Reaktionsschritte
To a stirred solution of 5,6-dihydro-2H-spiro[benzofuro[6,5-b]furan-3,3′-indolin]-2′-one (1.0 g, 3.6 mmol) in dry N,N-dimethylformamide (18 mL) was added sodium hydride (60% in mineral oil, 0.17 g, 4.3 mmol) at ambient temperature. The mixture was stirred at ambient temperature for 1 h, cooled in an ice/water bath, and 1-(benzyloxy)-3-(bromomethyl)benzene (1.4 g, 5.0 mmol) in dry N,N-dimethylformamide (2 mL) was added dropwise. The mixture was stirred at ambient temperature for 16 h. Water (200 mL) and ethyl acetate (200 mL) were added to the mixture. The organic solution was separated and the aqueous layer was extracted with ethyl acetate (2×100 mL). The combined organic solution was washed with brine (150 mL), dried over anhydrous magnesium sulfate, filtered, and concentrated in vacuo. The residue was purified by column chromatography (hexanes/ethyl acetate 3:1) to afford 1′-[3-(benzyloxy)benzyl]-5,6-dihydrospiro[benzo[1,2-b:5,4-b′]difuran-3,3′-indol]-2′(1′H)-one (1.4 g, 82%) as a colorless solid: mp 66-68° C.; 1H NMR (300 MHz, CDCl3) δ 7.43-7.14 (m, 8H), 7.06-6.99 (m, 1H), 6.97-6.87 (m, 3H), 6.81-6.75 (m, 1H), 6.48 (s, 1H), 6.43 (s, 1H), 5.10-5.00 (m, 3H), 4.85-4.75 (m, 1H), 4.84 (ABq, 2H), 4.56-4.47 (m, 2H), 2.98-2.88 (m, 2H); 13C NMR (75 MHz, CDCl3) δ 177.9, 161.8, 161.3, 159.2, 142.1, 137.4, 136.6, 132.7, 129.9, 128.7, 128.6, 128.0, 127.5, 123.8, 123.4, 120.2, 119.9 (2C), 118.8, 114.0, 113.9, 109.3, 93.2, 80.5, 72.3, 70.0, 57.7, 44.0, 29.0; MS (ES+) m/z 476.1 (M+1).
