Triethylamine → (Z)-Ethyl 3-(dimethylamino)-2-(3-fluoropicolinoyl)acrylate

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To a light yellow solution of (E)-ethyl 3-(dimethylamino)acrylate (5.15 g, 36.0 mmol) in toluene (50 mL) was added triethylamine (3.64 g, 5.02 mL, 36.0 mmol) at room temperature. To this, a dark brown suspension of 3-fluoropicolinoyl chloride (30) (4.79 g, 30 mmol) in toluene (50 mL, heated to dissolve, but not dissolved completely) was added in one portion using a funnel. Then, the resulting dark brown solution was heated to 83° C. and stirred for 1.5 h at this temperature. During this period, it turned to a dark brown solution and TLC analysis indicated the presence of a new spot. Then, the heating was stopped and the dark brown mixture was diluted with ethyl acetate (200 mL) and the brown solution was washed with water, brine solution, and dried over anhydrous MgSO4. Filtration and concentration gave the crude brown mixture which was purified using ISCO (120 g) column chromatography, eluting with ethyl acetate in hexanes (0 to 100%) and then 5 to 20% methanol in dichloromethane. The desired fractions were combined and the solvent was removed under vacuum to obtain the (Z)-ethyl 3-(dimethylamino)-2-(3-fluoropicolinoyl)acrylate (31) (1.33 g, 15% yield) as a dark brown paste.

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