Hydrochloric Acid → HCID 131711280, compound

Participants

Reaction Steps

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).

Provenance & Evidence