反应详情

To 3-(4-(benzyloxy)phenyl)isoxazole-5-carboxylic acid (300 mg) in THF (10 ml), N-methyl morpholine (0.111 ml) was added and reaction mixture was stirred for 10 minutes at RT. Reaction mixture was cooled to −20° C., isobutyl chloroformate (0.132 ml) was added and stirred for 15-20 minutes at −20 to −30° C. L-valine methyl ester hydrochloride (238 mg) neutralized with Et3N (0.198 ml) in THF (5 ml) and added to the above reaction mixture and stirred at −20 to −30° C. for 5 minutes. Then the reaction mixture was gradually allowed to warm to RT over a period of 1 hour. Solvent was evaporated to obtain pale brown solid, which was purified by column chromatography (silica gel, EtOAc—Chloroform) to obtain off white solid, which was crystallized using EtOAc—petroleum ether to obtain the title compound as white solid. Yield: 232 mg (55%); MS (ES+): m/z 409 (M+1); 1H NMR (DMSO-d6; 300 MHz): δ 9.19 (d, 1H), 7.87 (d, 2H), 7.68 (s, 1H), 7.32-7.49 (m, 5H), 7.19 (d, 2H), 5.19 (s, 2H), 4.31 (m, 1H), 3.67 (s, 3H), 2.22 (m, 1H), 0.96 (d, 6H).

1. customreaction mixture
2. customReaction mixture
3. temperaturewas cooled to −20° C.
4. stirringstirred for 15-20 minutes at −20 to −30° C
5. additionadded to the above reaction mixture
6. stirringstirred at −20 to −30° C. for 5 minutes
7. temperatureto warm to RT over a period of 1 hour
8. customSolvent was evaporated
9. customto obtain pale brown solid, which
10. customwas purified by column chromatography (silica gel, EtOAc—Chloroform)
11. customto obtain off white solid, which
12. customwas crystallized