[BH4-].[Na+].[Cl:3][C:4]1[C:5]([C:14](=[O:22])[C:15]2[CH:20]=[CH:19][C:18]([Cl:21])=[CH:17][CH:16]=2)=[N:6][CH:7]=[C:8]([C:10]([F:13])([F:12])[F:11])[CH:9]=1.Cl>C(O)C>[Cl:3][C:4]1[C:5]([CH:14]([C:15]2[CH:20]=[CH:19][C:18]([Cl:21])=[CH:17][CH:16]=2)[OH:22])=[N:6][CH:7]=[C:8]([C:10]([F:13])([F:12])[F:11])[CH:9]=1With ice-cooling, 0.36 g of sodium borohydride were added a little at a time to a solution of 6.0 g of 3-chloro-2-(4-chlorobenzoyl)-5-trifluoromethylpyridine in 10 ml of anhydrous ethanol. The reaction mixture was stirred at 23° C. for 20 hours, after which 50 ml of 10% strength hydrochloric acid were carefully added dropwise. The ethanol was evaporated and the product was subsequently extracted with tert-butyl methyl ether (three times 30 ml). The combined organic phases were dried over sodium sulfate and then concentrated. The crude product was purified by silica gel chromatography (eluent: cyclohexane/tert-butyl methyl ether=9:1). Yield: 3.6 g (60%) of a colorless oil; 1H NMR (270 MHz; in CDCl3): δ[ppm]=5.02 (d,1H), 6.02 (d,1H), 7.33-7.41 (m,4H), 7.91 (s,1H), 8.81 (s,1H).
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