Chloroform → 7-hydroxy-2-(4-[4-(4-fluorobenzoyl)-piperidin-1-yl]-butyl}-2H-1,4-benzothiazine-3(4H)-one

Participants

Reaction Steps

675 mg (=0.0015 m) of 7-methoxy-2-(4-[4-(4-fluorobenzoyl)-piperidin-1-yl]-butyl)-2H-1,4benzothiazine-3(4H)-one (see Example 18) prepared analogously to Example 4 were placed in 5 ml of dichloromethane with exclusion of moisture. After cooling to -5° C. a solution of 1.10 g of boron tribromide in 1 ml of methylene chloride was added dropwise with stirring. Stirring was then continued for a further 30 minutes at room temperature. The reaction mixture was worked up by adding it with stirring to a mixture of ice and aqueous sodium hydrogen carbonate solution. 200 ml of chloroform were then added. The resulting organic solution was washed with water, dried over sodium sulfate, filtered, and concentrated under reduced pressure. The title compound was obtained from the remaining residue by fractional column chromatography. The fractions containing the title compound were concentrated and treated with ether. 55 mg of 7-hydroxy-2-{4-[4-(4-fluorobenzoyl)-piperazin-1-yl]-butyl} -2H-1,4-benzothiazine-3(4H)-one were obtained.

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