Reaction Steps
To a solution of 3-[(2′-oxo-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-1′(2′H)-yl)methyl]benzoic acid (0.50 g, 1.16 mmol) in anhydrous chloroform (25 mL) was added oxalyl chloride (0.25 mL, 2.9 mmol) and anhydrous N,N-dimethylformamide (1 drop). The reaction mixture was stirred at ambient temperature for 2 h and concentrated in vacuo. The residue was dissolved in anhydrous dichloromethane (10 mL) and the resultant solution was added dropwise to a cooled (0° C.) solution of dimethylamine hydrochloride (1.56 g, 18.9 mmol) and triethylamine (5.27 mL, 37.8 mmol) in anhydrous dichloromethane (10 mL). The reaction mixture was stirred at 0° C. for 45 min and at ambient temperature for 3 h, filtered and concentrated in vacuo. The residue was recrystallized from hexanes to afford N,N-dimethyl-3-[(2′-oxo-2,3-dihydrospiro[furo[2,3-g][1,4]-benzodioxine-8,3′-indol]-1′(2′H)-yl)methyl]benzamide (0.04 g, 8%) as a light brown solid: mp: 90-96° C. (hexanes); 1H NMR (300 MHz, CDCl3) δ 7.37-7.34 (m, 4H), 7.21-7.14 (m, 2H), 7.04-7.00 (m, 1H), 6.77-6.75 (m, 1H), 6.49 (s, 1H), 6.19 (s, 1H), 5.08-5.03 (m, 1H), 4.93-4.82 (m, 2H), 4.67-4.64 (m, 1H), 4.20-4.09 (m, 4H), 3.08 (s, 3H), 2.90 (s, 3H); 13C NMR (75 MHz, CDCl3) δ 177.6, 171.1, 155.3, 144.7, 141.9, 138.3, 137.0, 136.0, 132.1, 129.1, 128.9, 128.3, 126.6, 126.0, 124.0, 123.6, 120.9, 111.5, 109.2, 99.5, 80.2, 64.5, 63.9, 58.0, 43.9, 39.6, 35.3; MS (ES+) m/z 456.8 (M+1).
