Chlorosuccinimide → 6-Chloro-2-propoxy-3-propylthieno[2,3-d]pyrimidin-4(3H)-one

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Reaction Conditions

Reaction Steps

In a sulfonation flask, 10.1 g (0.04 mol) of 2-propoxy-3-propyl-3H-thieno[2.3-d]pyrimidin-4-one are added with stirring to 50 ml of absolute pyridine. The internal temperature is then raised to 70-75° C. and 9.0 g (0.07 mol) of N-chlorosuccinimid (NCS) are added over about 10 minutes in smallish portions. After stirring for 2 hours at 70-75° C., the pyridine is removed in a water-jet vacuum and the residue taken up in ethyl acetate. After washing twice with cold dilute aqueous hydrochloric acid, drying over sodium sulfate and removing the solvent in a water-jet vacuum, the crude product is obtained. The purification of the crude product is accomplished by column chromatography over silica gel (eluant: ethyl acetate/hexane=1:5), giving 7.8 g 6-chloro-2-propoxy-3-propyl-3H-thieno[2.3-d]pyrimidin-4-one in the form of a white powder having a melting point of 62-65° C.

Provenance & Evidence