Dimethylformamide → 6-Chloro-5-nitro-1H-isochromen-1-one

Participants

Reaction Conditions

Reaction Steps

A pressure tube was-charged with methyl 4-chloro-2-methyl-3-nitrobenzoate (13 g, 57 mmol) in N,N-dimethylformamide (10 mL, 200 mmol) was added 1,1-dimethoxy-N,N-dimethylmethanamine (26.5 mL, 200 mmol) and the reaction heated to 120° C. for 20 h. The solvents were removed and the resultant brown residue was redissolved in ethyl acetate (600 mL, 6000 mmol) and 130-270 mesh 60A silica gel (500 g, 6000 mmol) was added and the reaction stirred with a mechanical stirrer for 8 h. The silica gel was filtered off, washed with ethyl acetate (400 mL) and the organics were removed under vacuum and the residue purified by flash chromatography (330 g silica gel, 2-50% ethyl acetate/hexane) to obtain the two isomers in 14% yields each in almost 98% purity. MS m/z=226.2 (M+H). 1H NMR (400 MHz; DMSO) δ 8.35 (d, J=8.63 Hz, 1H), 7.95 (d, J=8.63 Hz, 1H), 7.76 (d, J=5.91 Hz, 1H), 6.61 (d, J=6.04 Hz, 1H).

Provenance & Evidence