Reaktion #54611
ord-101eefa9a8d24c31a3ac4402adca4457
Reaktionsgleichung
Reagenzien
Reaktionsbedingungen
Aufarbeitung
- 1Sonstigea white solid powder was obtained (44.0 g, mp 179°-184°)
- 2Temperaturcooled to 0°
- 3workup.ADDITIONwas added in several portions
- 4Temperaturmaintaining
- 5Sonstigethe reaction slightly basic
- 6SonstigeThe insoluble matter was removed by filtration
- 7Sonstigethe filtrate evaporated to dryness
- 8workup.DISSOLUTIONThe oily residue was dissolved in CH2Cl2
- 9Waschenwashed with 5% HOAc, H2O
- 10Trocknendried (Na2SO4)
- 11Sonstigeevaporated to a smaller volume (0.5 liter) when
- 12workup.ADDITIONtreated with petroleum ether
- 13SonstigeThe product crystallized slowly during overnight
- 14SonstigeIt was recrystallized from THF and i-PrOH
- 15Sonstigeto yield
Vorschrift
Boc-Asp(OBzl)-Thr(Bzl)-Ser(Bzl)-Ser(Bzl)-Glu(OBzl)-OH (50.0 g, 46 mmol) was deprotected with HCl (4.15 N) in THF and worked up as usual to give 45.4 g of white solid. It was dissolved in THF (1.5 liters) and treated with ether (7 liters). On standing at 0° overnight a white solid powder was obtained (44.0 g, mp 179°-184°). Part of this material, HCl.H-Asp(OBzl)-Thr(Bzl)-Ser(Bzl)-Ser(Bzl)-Glu(OBzl)-OH (43.7 g, 42.7 mmol) was then dissolved in 500 ml of DMF, cooled to 0°, and treated with Boc-Val-OSu (15.4 g, 49 mmol) and Et3N (10 ml). The mixture was stirred for 15 hours during which time more Et3N (7.9 ml) was added in several portions maintaining the reaction slightly basic. The insoluble matter was removed by filtration and the filtrate evaporated to dryness. The oily residue was dissolved in CH2Cl2, washed with 5% HOAc, H2O, dried (Na2SO4), and evaporated to a smaller volume (0.5 liter) when treated with petroleum ether. The product crystallized slowly during overnight standing. It was recrystallized from THF and i-PrOH to yield, 26.3 g (51.4%); mp 174°-177°; α]D25 =+0.84° (c, 1, THF).