mixture at a flow rate of 10 ml/minute, on 10 g of silica, to give 153 mg of 4-(2-diisopropylaminoethylamino)benzenesulfonic acid 2-(8-tert-butoxycarbonylaminooctanoylamino)benzothiazol-6-yl ester.

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