C(OC([N:8]1[CH2:13][CH2:12][N:11]([CH2:14][C:15]([NH:17][CH2:18][C:19]([NH:21][C@H:22]([C:30]([NH:32][CH3:33])=[O:31])[CH2:23][C:24]2[CH:29]=[CH:28][CH:27]=[CH:26][CH:25]=2)=[O:20])=[O:16])[C:10](=[O:34])[CH:9]1[CH2:35][C:36]1[CH:41]=[CH:40][C:39]([OH:42])=[CH:38][CH:37]=1)=O)(C)(C)C.FC(F)(F)C(O)=O>>[OH:42][C:39]1[CH:38]=[CH:37][C:36]([CH2:35][CH:9]2[NH:8][CH2:13][CH2:12][N:11]([CH2:14][C:15]([NH:17][CH2:18][C:19]([NH:21][C@H:22]([C:30]([NH:32][CH3:33])=[O:31])[CH2:23][C:24]3[CH:29]=[CH:28][CH:27]=[CH:26][CH:25]=3)=[O:20])=[O:16])[C:10]2=[O:34])=[CH:41][CH:40]=1Piperazinone acetyl-gly-phe-NHCH3 11a (0.58 g, 1.0×10-3 mole) and trifluoroacetic acid are stirred at room temperature for 1/2 hour. The solvent is then evaporated and the residue dissolved in CH2Cl2. The CH2Cl2 solution is washed in turn with saturated aqueous NaHCO3 and saturated aqueous NaCl before being dried over Na2SO4. Filtration of the drying agent and evaporation of the filtrate give 12a which is purified by chromatography and the structure corroborated by NMR. NMR (Acetone - d6)δ (d, 3, methyl amide), 3.0-4.3 (m, 14, methylenes and phenolic-OH), 4.53 (m, 1, phenylalanine methine), 6.88 (8, 4, aromatic), 7.25 (s, 5, aromatic), 7.6-8.0 (m, 3, amide NH's).
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