Reaction Steps
A solution of 1′-[(1-ethylpiperidin-4-yl)methyl]-5,6-dihydrospiro[benzo[1,2-b:5,4-b′]difuran-3,3′-indol]-2′(1H)-one (0.17 g, 0.41 mmol) and hydrogen chloride (4.0 M in 1,4-dioxane, 0.40 mL, 1.6 mmol) in methanol (1.0 mL) was stirred at ambient temperature for 35 min. The solvent was removed under reduced pressure, the residue was suspended in ethyl acetate/hexanes and the precipitate was collected by filtration and washed with hexanes. The precipitate was dried to afford 1′-[(1-ethylpiperidin-4-yl)methyl]-5,6-dihydrospiro[benzo[1,2-b:5,4-b′]difuran-3,3′-indol]-2′(1′H)-one hydrochloride (0.18 g, 100%) as an off-white powder: mp 135° C. (dec.) (hexanes); 1H NMR (300 MHz, CD3OD) δ7.36 (dd, J=6.9, 6.6 Hz, 1H), 7.20-7.07 (m, 3H), 6.49 (s, 1H), 6.32 (s, 1H), 4.83 (d, J=9.2 Hz, 1H), 4.67 (d, J=9.2 Hz, 1H), 4.50 (t, J=8.3 Hz, 2H), 3.84-3.68 (m, 2H), 3.65-3.54 (m, 2H), 3.21-3.10 (m, 2H), 3.02-2.87 (m, 4H), 2.31-2.16 (m, 1H), 2.08-1.95 (m, 2H), 1.76-1.58 (m, 2H), 1.35 (t, J=6.2 Hz, 3H); 13C NMR (75 MHz, CD3OD) δ180.4, 163.2, 162.9, 143.8, 133.9, 130.1, 124.9, 124.8, 121.5 (2C), 120.1, 110.5, 93.7, 81.8, 73.5, 59.2, 53.4, 53.0, 45.9, 34.0, 29.9, 28.7 (2C), 9.7; MS (ES+) m/z 405.2 (M+1).
