Triethylamine → (R)-3-[3-(3-chloro-phenyl)-[1,2,4]oxadiazol-5-yl]-butyric acid methyl ester

Participants

Reaction Steps

To a solution of (R)-2-methylsuccinic acid 4-methyl ester (2.2 g, 15 mmol) and triethylamine (4.54 g, 45 mmol) in THF (30 ml), isobutylchloroformate (2.16 g, 15.8 mmol) was added dropwise at 0° C. After being stirred for 30 min, the 3-chloro-N-hydroxy-benzamidine (2.56 g, 15 mmol) was added. The reaction mixture was stirred at room temperature for another 30 min and then heated to 135° C. with DMF for 45 min. The reaction mixture was diluted with ethyl acetate and washed with water and brine. The organic layer was dried and concentrated to give 4.0 g (95%) of (R)-3-[3-(3-chloro-phenyl)-[1,2,4]oxadiazol-5-yl]-butyric acid methyl ester as pale-yellow oil. Step 2: (R)-3-[3-(3-Chloro-phenyl)-[1,2,4]oxadiazol-5-yl]-butyric acid hydrazide: (R)-3-[3-(3-Chloro-phenyl)-[1,2,4]oxadiazol-5-yl]-butyric acid hydrazide (430 mg, 77%) was obtained from (R)-3-[3-(3-chloro-phenyl)-[1,2,4]oxadiazol-5-yl]-butyric acid methyl ester (461.4 mg, 2.0 mmol) reacted with hydrazine hydrate (2 mL) in methanol (2 mL) at 65° C. for 1 h. 1H-NMR(CDCl3) d (ppm): 8.07 (s, 1H), 7.96 (d, 1H), 7.46 (m, 2H), 6.98 (w, 1H), 3.93 (w, 2H), 3.78 (m, 1H), 2.86 (dd, 1H), 2.55 (dd, 1H) and 1.59 (d, 3H).

Provenance & Evidence