Following the procedure as described in EXAMPLE 2 and making non-critical variations using 3-(7-hydroxy-4-methyl-3,4-dihydro-2H-1,4-benzoxazin-6-yl)-1-{[5-(trifluoromethyl)furan-2-yl]methyl}-1,3-dihydro-2H-indol-2-one trifluoroacetate salt to replace 1-(diphenylmethyl)-3-(2-hydroxy-4-methoxy-5-methylphenyl)-1,3-dihydro-2H-indol-2-one, 1-methyl-1′-{[5-(trifluoromethyl)furan-2-yl]methyl}-2,3-dihydro-1H-spiro[furo[3,2-g][1,4]benzoxazine-8,3′-indol]-2′(1′H)-one was obtained. To a suspension of 1-methyl-1′-{[5-(trifluoromethyl)furan-2-yl]methyl}-2,3-dihydro-1H-spiro[furo[3,2-g][1,4]benzoxazine-8,3′-indol]-2′(1′H)-one (0.59 g, 1.3 mmol) in methanol (8.5 mL) was added 4 M hydrochloric acid in 1,4-dioxane (1.5 mL, 6.0 mmol) and the resulting solution was stirred at ambient temperature for 35 min. The solvent was removed and the residue was dried under reduced pressure. The residue was then precipitated by addition of hexanes, sonicated and the solvent was removed under reduced pressure. This process was repeated several times, until the solid formed a fine suspension in hexanes. The material was then collected by filtration and air-dried to afford 1-methyl-1′-{[5-(trifluoromethyl)furan-2-yl]methyl}-2,3-dihydro-1H-spiro[furo[3,2-g][1,4]benzoxazine-8,3′-indol]-2′(1′H)-one hydrochloride (0.60 g, 94%) as a pale gray powder: mp 105° C. (dec.) (hexanes); 1H NMR (300 MHz, DMSO-d6) δ7.33 (ddd, J=7.8, 7.5, 0.9 Hz, 1H), 7.22-7.17 (m, 3H), 7.07 (dd, J=7.5, 7.5 Hz, 1H), 6.74 (d, J=3.3 Hz, 1H), 6.48 (s, 1H), 6.25-6.19 (m, 1H), 5.10 (d, J=16.2 Hz, 1H), 5.02 (d, J=16.2 Hz, 1H), 4.76 (d, J=9.3 Hz, 1H), 4.65 (d, J=9.3 Hz, 1H), 4.33-4.22 (m, 2H), 3.27-3.18 (m, 2H), 2.68 (s, 3H); 13C NMR (75 MHz, DMSO-d6) δ176.4, 157.2, 153.2, 147.9, 141.9, 139.6 (q, J=42.0 Hz), 131.3, 129.0, 123.9, 123.4, 121.5, 119.0 (q, J=267 Hz), 114.2 (q, J=2.8 Hz), 112.4, 109.9, 109.3, 98.8, 79.9, 62.7, 57.1, 48.8, 48.6, 41.5, 36.6; MS (ES+) m/z 457.1 (M+1); Anal. Calcd. for C24H19FN2O4.HCl: C, 58.49; H, 4.09; N, 5.68. Found: C, 58.85; H, 3.74; N, 5.37.
