A stainless steel hydrogenating vessel was successively charged with 1′-(diphenylmethyl)-5′-methylspiro[furo[2,3-f][1,3]benzodioxole-7,3′-indol]-2′(1′H)-one (0.90 g, 1.95 mmol), glacial acetic acid (50.0 mL) and palladium hydroxide (0.10 g, 1.35 mmol, 20 wt % on carbon). The vessel was flushed with nitrogen, sealed then heated to 60° C. and placed under 120 Psi of H2. After 4 days of stirring, the reaction mixture was diluted with ethyl acetate and passed through a bed of celite. The filtrate was washed with water (6×100 mL), dried over sodium sulfate and filtered. The filtrate was concentrated in vacuo to dryness. The residue was subjected to column chromatography eluting with ethyl acetate/hexane (40-50%) to afford the title compound (0.25 g, 43%): mp 269-271° C.; 1H NMR (300 MHz, DMSO-d6) δ 10.45 (s, 1H), 7.00 (d, 1H), 6.87 (s, 1H), 6.76 (d, 1H), 6.63 (s, 1H), 6.21 (s, 1H), 5.87 (d, 2H), 4.64 (ABq, 2H), 2.17 (s, 3H); MS (ES+) m/z 296.28 (M+1).
