Dimethyl Sulfate → HCID 19745794, compound

Participants

Reaction Steps

A solution of 6.1 g of 3-[6-fluoro-2-oxo-3-(2-propynyl)-5-benzothiazolinyl]-6-methyl-2,4(1H,3H)-pyrimidinedione (see Example 4) in 50 ml of dimethylformamide is added while stirring to a suspension of 0.8 g of a 55% sodium hydride dispersion in 25 ml of dimethylformamide. After the hydrogen evolution has finished the mixture is treated with 2.8 g of dimethyl sulphate and stirred for one hour. Thereafter, the reaction mixture is poured into 500 ml of water, the aqueous mixture is extracted three times with 100 ml of ethyl acetate each time and the organic phase is dried over anhydrous sodium sulphate. The solvent is subsequently distilled off under reduced pressure and the thus-obtained residue (7.2 g) is purified by chromatography on a column of 350 g of aluminium oxide (Brockmann I) using methylene chloride/n-hexane (3:1) as the eluent. The first fraction (1.5 g) is recrystallized from ethyl acetate, whereby there is obtained 1,6-dimethyl-3-[6 -fluoro-2-oxo-3-(1,2-propanedienyl)-5-benzothiazolinyl]-2,4(1H,3H)-pyrimidinedione, m.p.>250° C. By further elution of the column with methylene chloride/ethyl acetate (3:1) there is obtained the second fraction (4.7 g) which is recrystallized from ethyl acetate. In this manner there is obtained 1,6-dimethyl-3-[6-fluoro-2-oxo-3-(2-propynyl)-5-benzothiazolinyl]-2,4(1H,3H)-pyrimidinedione, m.p. 180°-181° C.

Provenance & Evidence