Reaction Steps
4′-Furan-3-ylspiro[furo[2,3-f][1,3]benzodioxole-7,3′-indol]-2′(1′H)-one (0.25 g) was resolved on a semi-preparative chiral column (CHIRALPAK-IA, Chiral Technologies, Inc.) and eluted with 5% acetonitrile in tert-butylmethylether at 30 mL/min. Each run consisted of 50 mg of the racemate dissolved first in dimethylsulfoxide (0.15 mL) and diluted with acetonitrile (0.85 mL) and tert-butylmethylether (1.00 mL). The product isolated was dissolved in dimethylsulfoxide (2.0 mL), precipitated with water (50.0 mL), filtered and air dried to afford (7R)-4′-furan-3-ylspiro[furo[2,3-f][1,3]benzodioxole-7,3′-indol]-2′(1′H)-one (0.10 g, 75%) as a colorless solid. This enantiomer was the second to elute: mp 229-231° C. (water); 1H NMR (300 MHz, DMSO-d6) δ 10.64 (s, 1H), 7.57 (dd, J=1.6, 1.6 Hz, 1H), 7.27 (dd, J=7.8, 7.8 Hz, 1H), 7.03 (s, 1H), 6.90 (dd, J=7.1, 7.1 Hz, 2H), 6.55 (s, 1H), 6.32 (s, 1H), 6.06 (d, J=0.8 Hz, 1H), 5.92 (d, J=4.8 Hz, 2H), 4.60 (d, J=9.4 Hz, 1H), 4.44 (d, J=9.4 Hz, 1H); 13C NMR (75 MHz, DMSO-d6) δ 179.2, 156.1, 148.8, 143.8, 143.3, 142.0, 140.5, 130.5, 129.6, 128.9, 124.3, 123.2, 121.4, 111.3, 109.7, 103.3, 101.9, 93.7, 77.6, 58.6; MS (ES+) m/z 347.9 (M+1).
