Reaction Steps
To a solution of 6-[(diphenylmethylene)amino]-1′-pentylspiro[1-benzofuran-3,3′-indol]-2′(1′H)-one in anhydrous tetrahydrofuran (4.00 mL) was added aqueous 10% hydrochloric acid (2.00 mL). The reaction mixture was stirred for 15 min, diluted with aqueous sodium bicarbonate (5.00 mL) and extracted with ethyl acetate (3×25.0 mL). The combined organic solution was dried over sodium sulfate and filtered. The filtrate was concentrated in vacuo to dryness. The residue was subjected to column chromatography (ethyl acetate/hexane, 1/1) to give the title compound (0.02 g, 24% yield) as a yellow oil: 1H NMR (300 MHz, CDCl3) δ 7.26 (td, 1H), 7.12 (d, 1H), 6.99 (dd, 1H), 6.89 (d, 1H), 6.43 (d, 1H), 6.23 (d, 1H), 6.08 (dd, 1H), 4.86 (d, 1H), 4.60 (d, 1H), 3.86-3.60 (m, 2H), 1.77-1.65 (m, 2H), 1.41-1.30 (m, 4H), 0.89 (t, 3H); 13C NMR (75 MHz, CDCl3) δ 177.8, 171.2, 162.1, 148.7, 142.5, 133.1, 128.6, 127.8, 123.9, 123.7, 123.0, 118.5, 108.5, 108.4, 97.2, 80.2, 77.6, 77.4, 77.2, 76.8, 64.0, 60.4, 57.6, 40.3, 29.7, 29.0, 27.1, 22.6, 22.4, 22.1, 19.1, 14.2, 14.0, 13.7; MS (ES+) m/z 323.5 (M+1).
