C(=O)([O-])[O-].[Cs+].[Cs+].[Cl:7][C:8]1[C:9](F)=[N:10][CH:11]=[C:12]([F:14])[CH:13]=1.[OH:16][C:17]1[CH:22]=[CH:21][C:20]([C:23]2[N:28]([CH3:29])[C:27](=[O:30])[N:26]([CH2:31][O:32][CH2:33][CH2:34][Si:35]([CH3:38])([CH3:37])[CH3:36])[C:25](=[O:39])[C:24]=2[CH3:40])=[C:19]([CH3:41])[CH:18]=1.O>CS(C)=O>[Cl:7][C:8]1[C:9]([O:16][C:17]2[CH:22]=[CH:21][C:20]([C:23]3[N:28]([CH3:29])[C:27](=[O:30])[N:26]([CH2:31][O:32][CH2:33][CH2:34][Si:35]([CH3:38])([CH3:37])[CH3:36])[C:25](=[O:39])[C:24]=3[CH3:40])=[C:19]([CH3:41])[CH:18]=2)=[N:10][CH:11]=[C:12]([F:14])[CH:13]=1Cesium carbonate (476 mg, 1.46 mmol) was added to a mixture of 3-chloro-2,5-difluoropyridine (97%, 150 mg, 0.97 mmol) and C5 (366 mg, 0.972 mmol) in dimethyl sulfoxide (5 mL), and the reaction mixture was stirred at 80° C. for 6 hours. Water was added, and the mixture was extracted three times with ethyl acetate; the combined organic layers were washed with saturated aqueous sodium chloride solution, dried over sodium sulfate, filtered, and concentrated in vacuo. Silica gel chromatography (Gradient: 10% to 40% ethyl acetate in heptane) provided the product as a sticky solid. Yield: 414 mg, 0.818 mmol, 84%. 1H NMR (400 MHz, CDCl3) δ 7.96 (d, J=2.7 Hz, 1H), 7.64 (dd, J=7.1, 2.7 Hz, 1H), 7.09-7.15 (m, 3H), 5.51 (AB quartet, JAB=9.3 Hz, ΔνAB=3.4 Hz, 2H), 3.74-3.80 (m, 2H), 3.07 (s, 3H), 2.19 (s, 3H), 1.69 (s, 3H), 1.00-1.06 (m, 2H), 0.03 (s, 9H).
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