Reaction #4375

Reaction equation

6-chlorothieno[3,2-d]pyrimidin-4(3H)-one

bromine

→

title compound

Yield 44.0%

7-Bromo-6-chlorothieno[3,2-d]pyrimidin-4(3H)-one

Yield 44.0%

Solvents

acetic acid

Conditions

Workup

1. 1
   TemperatureHeating
2. 2
   Otherprecipitated
3. 3
   Filtrationthe mixture was filtered
4. 4
   Washwashed with acetic acid, water and acetone

Procedure

A solution of 1.12 g (0.006 mole) of 6-chlorothieno[3,2-d]pyrimidin-4(3H)-one and 15 ml of acetic acid at 80° C. was treated with 2.88 g (0.92 ml, 0.018 mole) of bromine. Heating was continued for 2.5 hours during which time solids precipitated. After cooling to room temperature, the mixture was filtered and washed with acetic acid, water and acetone. There was obtained 0.70 g (44%) of the title compound: m.p. above 280° C.; mass spectrum 264 (molecular ion and parent peak with expected isotope pattern), 239 (-27), 186 (some starting material) among others; 1H-nmr (trifluoroacetic acid) delta 7.5 ppm (starting material, s 0.1H), 9.3 (s, 1.0H). The nmr spectrum indicates that the reaction product is about 90% of the desired product; the remainder is starting material. This material is sufficiently pure for use in further reactions.

Source