Reaktion #6797

Reaktionsgleichung

indole

dimethyl oxalate

potassium tert-butoxide

→

N-methyl indole

Lösungsmittel

DMF

water

Reaktionsbedingungen

Aufarbeitung

1. 1
   TemperaturThe reaction mixture was warmed
2. 2
   Temperaturto reflux under nitrogen for 30 min
3. 3
   Extraktionextracted (3×) with methylene chloride
4. 4
   WaschenThe combined organic layers were washed with brine
5. 5
   Trocknendried over Na2SO4
6. 6
   Filtrationfiltered
7. 7
   Einengenconcentrated in vacuo
8. 8
   SonstigeThe residue was purified by chromatography (SiO2, EtOAc/hexanes, 1:1)

Vorschrift

To a solution of indole product from Example 38, Step F (182 mg, 0.694 mmol) and dimethyl oxalate (90 mg, 0.76 mmol) in DMF (5 mL), potassium tert-butoxide (86 mg, 0.76 mmol) was added in one portion at room temperature under nitrogen. The reaction mixture was warmed to reflux under nitrogen for 30 min and then was cooled to room temperature. The mixture was diluted with water (50 mL) and extracted (3×) with methylene chloride. The combined organic layers were washed with brine, dried over Na2SO4, filtered and concentrated in vacuo. The residue was purified by chromatography (SiO2, EtOAc/hexanes, 1:1) to afford the N-methyl indole product, Example 37, as a white solid (180 mg, 92%): mp 106-108° C.; 1H NMR (500 MHz, CDCl3) δ 7.19-7.28 (m, 5H), 7.05 (d, J=8.5 Hz, 1H), 7.03 (d, J=3.0 Hz, 1H), 6.73 (d, J=8.5 Hz, 1H), 6.41 (dd, J=3.0, <1 Hz, 1H), 4.37 (t, J=6.3 Hz, 1H), 4.00 (d, J=15.1 Hz, 1H), 3.85 (d, J=15.1 Hz, 1H), 3.75 (s, 3H), 3.08 (dd, J=11.4, 5.4 Hz, 1H), 2.66 (dd, J=11.4, 8.1 Hz, 1H), 2.50 (s, 3H); CI MS m/z=277 [C19H20N2+H]+; IR (KBr) 3050, 2939, 2783, 1487, 1451 cm−1; Anal. Calcd for C19H20N2-0.1 H2O: C, 82.04; H, 7.32; N, 10.07. Found: C, 82.06; H, 7.50; N, 9.85.

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