Hydrochloric Acid → HCID 178445977, compound

Participants

Reaction Steps

721 mg of Z-Arg-Arg-Pro-Phe-His-OH×3 HCl (see stage 4.4) (containing 24% by weight of NaCl), 176 mg of H-Sta-β-Ala-His-NH2, 91 mg of HOBt×H2O and 50 μl of N-methylmorpholine are dissolved in 5 ml of DMF. After cooling to 0°, 132 mg of DCCI are added and then the whole is stirred for 6 hours at 0° and left to stand overnight at room temperature. The DCH which has crystallised out is filtered off, the filtrate is concentrated to dryness and the residue is heated for 1 hour at 60° in 14 ml of methanol/glacial acetic acid/H2O (94:3:3). The solution is concentrated to 3 ml and the crude product is precipitated by the addition of 30 ml of diisopropyl ether. In order to convert it into the acetate, the product is dissolved in 5 ml of 0.05N acetic acid, a small amount of insoluble material is filtered off and the solution is filtered slowly through a column (φ=1.2 cm, length=10 cm) of weakly basic ion exchanger in the acetate form (Merck II) equilibrated in 0.05N acetic acid. The eluate is concentrated to approximately 3 ml and lyophilised. Purification is effected by means of Craig partitioning over 750 stages in the system n-pentanol/glacial acetic acid/H2O (4:1:5); K=0.13. The chromatographically pure fractions are combined, concentrated to dryness and the residue is dissolved in 3 ml of H2O and lyophilised. Z-Arg-Arg-Pro-Phe-His-Sta-β-Ala-His-NH2 (acetate form) is obtained in the form of an amorphous, water-soluble powder; Rf (D)=0.17; Rf (M)=0.30; Rf (O)=0.25.

Provenance & Evidence