Methanesulfonic Acid → HCID 22735292, compound

Participants

Reaction Steps

3.35 g of 2-imino-8-trifluoromethoxy-4,5-dihydro-2H-thiazolo[3,4,5-de][1,4]benzothiazine are added to a solution, under argon and cooled to 5° C., of 5.3 g of 3-chloroperbenzoic acid (80% purity) in 100 ml of dichloromethane and the stirring is maintained for 16 hours at a temperature close to 20° C. 100 ml of a 1 M aqueous solution of sodium hydrogen carbonate are then added and the mixture is stirred for 1 hour at the same temperature. After separation of the two phases, the aqueous phase is extracted twice with 50 ml of dichloromethane and the combined organic extracts are dried over magnesium sulphate and concentrated to dryness under reduced pressure (2 kPa). The yellow oil obtained is chromatographed under nitrogen pressure (150 kPa) on 20 g of 20-45 μm silica gel contained in a column 2 cm in diameter, eluting with ethyl acetate. The product obtained (730 mg) is dissolved in 50 ml of absolute ethanol, and then 100 μl of methanesulphonic acid are added. After stirring for 1 hour 45 minutes, the precipitate is separated by filtration, washed with ethanol and then with ethyl ether and dried under reduced pressure (2 kPa) at 20° C. 750 mg of 2-imino-8-trifluoromethoxy-4,5-dihydro-2H-thiazolo[3,4,5-de]-[1,4]benzothiazine 6,6-dioxide methanesulphonate are thus obtained in the form of a white solid melting at a temperature greater than 260° C. [Analysis C11H11F3N2O6S3, % calculated C: 31.43, H: 2.64, F: 13.56, N: 6.66, S: 22.88, % found C: 31.39H: 2.29, F: 13.28, N: 6.59, S: 22.60].

Provenance & Evidence