反应详情

H-Thr(Bzl)-OBzl hemioxalate (58 g, 168.4 mmol) was suspended in DMF (700 ml) and stirred with Boc-Val-OSu (48 g, 153.1 mmol) and Et3N (16 ml) at 0° C for 1 hr, 4° C for 72 hrs and 25° C for 24 hrs. It was necessary during this time to add at intervals additional Et3N in order to maintain the pH between 7 and 8. The reaction mixture was worked up as in Example 2 to yield an oil which crystallized from EtOAc with petroleum ether, yield 40.8 g (53.5%); mp 99°-100.5° C; [α]D25 -26.0° (c 1, MeOH). Anal. Calcd for C28H38N2O6 (498.62): C, 67.45; H, 7.68; N, 5.62. Found: C, 67.57; H, 7.55; N, 5.70.

1. temperatureto maintain the pH between 7 and 8
2. customto yield an oil which
3. customcrystallized from EtOAc with petroleum ether, yield 40.8 g (53.5%)