Acetic Acid → 6-Chloro-4-o-tolyl-nicotinic acid

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13.0 g (82.5 mMol) 6-Chloro-nicotinic acid in 65 ml THF were cooled to 0° C. and 206.3 ml (206.3 mMol) o-tolylmagnesium chloride solution (1M in THF) were added over 45 minutes. The solution obtained was further stirred 3 hours at 0° C. and overnight at room temperature. It was cooled to −60° C. and 103.8 ml (1.8 Mol) acetic acid were added, followed by 35 ml THF and 44.24 g (165 mMol) manganese(III) acetate dihydrate. After 30 minutes at −60° C. and one hour at room temperature, the reaction mixture was filtered and THF removed under reduced pressure. The residue was partitioned between water and dichloromethane and extracted. The crude product was filtered on silica gel (eluent: ethyl acetate/toluene/formic acid 20:75:5) then partitioned between 200 ml aqueous half-saturated sodium carbonate solution and 100 ml dichloromethane. The organic phase was washed with 50 ml aqueous half-saturated sodium carbonate solution, The combined aqueous phases were acidified with 25 ml aqueous HCl 25% and extracted with dichloromethane. The organic extracts were dried (Na2SO4) and concentrated under reduced pressure to yield 10.4 g (51%) of 6-chloro-4-o-tolyl-nicotinic acid as a yellow foam. MS (ISN): 246 (M−H, 100), 202 (M-CO2H, 85), 166 (36).

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