Ammonia → (2'-oxo-5,6-dihydrospiro[benzo[1,2-b:5,4-b']difuran-3,3-indol]-1'(2'H)-yl)acetamide

Participants

Reaction Steps

To a stirred solution of (2′-oxo-5,6-dihydrospiro[benzo[1,2-b:5,4-b′]difuran-3,3′-indol]-1′(2′H)-yl)acetic acid (0.25 g, 0.74 mmol), triethylamine (0.5 mL), ammonia in dioxane (0.5M, 4.5 mL, 2.3 mmol) in acetonitrile (10 mL) was added 2-(7-aza-1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (0.33 g, 0.9 mmol). The solution was stirred at ambient temperature for 18 h then concentrated in vacuo to dryness. The residue was dissolved in ethyl acetate (50 mL) and washed with 2 M sodium carbonate (2×25 mL) and 1 M hydrochloric acid (2×25 mL). The ethyl acetate layer was dried over anhydrous magnesium sulfate, filtered and concentrated in vacuo to dryness. Recrystallization from diethyl ether (25 mL) in a Branson ultrasonic bench top water bath afforded 2-(2′-oxo-5,6-dihydrospiro[benzo[1,2-b:5,4-b′]difuran-3,3′-indol]-1′(2′H)-yl)acetamide (0.06 g, 23%) as a colorless solid: 1H NMR (300 MHz, DMSO-d6) δ7.66 (s, 1H), 7.29-7.21 (m, 2H), 7.10 (d, J=6.5 Hz, 1H), 7.03-6.90 (m, 2H), 6.55 (s, 1H), 6.36 (s, 1H), 4.72 (ABq, 2H), 4.53-4.38 (m, 1H), 4.29 (ABq, 2H), 2.92 (t, J=8.6 Hz, 2H); MS (ES+) m/z 337.1 (M+1), 359.1 (M+23).

Provenance & Evidence