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

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a light yellow solution of (E)-ethyl 3-(dimethylamino)acrylate (1.72 g, 12.0 mmol) in toluene (20 mL) was added triethylamine (1.21 g, 1.67 mL, 12.0 mmol) at room temperature. To this, a solution of 3-chloropicolinoyl chloride (34) (1.76 g, 10 mmol) in toluene (5 mL, heated to dissolve) was added. Then, the resulting dark brown solution was heated to 83° C. and stirred for 12 h at this temperature. During this period, it turned to a dark brown solution. Then, the heating was stopped and the dark brown mixture was filtered off and the solids were washed with ethyl acetate. The brown ethyl acetate solution was washed with water which was diluted with 1.0N HCl. The acidic aqueous layer was extracted one more time with ethyl acetate and the combined organic layer was washed with brine solution and dried over anhydrous MgSO4. Filtration and concentration gave only 1.6 g of crude brown mixture. Then, the acidic aqueous layer was extracted with dichloromethane (2×100 mL) and then the aqueous layer was neutralized with a saturated sodium bicarbonate solution and then extracted one more time with dichloromethane. The combined dichloromethane extracts were washed with brine solution and dried over anhydrous MgSO4. Filtration and concentration gave another 1.2 g of dark drown oil which was combined with the first brown residue and the mixture was purified using an ISCO (120 g) column, eluting with ethyl acetate in hexanes (0 to 100%) and then 10% methanol in dichloromethane. The pure fractions were combined and the solvent was removed under vacuum to obtain (Z)-ethyl 3-(dimethylamino)-2-(3-chloropicolinoyl)acrylate (35) (1.16 g, 41% yield) as a dark brown oil.

Herkunft & Nachweise