COC([C:5]1[CH2:10][C:9]([C:18]#[N:19])([C:11]2[CH:12]=[N:13][C:14]([F:17])=[CH:15][CH:16]=2)[CH2:8][CH2:7][C:6]=1[OH:20])=O.[Na+].[Cl-].O>CS(C)=O>[F:17][C:14]1[N:13]=[CH:12][C:11]([C:9]2([C:18]#[N:19])[CH2:8][CH2:7][C:6](=[O:20])[CH2:5][CH2:10]2)=[CH:16][CH:15]=1To a solution of 5-Cyano-5-(6-fluoro-pyridin-3-yl)-2-hydroxy-cyclohex-1-enecarboxylic acid methyl ester (32 g crude, 0.11 mmol) in DMSO (110 mL) was added NaCl (7.78 g, 0.133 mol) and water (6.5 mL). The reaction mixture was heated at 160° C. for 3 h. It was cooled to room temperature and poured into water (300 mL). The aqueous layer was extracted with EtOAc (3×200 mL). The combined organic layer was washed with brine (300 mL), dried over sodium sulphate, filtered and concentrated under reduced pressure. The residue was purified by flash column chromatography on silica gel (eluting with a gradient elution of between 10-25% EtOAc in petroleum ether) to give the title compound (12 g, 50% over two steps). 1H NMR (CDCl3 400 MHz): ppm 8.34 (d, J=2.4 Hz, 1H), 7.95-7.82 (m, 1H), 7.00-6.92 (m, 1H), 2.95-2.87 (m, 2H), 2.60-2.2. (m, 2H), 2.50-2.40 (m, 2H), 2.28-2.20 (m, 2H).
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