Reaction Steps
A mixture of 1′-[(2-oxo-1,3-oxazolidin-5-yl)methyl]spiro[furo[2,3-f][1,3]benzodioxole-7,3′-indol]-2′(1′H)-one (0.32 g, 0.84 mmol), tetrabutylammonium bromide (0.05 g, 0.16 mmol), aqueous sodium hydroxide (0.10 g, 2.52 mmol) and dimethyl sulfate (0.21 g, 1.68 mmol) in anhydrous tetrahydrofuran (5 mL), was stirred at an ambient temperature for 1 h. The mixture was concentrated in vacuo to dryness. The residue was purified by column chromatography with ethyl acetate (30%) in hexanes to afford 1′-[(3-methyl-2-oxo-1,3-oxazolidin-5-yl)methyl]spiro[furo[2,3-f][1,3]benzodioxole-7,3′-indol]-2′(1′H)-one (0.13 g, 40%): mp 98-102° C.; 1H NMR (300 MHz, CDCl3) δ 7.39 (dd, J=7.7, 7.7 Hz, 1H), 7.18 (d, J=7.4 Hz, 1H), 7.07 (dd, J=7.5, 7.5 Hz, 1H), 6.88 (d, J=7.8 Hz, 1H), 6.49 (s, 1H), 6.05 (s, 1H), 5.84 (d, J=6.2 Hz, 2H), 4.74 (ABq, 2H), 3.93-3.88 (m, 2H), 3.82-3.74 (m, 1H), 2.92 (d, J=4.0 Hz, 3H), 2.55-2.40 (m, 1H), 2.36-2.26 (m, 1H), 2.20-2.07 (m, 1H), 1.95-1.85 (m, 1H); 13C NMR (75 MHz, CDCl3) δ 178.2, 178.1, 175.2, 175.1, 156.1, 156.0, 149.1, 142.5, 142.4, 142.2, 142.0, 132.1, 132.0, 129.2, 124.5, 124.4, 123.9, 123.8, 119.0, 118.9, 108.1, 102.8, 102.7, 101.6, 93.8, 93.7, 80.5, 80.4, 58.2, 58.1, 58.0, 57.9, 43.1, 43.0, 29.3, 29.2, 28.8, 28.7, 22.8, 22.7; MS (ES+) m/z 417.3 (M+1).
