41214-27-1

98232-51-0

General procedure for the synthesis of 8-methoxy-3,4-dihydrobenzo[b]oxepin-5(2H)-one from 3-methoxyphenoxybutyric acid: a chlorobenzene solution of polyphosphoric acid (PPA) was slowly added to compound Int-19d (22 g, 0.1 mol) at 80 °C and the reaction mixture was kept stirred continuously at 80 °C for about 15 hours. After completion of the reaction, the solvent was removed and the residue was dissolved in ethyl acetate and washed sequentially with 1N aqueous sodium hydroxide and saturated saline. The organic layer was dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to afford the target compound Int-19e (14 g, 73% yield). The product was characterized by 1H NMR (CDCl3) with chemical shifts δ: 7.74 (d, J = 8Hz, 1H), 6.63 (d, J = 8Hz, 1H), 6.53 (s, 1H), 4.21 (t, J = 12Hz, 2H), 3.80 (s, 3H), 2.84 (t, J = 16Hz, 2H), 2.18-2.15 (m, 2H ).