反应详情

A 100-mL round bottomed flask was charged with methyl 3-[3-(3-tert-butyloxycarbonylaminophenyl)-1,2,4-oxadiazol-5-yl]propionate (4.04 g, 11.6 mmol), lithium hydroxide (1.39 g, 58.2 mmol), methanol (15 mL), water (15 mL) and THF (15 mL). The resulting solution was then stirred for 2 h at room temperature. The solvents were then removed under reduced pressure and the residue dissolved into water (60 mL). The resulting solution was cooled to 0° C. and acidified to pH 5 by the addition of 2 N hydrochloric acid. The mixture was then extracted with ethyl acetate (4×50 mL) and the combined extracts dried over sodium sulfate. Filtration and concentration under reduced pressure afforded an 83% yield of 3-[3-(3-tert-butyloxycarbonylaminophenyl)-1,2,4-oxadiazol-5-yl]propionic acid as a white solid. m.p. 143-144° C.; 1H NMR (DMSO-d6) δ (ppm) 12.42 (bs, 1H), 9.60 (s, 1H), 8.24 (s, 1H), 7.57 (m, 2H), 7.42 (t, 1H,J=7.9 Hz), 3.26 (t, 2H,J=6.9 Hz), 2.84 (t, 2H,J=6.9 Hz), 1.49 (s, 9H); m/z=332 (M−H).

1. customThe solvents were then removed under reduced pressure
2. dissolutionthe residue dissolved into water (60 mL)
3. temperatureThe resulting solution was cooled to 0° C.
4. additionacidified to pH 5 by the addition of 2 N hydrochloric acid
5. extractionThe mixture was then extracted with ethyl acetate (4×50 mL)
6. dry with materialthe combined extracts dried over sodium sulfate
7. filtrationFiltration and concentration under reduced pressure