Acetic Acid → 1-{[5-(1-methyl-1H-indol-2-yl)-pyridin-3-ylamino]-methyl}-cyclobutanecarboxylic acid ethyl ester

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Reaction Steps

To a solution of 2-(5-amino-pyridin-3-yl)-1-methyl-1H-indole (Example 100, 0.400 g, 1.756 mmol) and 1-formyl-cyclobutanecarboxylic acid ethyl ester (0.457 g, 2.633 mmol) in dichloromethane (13 mL) is added acetic acid (0.102 g, 1.756 mmol) and the mixture is refluxed. After 2 h, the mixture is cooled with an ice-water bath and sodium tri-acetoxyborohydride (1.175 g, 5.267 mmol) is added. After 13 h, the mixture is heated to reflux for 1.5 h, cooled to room temperature, diluted with dichloromethane, washed with 1M aqueous NaOH, water and brine. The combined aqueous phase is extracted once with dichloromethane and the combined organic phase is dried over MgSO4, filtered and concentrated in vacuo. The residue is purified by silica gel flash chromatography (heptane-ethyl acetate, 1:1) to give 1-{[5-(1-methyl-1H-indol-2-yl)-pyridin-3-ylamino]-methyl}-cyclobutanecarboxylic acid ethyl ester as an oil. 1H NMR (400 MHz, CDCl3) δ ppm 1.28 (t, J=7.1 Hz, 3H), 1.99-2.12 (m, 4H), 2.49-2.59 (m, 2H), 3.53 (d, J=5.8 Hz, 2H), 3.78 (s, 3H), 4.12-4.18 (m, 1H), 4.20 (q, J=7.1 Hz, 2H), 6.61 (d, J=0.8 Hz, 1H), 7.04 (dd, J=2.8, 1.9 Hz, 1H), 7.15-7.19 (m, 1H), 7.26-7.30 (m, 1H), 7.39 (dd, J=8.2, 0.8 Hz, 1H), 7.65 (d, J=7.7 Hz, 1H), 8.09 (d, J=2.8 Hz, 1H), 8.12 (d, J=1.9 Hz, 1H).

Provenance & Evidence