Indole → 1-Methylindole

Beteiligte Stoffe

Reaktionsschritte

Potassium tert-butoxide was added to a solution of the indole product of Example 61 (354 mg, 1.12 mmol) and dimethyl oxalate (145 mg, 1.23 mmol) in DMF (3 mL) and heated to reflux for 1 h. The mixture was cooled to room temperature and quenched with water (5 mL). After extraction (2×) with CH2Cl2, the organic layer was dried over MgSO4/Na2SO4, filtered, and concentrated in vacuo. Purification by column chromatography (SiO2, 20 g, hexanes to 10% EtOAc/hexanes) provide the N-methyl indole product (163 mg, 44%) as a yellow powder: mp 120-124° C.; 1H NMR (500 MHz, CDCl3) δ 7.27-7.24 (m, 1H), 7.08 (d, J=8.5 Hz, 1H), 7.04 (d, J=3.1 Hz, 1H), 7.01 (d, J=10.4 Hz, 1H), 6.96 (d, J=8.2 Hz, 1H), 6.71 (d, J=8.5 Hz, 1H), 6.42 (d, J=3.1 Hz, 1H), 4.29 (t, J=5.8 Hz, 1H), 3.96 (d, J=15.2 Hz, 1H), 3.85 (d, J=15.2 Hz, 1H), 3.76 (s, 3H), 2.99 (dd, J=11.3, 5.2 Hz, 1H), 2.68 (dd, J=11.4, 6.5 Hz, 1H), 2.47 (s, 3H); IR (KBr) 3438, 2943, 2779, 1579, 1488, 1422, 1358, 1266, 1064 cm−1; ESI MS m/z=329 [C19H18ClFN2+H]+.

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