C[O:2][C:3](=[O:25])[C:4]1[CH:9]=[C:8]([C:10]2[CH:11]=[N:12][C:13]([C:18]([F:21])([F:20])[F:19])=[CH:14][C:15]=2[C:16]#[N:17])[C:7]([Cl:22])=[CH:6][C:5]=1[O:23][CH3:24].[OH-].C[Sn+](C)C>ClCCCl>[Cl:22][C:7]1[C:8]([C:10]2[CH:11]=[N:12][C:13]([C:18]([F:19])([F:21])[F:20])=[CH:14][C:15]=2[C:16]#[N:17])=[CH:9][C:4]([C:3]([OH:25])=[O:2])=[C:5]([O:23][CH3:24])[CH:6]=1A mixture of 4-chloro-5-(4-cyano-6-trifluoromethyl-pyridin-3-yl)-2-methoxy-benzoic acid methyl ester (1.2 g, 3.2 mmol) and trimethyltin hydroxide (1.75 g, 9.7 mmol) in 1,2-dichloroethane (50 mL) was heated to 80° C. in a sealed tube for 4 hrs. Additional 5.0 eq. of trimethyltin hydroxide was added and the mixture was heated for total of 48 hrs. The mixture was then cooled to rt, quenched with HCl (2N, 40 mL) and diluted with 1,2-dichloroethane. The organic layer was separated, dried over Na2SO4, filtered and concentrated. The residue was purified via silica gel flash column chromatography eluting with dichloromethane:methanol (9:1) to afford 4-chloro-5-(4-cyano-6-trifluoromethyl-pyridin-3-yl)-2-methoxy-benzoic acid (723 mg). NMR (CDCl3), δ, 8.82 (1H, s), 7.94 (1H, s), 7.81 (1H, s), 7.20 (1H, s), 3.90 (3H, s).
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