Sodium hydride → 6-{[5-(trifluoromethyl)furan-2-yl]methyl}-2,3-dihydro-6H-[1,4]dioxino[2,3-f]indole-7,8-dione

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Reaction Steps

To a stirred solution of 2,3-dihydro-6H-[1,4]dioxino[2,3-f]indole-7,8-dione (Lackey and Sternbach, Synthesis 1993:993-997) (3.08 g, 15.0 mmol) in dry N,N-dimethylformamide (150 mL) was added sodium hydride (0.9 g, 60% in mineral oil, 22.5 mmol) at ambient temperature. The deep purple mixture was stirred for 20 min followed by the addition of 2-(bromomethyl)-5-(trifluoromethyl)furan (3.80 g, 16.5 mmol) in one portion. The dark solution was stirred at ambient temperature for 1 h and concentrated in vacuo to dryness. The residue was mixed with water (150 mL) and stirred. The fine orange precipitation was filtered off and dried to afford 6-{[5-(trifluoromethyl)furan-2-yl]methyl}-2,3-dihydro-6H-[1,4]dioxino[2,3-f]indole-7,8-dione (4.13 g, 78%): 1H NMR (300 MHz, CDCl3) δ7.18 (s, 1H), 6.76-6.73 (m, 1H), 6.48 (s, 1H), 6.45-6.40 (m, 1H), 4.85 (s, 2H), 4.42-4.32 (m, 2H), 4.28-4.20 (m, 2H).

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