반응 #9070

반응 방정식

(2-hydroxyphenyl)-terephthalamic acid methyl ester

water

K2CO3

→

methyl 4-(benzoxazol-2-yl)-benzoate

수율 91.1%

용매

—

polyphosphoric acid

ethyl acetate

반응 조건

후처리

1. 1
   온도to reflux for 3 h
2. 2
   workup.ADDITIONintroduced until pH 7–9
3. 3
   추출the organic extract
4. 4
   건조dried (MgSO4)
5. 5
   여과filtered
6. 6
   농축concentrated

실험 절차

A solution of (2-hydroxyphenyl)-terephthalamic acid methyl ester (0.35 g, 1.3 mmol) in polyphosphoric acid (˜5 mL) was heated to reflux for 3 h. The solution was cooled to 0° C., water added (100 mL) and solid K2CO3 introduced until pH 7–9 was attained. The residue was diluted with ethyl acetate (2×100 mL) and the organic extract dried (MgSO4), filtered and concentrated to give cyclized methyl 4-(benzoxazol-2-yl)-benzoate (0.15 g, 45%) as a beige powder. 1H NMR (CDCl3) δ 3.98 (s, 3H), 7.40 (m, 2H), 7.61 (m, 1H), 7.81 (m, 1H), 8.20 (d, 2H, J=7.8 Hz), 8.34 (d, 2H, J=7.8 Hz).

출처