Hydrochloric Acid → HCID 178455904, compound

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Reaction Steps

0.6 g. (0.5 mmoles) of Boc-Arg(Tos)-Val-Tyr-Ile-His-Pro-Ile-OH (prepared in Step 2 of Example 1) are dissolved in 5 ml. of a 8 M solution of hydrochloric acid in dioxane. The solution is allowed to stand for 20 minutes whereupon the free heptapeptide (Rf4 = 0.1) is precipitated with dry ether, filtered and washed with ether. It is immediately dissolved in 20 ml. of dimethyl formamide, the pH-value is adjusted to 8 with triethyl amine and 0.7 g. (1.9 mmoles) of Boc-OAla-OPFP are added. After 30 minutes the solution is evaporated and the residue is dissolved in 30 ml. of a 3:1 mixture of chloroform and dimethyl formamide. The solution is shaken with a 10% aqueous citric acid solution and subsequently with water. After drying and evaporation the residue is triturated with ethyl acetate, filtered and washed to give 0.55 g. (84%) of the title compound. Rf4 = 0.43; Rf5 = 0.80.

Provenance & Evidence