Reaktion #599920

Reaktionsgleichung

sodium ethoxide

3-Hydrazinopyridine.dihydrochloride

diethyl maleate

→

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

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigefrom 20° C. to 32° C
2. 2
   Temperaturthe reaction was heated at 60° C. for 3 hours
3. 3
   TemperaturThe reaction was cooled to 20° C.
4. 4
   Sonstigequenched with acetic acid
5. 5
   workup.ADDITIONThe reaction mixture was diluted with water (100 mL)
6. 6
   Extraktionextracted with ethyl acetate (3×100 mL)
7. 7
   EinengenThe combined organics were concentrated to dryness
8. 8
   Sonstigethe residue was purified by flash column chromatography

Vorschrift

A 4-neck round bottomed flask (250 mL) was charged with sodium ethoxide (21 wt % in ethanol, 56 mL, 192 mmol). 3-Hydrazinopyridine.dihydrochloride (10.0 g, 55.0 mmol) was added, causing an exotherm from 20° C. to 32° C. The reaction was allowed to cool to 20° C. and diethyl maleate (13.4 mL, 82.0 mmol) was added, and the reaction was heated at 60° C. for 3 hours. The reaction was cooled to 20° C. and quenched with acetic acid. The reaction mixture was diluted with water (100 mL) and extracted with ethyl acetate (3×100 mL). The combined organics were concentrated to dryness and the residue was purified by flash column chromatography using ethyl acetate as eluent to the title compound as a blue oil (6.60 g, 51%): 1H NMR (400 MHz, DMSO-d6) δ 10.40 (s, 1H), 8.40-8.26 (m, 1H), 8.19 (dd, J=4.4, 1.6 Hz, 1H), 7.47-7.21 (m, 2H), 4.77 (dd, J=9.8, 2.1 Hz, 1H), 4.22 (qd, J=7.1, 1.7 Hz, 2H), 3.05 (dd, J=17.0, 9.8 Hz, 1H), 1.99 (s, 1H), 1.25 (t, J=7.1 Hz, 3H); 13C NMR (101 MHz, DMSO-d6) δ 170.37, 146.60, 142.60, 137.28, 123.54, 121.94, 65.49, 61.32, 32.15, 20.72, 13.94; ESIMS m/z 236 ([M+H]+).

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