Reaction Steps
A mixture of 5,6-dihydrospiro[benzo[1,2-b:5,4-b′]difuran-3,3′-indol]-2′(1′H)-one (0.28 g, 1.0 mmol), 2-(bromomethyl)tetrahydro-2H-pyran (0.36 g, 2.0 mmol) and cesium carbonate (1.00 g, 3.0 mmol) was stirred in butanone at 80° C. for 3 h. Upon cooling to ambient temperature, the reaction mixture was filtered, and the filtrate was evaporated under reduced pressure. The residue was subjected to column chromatography with ethyl acetate-hexanes (1:5-1:1) to afford 1′-(tetrahydro-2H-pyran-2-ylmethyl)-5,6-dihydrospiro[benzo[1,2-b:5,4-b′]difuran-3,3′-indol]-2′(1′H)-one (0.31 g, 82%) as a colorless solid: 1H NMR (300 MHz, CDCl3) δ7.38-6.94 (m, 4H), 6.47 (d, J=2.9 Hz, 1H), 6.38 (s, 1H), 4.79 (ABq, 2H), 4.50 (t, J=8.6 Hz, 2H), 4.01-3.61 (m, 4H), 3.37 (t, J=11.1 Hz, 1H), 2.97 (t, J=8.4 Hz, 2H), 1.97-1.27 (m, 6H); 13C NMR (75 MHz, CDCl3) δ178.1 (2C), 161.7 (2C), 161.3, 161.2, 143.2, 143.1, 132.8, 132.7, 128.6 (2C), 123.5, 123.1, 123.1, 120.6, 120.5, 119.8 (2C), 119.0, 118.9, 109.7, 93.2, 93.1, 80.6, 75.7, 75.5, 72.3, 68.4 (2C), 57.7, 57.6, 45.8, 45.7, 29.6, 29.5, 29.1, 25.8, 23.0; MS (ES+) m/z 378.3 (M+1).
