[NH2:1][C:2]1[NH:3][CH:4]([CH:20]([CH3:22])[CH3:21])[C:5]([C:15]([O:17][CH2:18][CH3:19])=[O:16])=[C:6]([C:8]2[CH:13]=[CH:12][C:11]([F:14])=[CH:10][CH:9]=2)[N:7]=1>C1(C)C=CC=CC=1.[O-2].[O-2].[Mn+4]>[NH2:1][C:2]1[N:7]=[C:6]([C:8]2[CH:9]=[CH:10][C:11]([F:14])=[CH:12][CH:13]=2)[C:5]([C:15]([O:17][CH2:18][CH3:19])=[O:16])=[C:4]([CH:20]([CH3:21])[CH3:22])[N:3]=1Ethyl 2-amino-4-(4-fluorophenyl)-6-isopropyl-1,6-dihydropyrimidine-5-carboxylate (22.6 g) was dissolved in toluene (150 ml) and heated until a solution was obtained. Manganese dioxide (18.8 g) was added as a slurry in toluene (150 ml) and the mixture refluxed under azeotropic conditions for 6 hours until conversion was complete. A small amount of water was collected in the Dean and Stark trap. The slurry was filtered and the solvents removed by evaporation under reduced pressure to give ethyl 2-amino-4-(4-fluorophenyl)-6-isopropyl-pyrimidine-5-carboxylate as a crystalline solid in 96% yield.
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