[NH2:1][C:2]1[C:19]([F:20])=[C:18]([F:21])[C:5]2[N:6]([C:10]3[CH:15]=[CH:14][C:13]([I:16])=[CH:12][C:11]=3[F:17])[C:7](=[O:9])[NH:8][C:4]=2[C:3]=1[OH:22].[C:23]1(C)C=CC(S(O)(=O)=O)=CC=1.C(OCC)(=O)C>C(OCC)(OCC)OCC.CCCCCC>[F:20][C:19]1[C:2]2[N:1]=[CH:23][O:22][C:3]=2[C:4]2[NH:8][C:7](=[O:9])[N:6]([C:10]3[CH:15]=[CH:14][C:13]([I:16])=[CH:12][C:11]=3[F:17])[C:5]=2[C:18]=1[F:21]A mixture of 5-amino-6,7-difluoro-1-(2-fluoro-4-iodo-phenyl)-4-hydroxy-1,3-dihydro-benzoimidazol-2-one (I-13a: 550 mg, 1.3 mmol) in triethyl orthoformate (5 mL) and p-toluene sulfonic acid (20 mg, 0.13 mmol) were taken in a flask and the flask was heated to reflux at 120° C. for 30 minutes. The reaction was monitored by TLC (70% ethyl acetate in hexane). The reaction mixture was concentrated under reduced pressure and the concentrate was triturated with diethyl ether and filtered. The residue was washed with diethyl ether and dried under reduced pressure to afford 300 mg of the product (54.5% yield). H1NMR (DMSO-d6, 300 MHz): δ 12.50 (s, 1H), 8.87 (s, 1H), 7.97 (dd, 1H), 7.78 (d, 1H), 7.50 (t, 1H). LCMS: 92.2%, m/z=431.9 (M+1).
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