Synthesis
To a stirred suspension of orotic acid (20.00 g, 128.140 mmol) in POCI3(75 ml) was added DMF (catalytic amount, -0.5 ml) at ambient temperature, and the resulting reaction mixture was refluxed for 3 h. Excess of POC was removed by vacuum distillation after 3h of reflux. The obtained slurry was poured slowly into a 5 per cent mixture of methanol in chloroform (200 ml) at 0°C and stirred for 30 min. The organic layer obtained was washed with a saturated solution of NaHCC>3 (3 x 200 ml). The combined organic phase was dried over Na2S04, filtered and concentrated under reduced pressure, yielding Methyl 2,4-dichloropyrimidine-6-carboxylate (19.00 g, 91 .800 mmol).
