[F:1][C:2]1[N:6]([CH3:7])[N:5]=[C:4]([CH3:8])[C:3]=1[C:9]([NH:11][C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][C:13]=1[C:18]([OH:24])([CH3:23])[CH2:19][CH:20]([CH3:22])[CH3:21])=O.C1(C)C=CC(S(O)(=O)=O)=CC=1.O>C1(C)C=CC=CC=1>[F:1][C:2]1[N:6]([CH3:7])[N:5]=[C:4]([CH3:8])[C:3]=1[C:9]1[O:24][C:18]([CH2:19][CH:20]([CH3:21])[CH3:22])([CH3:23])[C:13]2[CH:14]=[CH:15][CH:16]=[CH:17][C:12]=2[N:11]=1The above product from step 2 is boiled in 150 ml of toluene with 0.2 g of p-toluenesulphonic acid on a water separator for 2 h. The mixture is washed with aqueous sodium bicarbonate solution and the organic phase is concentrated under reduced pressure. By stirring with heptane, it is possible to precipitate and remove by filtration the N-(2-acetylphenyl)-5-fluoro-1,3-dimethyl-1H-pyrazole-4-carboxamide still present from the previous step. Chromatography gives 7.2 g (purity 85.1%; 63% of theory) of 2-(5-fluoro-1,3-dimethyl-1H-pyrazol-4-yl)-4-isobutyl-4-methyl-4H-3,1-benzoxazine.
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