反应详情

温度

110 °C

An ethanolic solution of Ethyl 5-(4-nitrophenyl)oxazole-2-carboxylate (step D product, 3.4 g) and L-valine methyl ester hydrochloride (5.43 g) previously neutralized with Et3N (4.52 ml), was heated in a sealed tube at 110° C. for 2 days. EtOH was removed under reduced pressure and the crude material was chromatographed on silica gel in 1:9 EtOAc:Pet ether to get cream colored solid which was crystallized in EtOAc/pet ether to yield 700 mg (31%) of the title compound. 1HNMR (DMSO-d6, 300 MHz): δ 9.2 (d, 1H), 8.37 (d, 2H), 8.24 (s, 1H), 8.14 (d, 2H), 4.32 (m, 1H), 3.68 (s, 3H), 2.26 (m, 1H), 0.96 (t, 6H); MS (ES+): m/z 348 (M+1).

1. customEtOH was removed under reduced pressure
2. customthe crude material was chromatographed on silica gel in 1:9 EtOAc
3. customPet ether to get cream colored solid which
4. customwas crystallized in EtOAc/pet ether