1,5-Dibromopentane → 1'-(2-piperidin-1-ylethyl)spiro[furo[2,3-f][1,3]benzodioxole-7,3'-indol]-2'(1'H)-one

A mixture of 1′-(2-aminoethyl)spiro[furo[2,3-f][1,3]benzodioxole-7,3′-indol]-2′(1′H)-one (0.20 g, 0.62 mmol), 1,5-dibromopentane (0.08 mL, 0.62 mmol) and triethyl amine (0.17 mL, 1.23 mmol) in THF (10.0 mL) was refluxed for 15 hrs and concentrated in vacuo to dryness. The residue was subjected to flash chromatography eluting with 10% methanol in ethyl acetate to give 1′-(2-piperidin-1-ylethyl)spiro[furo[2,3-f][1,3]benzodioxole-7,3′-indol]-2′(1′H)-one, which was treated with 4.0 M HCl in dioxane to give the title compound (28%): mp>240° C.; 1H NMR (300 MHz, CD3OD) δ 7.40 (t, 1H), 7.27-7.11 (m, 3H), 6.51 (s, 1H), 6.17 (s, 1H), 5.86 (s, 2H), 4.91 (d, 1H), 4.71 (d, 1H), 4.40-4.13 (m, 2H), 3.95-3.84 (m, 1H), 3.66-3.37 (m, 3H), 3.14-2.96 (m, 2H), 2.06-1.45 (m, 6H); 13C NMR (75 MHz, CD3OD) δ 180.4, 157.5, 150.5, 143.8, 142.5, 133.9, 130.3, 125.3, 125.1, 120.6, 110.2, 103.9, 102.9, 94.2, 81.4, 59.7, 55.4, 54.9, 53.9, 36.4, 24.2, 22.6; MS (ES+) m/z 393 (M+1).