Sulfuric Acid → 4,5-Dihydrobenzo[b]furo[3,4-d]oxepine-1,3-dione

Participants

Reaction Steps

To potassium tert-butoxide (1.35 g, 12 mmol) in tetrahydrofuran (30 mL) was added diethyl oxalate (2.2 g, 15 mmol) and ethyl 4-phenoxybutanoate (2.08 g, 10 mmol) in tetrahydrofuran (30 mL) at 0° C. dropwise. The mixture was allowed to stir overnight, concentrated, quenched with 1 N HCl(aq), extracted with ethyl acetate, and concentrated. A fraction of this material (308 mg, 1 mmol) was added to concentrated H2SO4 at 0° C. The mixture was stirred for 1.5 hours and was poured onto ice chips. The precipitate was collected to afford the title compound. 1H NMR (300 MHz, DMSO-d6) δ ppm 8.44 (dd, J=1.5, 8.1 Hz, 1H), 7.48 (t, J=8.1 Hz, 1H), 7.25 (t, J=7.8 Hz, 1H), 7.14 (d, J=8.4 Hz, 1H), 4.28 (t, J=5.1 Hz, 2H), and 3.02 (t, J=5.1 Hz, 2H).

Provenance & Evidence