Reaction Steps
To a mixture of 2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-2′(1′H)-one (0.23 g, 0.79 mmol), 6-methyl-2-pyridinemethanol (0.13 g, 1.07 mmol) and triphenylphosphine (0.30 g, 1.14 mmol) in benzene (10 mL) under nitrogen was slowly added a solution of diethyl azodicarboxylate (0.22 g, 1.27 mmol) in tetrahydrofuran (6 mL). The resulting mixture was stirred at ambient temperature for 16.5 h. The solvents were removed under reduced pressure, and the residue was taken up into 2 M sodium carbonate (50 mL) and extracted with dichloromethane (3×30 mL). The combined organic solution was washed with brine (50 mL), dried with sodium sulfate, filtered and concentrated under reduced pressure. Purification by flash column chromatography with hexanes/ethyl acetate (2:1) gave 1′-[(6-methylpyridin-2-yl)methyl]-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-2′(1′H)-one (0.13 g, 41%) as a colorless solid: mp 183-185° C. (hexanes/diethyl ether); 1H NMR (300 MHz, CDCl3) δ7.56 (dd, J=7.8, 7.5 Hz, 1H), 7.23-7.16 (m, 2H), 7.10-7.00 (m, 3H), 6.90 (d, J=7.8 Hz, 1H), 6.51 (s, 1H), 6.32 (s, 1H), 5.23 (d, J=15.9 Hz, 1H), 4.958 (d, J=9.0 Hz, 1H), 4.956 (d, J=15.9 Hz, 1H), 4.68 (d, J=9.0 Hz, 1H), 4.23-4.18 (m, 2H), 4.15-4.11 (m, 2H), 2.59 (s, 3H); 13C NMR (75 MHz, CDCl3) δ177.8, 158.2, 155.4, 154.7, 144.8, 142.2, 138.4, 138.2, 132.3, 129.0, 124.0, 123.7, 122.9, 121.2, 118.8, 111.8, 109.8, 99.6, 80.3, 64.7, 64.1, 58.3, 45.7, 24.1; MS (ES+) m/z 401.0 (M+1).
