Diisopropylethylamine → 3-{6-[4-(2-Diisopropylaminoethylamino)benzenesulfonyloxy]benzothiazol-2-yl-carbamoyl}azetidine-1-carboxylic acid tert-butyl ester

Participants

Reaction Steps

68 mg of azetidine-1,3-dicarboxylic acid mono-tert-butyl ester, 256 mg of HBTU and 235 μl of DIEA are added to a solution of 4-(2-diisopropylamino-ethylamino)benzenesulfonic acid 2-aminobenzothiazol-6-yl ester (inter-mediate 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 medium 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 700 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 20 g of silica, to give 39 mg of 3-{6-[4-(2-diisopropylaminoethylamino)-benzenesulfonyloxy]benzothiazol-2-ylcarbamoyl}azetidine-1-carboxylic acid tert-butyl ester.

Provenance & Evidence