Reaction Steps
A stirred solution of spiro[furo[2,3-f][1,3]benzodioxole-7,3′-indol]-2′(1′H)-one (1.0 g, 3.6 mmol), N-methylpiperazine (3.6 g, 36.0 mmol) and formaldehyde (37% wt solution in water, 2.9 mL, 36.0 mmol) in methanol was refluxed for 20 h. The solution was concentrated in vacuo to dryness and recrystallized from ether in hexanes to afford the free base form of 1′-[(4-methylpiperazin-1-yl)methyl]spiro[furo[2,3-f][1,3]benzodioxole-7,3′-indol]-2′(1′H)-one as a pale orange solid (1.15 g, 81%). To a solution of 1′-[(4-methylpiperazin-1-yl)methyl]spiro[furo[2,3-f][1,3]benzodioxole-7,3′-indol]-2′(1′H)-one (0.50 g, 12.7 mmol) in methanol (5 mL) was added hydrochloric acid saturated methanol (10 mL). The precipitate that formed was filtered and dried in vacuo to afford 1′-[(4-methylpiperazin-1-yl)methyl]spiro[furo[2,3-f][1,3]benzodioxole-7,3′-indol]-2′(1′H)-one hydrogen chloride (0.65 g, quantitative) as a colorless solid: mp>175° C. (dec.); 1H NMR (300 MHz, DMSO-d6) δ11.59 (br s, 1H), 9.43 (br s, 1H), 7.41 (d, J=7.9 Hz, 1H), 7.31 (dd, J=7.6, 7.6 Hz, 1H), 7.15 (d, J=6.6 Hz, 1H), 7.06 (dd, J=7.4, 7.4 Hz, 1H), 6.66 (s, 1H), 6.47 (s, 1H), 5.89 (s, 2H), 4.86-4.73 (m, 3H), 4.61 (d, J=9.5 Hz, 1H), 3.54-3.28 (m, 4H), 3.27-2.94 (m, 4H), 2.71 (s, 3H); MS (ES+) m/z 394.0 (M+1). Anal. Calcd. for C20H23N3O4.2HCl.0.5H2O: C, 55.59; H, 5.51; N, 8.84. Found: C, 55.47; H, 5.43; N, 8.78.
