Diphenyl Ether → 7-Bromoisoquinolin-1-ol

Participants

Reaction Steps

Preheated 2 separate oil baths to 240° C. A flask containing tributylamine (6.68 g, 36.1 mmol) and diphenyl ether (80 mL) was lowered into one oil bath (A), and a flask containing 3-(4-bromophenyl)acryloyl azide (7.91 g, 31.3 mmol) and diphenyl ether (80 mL) was lowered into the other oil bath (B) [vigorous gas evolution—internal temperature must quickly reach >200° C.]. After 10 minutes, the contents of flask B are poured into flask A, and the reaction left at 230-240° C. (internal temperature) for 30 minutes. Cooled reaction mixture to ˜100° C., poured into hexanes (2 L), stirred to cool to room temperature and filtered off the precipitate. Washed precipitate with methylene chloride/hexanes (ratio 1/50), dried under high vacuum to give a colorless powder (4.20 g, 18.8 mmol). 1H NMR (DMSO) δ 11.41 (s, 1H), 8.23 (s, 1H), 7.82 (dd, 1H), 7.62 (d, 1H), 7.20 (t, 1H), 6.54 (d, 1H). ESI MS (M+1)+: 224, 226 (Br).

Provenance & Evidence