Triethylamine → (E)-3-(2,3-dihydrobenzo[b][1,4]dioxin-5-yl)acryloyl azide

Participants

Reaction Steps

(E)-3-(2,3-dihydrobenzo[b][1,4]dioxin-5-yl)acrylic acid (5 g, 24.25 mmol), diphenylphosphoryl azide (4.96 mL, 23.04 mmol), and Et3N (6.76 mL, 48.5 mmol) were dissolved in benzene and stirred for 16 h. The solution was concentrated under vacuum and the residue was purified by silica gel chromatography using 20% EtOAc/Hexanes to give 4.5 g of (E)-3-(2,3-dihydrobenzo[b][1,4]dioxin-5-yl)acryloyl azide as a yellow solid, which was taken into PhCH2Ph (50 mL). The resulting solution was slowly heated to 80° C. for 1 h and then to reflux for 3 h. After cooling to rt, the solid was collected washing with benzene to give 3.5 g of the desired product 2,3-dihydro-[1,4]dioxino[2,3-f]isoquinolin-7-ol as a solid. 1H NMR (400 MHz, CD3OD) δ ppm 4.37 (m, 4H), 6.83 (d, J=7.09 Hz, 1H), 7.02 (d, J=8.80 Hz, 1H), 7.12 (d, J=7.34 Hz, 1H), 7.79 (d, J=8.80 Hz, 1H); MS: (M+H)+ 204.

Provenance & Evidence