Isopropanol → (RS)-3-(2-Dimethylaminopropyl)2-imino-6-trifluoromethoxybenzothiazoline

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Reaction Steps

2-Amino-6-trifluoromethoxybenzothiazole (9.4 g) and 2-chloro-1-dimethylaminopropane hydrochloride (7.0 g) are heated for 1 hour to 130.C. 2-Propanol (20 cc) is added and heating is continued for 24 hours to boiling. After cooling of the mixture to a temperature in the region of 20.C, the precipitate is filtered off and then treated with IN sodium hydroxide (80 cc) in distilled water (100 cc). The residue obtained by extraction with dichloromethane, drying over magnesium sulphate and concentration to dryness under reduced pressure (20 mm Hg; 2.7 kPa) is purified by chromatography on a silica column with a mixture of ethyl acetate and methanol (80:20 by volume) as eluent. (RS)-3-(2-Dimethylaminopropyl)2-imino-6-trifluoromethoxybenzothiazoline (3.3 g) is obtained in the form of a yellow oil, which is converted to a dihydrochloride subliming at about 190° C.

Provenance & Evidence