O[C:2]1[N:7]=[CH:6][N:5]=[C:4]([C:8]([O:10][CH2:11][CH3:12])=[O:9])[C:3]=1[CH3:13].O=P(Cl)(Cl)[Cl:16]>>[Cl:16][C:2]1[N:7]=[CH:6][N:5]=[C:4]([C:8]([O:10][CH2:11][CH3:12])=[O:9])[C:3]=1[CH3:13]A solution of ethyl 6-hydroxy-5-methylpyrimidine-4-carboxylate 40 (100 g, 549 mmol) in POCl3 (1000 ml) was heated to reflux for 5 h at 100° C. in sealed tube. After cooling to RT, the excess POCl3 was removed under reduced pressure, then quenched with ice water and extracted with EtOAc. The combined organic phase is washed with water, brine and concentrated under reduced pressure to afford ethyl 6-chloro-5-methylpyrimidine-4-carboxylate 41 as a black liquid. Yield: 80 (72%). This material was used as such for next step without purification.
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