Dimethylformamide dimethyl acetal → 7-bromo-5-nitro-1H-isochromen-1-one

Participants

Reaction Steps

A solution of methyl 5-bromo-2-methyl-3-nitrobenzoate (29.0 g, 106 mmol) and N,N-dimethylformamide dimethyl acetal (42.0 mL, 317 mmol) in N,N-dimethylformamide (200 mL) was stirred at 110° C. overnight. After cooling to room temperature, the reaction mixture was partitioned between ethyl acetate (300 mL) and water (300 mL). The organic phase was separated, washed with water (2×300 mL) and brine (1×3 00 mL), concentrated to dryness in the presence of silica gel, and purified by silica gel chromatography (eluting with a gradient of 0-80% ethyl acetate in heptane) to give 7-bromo-5-nitro-1H-isochromen-1-one (293a, 9.62 g, 32% yield) as a solid. 1H NMR (400 MHz, CDCl3-d) δ 8.76 (d, J=1.47 Hz, 1H), 8.60 (d, J=2.20 Hz, 1H), 7.46 (d, J=6.11 Hz, 1H), 7.34 (d, J=6.11 Hz, 1H). MS: 269 [M+1]

Provenance & Evidence