Реакция #85398

Уравнение реакции

Sodium carbonate

ethyl 5-oxo-2-(pyridin-3-yl)pyrazolidine-3-carboxylate

acetonitrile

Phosphoryl trichloride

→

title compound

Выход 79.7%

Ethyl 3-chloro-1-(pyridin-3-yl)-4,5-dihydro-1H-pyrazole-5-carboxylate

Выход 79.7%

Растворители

water

Условия реакции

Обработка

1. 1
   ТемператураThe reaction was cooled to 20° C.
2. 2
   Экстракцияthe mixture was extracted with ethyl acetate (3×100 mL)
3. 3
   КонцентрированиеThe organic layers were concentrated to dryness
4. 4
   Другоеthe residue was purified by flash column chromatography

Методика

A 3-neck round bottomed flask (100 mL) was charged with ethyl 5-oxo-2-(pyridin-3-yl)pyrazolidine-3-carboxylate (8.50 g, 36.1 mmol) and acetonitrile (40 mL). Phosphoryl trichloride (4.05 mL, 43.4 mmol) was charged and the reaction was heated at 60° C. for 2 hours. The reaction was cooled to 20° C. and water (100 mL) was added. Sodium carbonate was added to adjust pH to 8 and the mixture was extracted with ethyl acetate (3×100 mL). The organic layers were concentrated to dryness and the residue was purified by flash column chromatography using 30-80% ethyl acetate/hexanes as eluent to provide the title compound as a yellow oil (7.30 g, 79%): 1H NMR (400 MHz, CDCl3) δ 8.30 (dd, J=2.9, 0.8 Hz, 1H), 8.17 (dd, J=4.7, 1.4 Hz, 1H), 7.38 (ddd, J=8.4, 2.8, 1.4 Hz, 1H), 7.18 (ddd, J=8.4, 4.7, 0.7 Hz, 1H), 4.79 (dd, J=12.4, 6.9 Hz, 1H), 4.24 (qd, J=7.1, 1.1 Hz, 2H), 3.55 (dd, J=17.7, 12.4 Hz, 1H), 3.33 (dd, J=17.8, 6.9 Hz, 1H), 1.25 (t, J=7.1 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ 169.65, 141.90, 141.33, 141.09, 135.13, 123.53, 120.37, 62.89, 62.35, 42.45, 14.03; ESIMS m/z 254 ([M+H]+).

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