Reaction Steps
To a stirred solution of 6-[2-(dimethylamino)ethoxy]spiro[1-benzofuran-3,3′-indol]-2′(1′H)-one (0.21 g, 0.64 mmol) in 2-butanone (10 mL) was added (R)-(tetrahydrofuran-2-yl)methyl 4-methylbenzenesulfonate (0.20 g, 0.76 mmol) followed by cesium carbonate (0.63 g, 1.90 mmol) at 0° C. The mixture was stirred at ambient temperature for 16 h. The reaction mixture was filtered and the filtrate was concentrated in vacuo. The residue was subjected to column chromatography (ethyl acetate/methanol/ammonium hydroxide, 10/1/0.2) to give 6-[2-(dimethylamino)ethoxy]-1′-[(2R)-tetrahydrofuran-2-ylmethyl]spiro[1-benzofuran-3,3′-indol]-2′(1′H)-one (0.20 g, 76%): 1H NMR (300 MHz, CDCl3) δ 7.31-7.24 (m, 1H), 7.14-6.96 (m, 3H), 6.57 (d, J=8.3 Hz, 1H), 6.52 (d, J=2.2 Hz, 1H), 6.36 (dd, J=8.3, 2.2 Hz, 1H), 4.91 (d, J=9.0 Hz, 1H), 4.66 (d, J=9.0 Hz, 1H), 4.31-4.19 (m, 1H), 4.00 (t, J=5.8 Hz, 2H), 3.94-3.63 (m, 4H), 2.68 (t, J=5.8 Hz, 2H), 2.97 (s, 6H), 2.09-1.63 (m, 4H); 13C NMR (75 MHz, CDCl3) δ 178.1, 177.9, 162.0, 160.7, 142.9, 142.8, 132.5, 132.4, 128.7, 128.6, 123.7, 123.6, 123.5, 123.4, 123.2, 121.1, 121.0, 109.6, 109.4, 108.1, 97.2, 80.6, 80.5, 68.24, 68.2, 66.3, 58.2, 57.5, 45.9, 44.6, 44.5, 29.2, 28.9, 25.7, 25.5; MS (ES+) m/z 409.3 (M+1).
