Reaction SMILES: [NH:1]([C:21]([O:23]C(C)(C)C)=O)[C@H:2]([C:7]([NH:9][C@H:10]([C:18]([OH:20])=[O:19])[CH2:11][C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=1)=[O:8])[CH2:3][CH:4]([CH3:6])[CH3:5].Cl.C1COCC1.[NH:34]([C:108]([O:110][C:111]([CH3:114])([CH3:113])[CH3:112])=[O:109])[C@H:35]([C:45]([NH:47][C@H:48]([C:54]([NH:56][C@H:57]([C:68]([N:70]1[CH2:107][CH2:106][CH2:105][C@H:71]1[C:72]([NH:74][C@H:75]([C:80]([NH:82][C@H:83]([C:87]([NH:89][C@H:90](C(NN)=O)[C@@H:91]([CH3:100])[O:92][CH2:93][C:94]1[CH:99]=[CH:98][CH:97]=[CH:96][CH:95]=1)=[O:88])[CH:84]([CH3:86])[CH3:85])=[O:81])[CH2:76][CH:77]([CH3:79])[CH3:78])=[O:73])=[O:69])[C@@H:58]([CH3:67])[O:59][CH2:60][C:61]1[CH:66]=[CH:65][CH:64]=[CH:63][CH:62]=1)=[O:55])[CH2:49][CH2:50][C:51](=[O:53])[NH2:52])=[O:46])[CH2:36][O:37][CH2:38][C:39]1[CH:44]=[CH:43][CH:42]=[CH:41][CH:40]=1.[N-]=[N+]=[N-]>CN(C=O)C.CC(O)=O.CCN(CC)CC>[NH:34]([C:108]([O:110][C:111]([CH3:114])([CH3:113])[CH3:112])=[O:109])[C@H:35]([C:45]([NH:47][C@H:48]([C:54]([NH:56][C@H:57]([C:68]([N:70]1[CH2:107][CH2:106][CH2:105][C@H:71]1[C:72]([NH:74][C@H:75]([C:80]([NH:82][C@H:83]([C:87]([NH:89][C@H:90]([C:21]([NH:1][C@H:2]([C:7]([NH:9][C@H:10]([C:18]([OH:20])=[O:19])[CH2:11][C:12]1[CH:13]=[CH:14][CH:15]=[CH:16][CH:17]=1)=[O:8])[CH2:3][CH:4]([CH3:5])[CH3:6])=[O:23])[C@@H:91]([CH3:100])[O:92][CH2:93][C:94]1[CH:95]=[CH:96][CH:97]=[CH:98][CH:99]=1)=[O:88])[CH:84]([CH3:86])[CH3:85])=[O:81])[CH2:76][CH:77]([CH3:79])[CH3:78])=[O:73])=[O:69])[C@@H:58]([CH3:67])[O:59][CH2:60][C:61]1[CH:66]=[CH:65][CH:64]=[CH:63][CH:62]=1)=[O:55])[CH2:49][CH2:50][C:51](=[O:53])[NH2:52])=[O:46])[CH2:36][O:37][CH2:38][C:39]1[CH:40]=[CH:41][CH:42]=[CH:43][CH:44]=1
Reactant: CC(C)C[C@H](NC(=O)[C@@H]1CCCN1C(=O)[C@@H](NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](COCc1ccccc1)NC(=O)OC(C)(C)C)[C@@H](C)OCc1ccccc1)C(=O)N[C@H](C(=O)N[C@H](C(=O)NN)[C@@H](C)OCc1ccccc1)C(C)C
Reactant: CC(C)C[C@H](NC(=O)OC(C)(C)C)C(=O)N[C@@H](Cc1ccccc1)C(=O)O
Agent: Cl
Agent: [N-]=[N+]=[N-]
Solvent: CCN(CC)CC
Solvent: CN(C)C=O
Solvent: C1CCOC1
Product: CC(C)C[C@H](NC(=O)[C@@H](NC(=O)[C@@H](NC(=O)[C@H](CC(C)C)NC(=O)[C@@H]1CCCN1C(=O)[C@@H](NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](COCc1ccccc1)NC(=O)OC(C)(C)C)[C@@H](C)OCc1ccccc1)C(C)C)[C@@H](C)OCc1ccccc1)C(=O)N[C@@H](Cc1ccccc1)C(=O)O
Temperature: 4 °C
Reaction time: 96 h

Procedure:
Boc-Leu-Phe-OH (XVI) (0.53 g, 1.4 mmol) was deblocked with 4 N HCl/THF (17.5 ml) and worked up as in Example 9 to yield the white crystalline salt. Boc-Ser(Bzl)-Gln-Thr(Bzl)-Pro-Leu-Val-Thr(Bzl)-NHNH2 (XV) (0.79 g, 0.7 mmol) in DMF (10 ml) was converted into the azide by treatment with 2.8 N HCl/THF (1.25 ml) and i-amylnitrite (0.14 ml) at -20° C for 25 min. The temperature was lowered to -30° C, Et3N (0.49 ml) was added followed by a pre-cooled mixture of the hydrochloride salt of compound (XVI) which was pretreated with Et3N. The mixture was stirred for 1.5 hr at -15° C and for 4 days at 4° C. It was acidified with glacial AcOH, evaporated to a smaller volume, and treated with 1 M AcOH. The precipitated solid was filtered and washed with H2O. The crude product (0.92 g) mp 194°- 196.5° C, after trituration with EtOAc, was recrystallized from hot MeOH to provide (XVII) in fine crystals, 0.51 g (53%); mp 205°-207° C; [α]D25 -20.1° (C 1, DMF). Anal. Calcd for C73H102N10O16 (1375.70): C, 63.73; H, 7.47; N, 10.18. Found: C, 63.26; H, 7.43; N, 10.23. Amino Acid Analysis (6 N HCl-phenol, 100° C, 24 hr): Thr2.00, Ser0.91, Glu1.03, Pro1.05, Val0.99, Leu2.08, Phe1.00.