Reaction SMILES: [C:1]([O:5][C:6](=[O:79])[CH2:7][N:8]([CH2:71][C:72](=[O:78])[O:73][C:74]([CH3:77])([CH3:76])[CH3:75])[C:9](=[O:70])[CH2:10][N:11]1[CH:15]=[CH:14][N:13]=[C:12]1[CH2:16][N:17]([CH2:59][C:60]1[CH:65]=[CH:64][C:63]([O:66][CH2:67][C:68]#[CH:69])=[CH:62][CH:61]=1)[CH2:18][CH2:19][CH2:20][CH2:21][CH2:22][C:23](=[O:58])[NH:24][CH2:25][CH2:26][CH2:27][CH2:28][C@@H:29]([C:51]([O:53][C:54]([CH3:57])([CH3:56])[CH3:55])=[O:52])[NH:30][C:31](=[O:50])[NH:32][C@H:33]([C:43]([O:45][C:46]([CH3:49])([CH3:48])[CH3:47])=[O:44])[CH2:34][CH2:35][C:36]([O:38][C:39]([CH3:42])([CH3:41])[CH3:40])=[O:37])([CH3:4])([CH3:3])[CH3:2].[N:80]([CH2:83][CH2:84][CH2:85][NH:86][C:87](=[O:125])[CH2:88][N:89]1[CH2:100][CH2:99][N:98]([CH2:101][C:102]([O:104][C:105]([CH3:108])([CH3:107])[CH3:106])=[O:103])[CH2:97][CH2:96][N:95]([CH2:109][C:110]([O:112][C:113]([CH3:116])([CH3:115])[CH3:114])=[O:111])[CH2:94][CH2:93][N:92]([CH2:117][C:118]([O:120][C:121]([CH3:124])([CH3:123])[CH3:122])=[O:119])[CH2:91][CH2:90]1)=[N+:81]=[N-:82]>C1COCC1.O.CCOC(C)=O.[Cu].[O-]S([O-])(=O)=O.[Cu+2]>[C:74]([O:73][C:72](=[O:78])[CH2:71][N:8]([CH2:7][C:6](=[O:79])[O:5][C:1]([CH3:2])([CH3:3])[CH3:4])[C:9](=[O:70])[CH2:10][N:11]1[CH:15]=[CH:14][N:13]=[C:12]1[CH2:16][N:17]([CH2:59][C:60]1[CH:61]=[CH:62][C:63]([O:66][CH2:67][C:68]2[N:82]=[N:81][N:80]([CH2:83][CH2:84][CH2:85][NH:86][C:87](=[O:125])[CH2:88][N:89]3[CH2:90][CH2:91][N:92]([CH2:117][C:118](=[O:119])[O:120][C:121]([CH3:122])([CH3:123])[CH3:124])[CH2:93][CH2:94][N:95]([CH2:109][C:110](=[O:111])[O:112][C:113]([CH3:115])([CH3:116])[CH3:114])[CH2:96][CH2:97][N:98]([CH2:101][C:102]([O:104][C:105]([CH3:108])([CH3:107])[CH3:106])=[O:103])[CH2:99][CH2:100]3)[CH:69]=2)=[CH:64][CH:65]=1)[CH2:18][CH2:19][CH2:20][CH2:21][CH2:22][C:23](=[O:58])[NH:24][CH2:25][CH2:26][CH2:27][CH2:28][C@@H:29]([C:51]([O:53][C:54]([CH3:55])([CH3:56])[CH3:57])=[O:52])[NH:30][C:31](=[O:50])[NH:32][C@H:33]([C:43]([O:45][C:46]([CH3:47])([CH3:48])[CH3:49])=[O:44])[CH2:34][CH2:35][C:36]([O:38][C:39]([CH3:42])([CH3:41])[CH3:40])=[O:37])([CH3:77])([CH3:76])[CH3:75]
Reactant: C#CCOc1ccc(CN(CCCCCC(=O)NCCCC[C@H](NC(=O)N[C@@H](CCC(=O)OC(C)(C)C)C(=O)OC(C)(C)C)C(=O)OC(C)(C)C)Cc2nccn2CC(=O)N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)cc1
Reactant: CC(C)(C)OC(=O)CN1CCN(CC(=O)NCCCN=[N+]=[N-])CCN(CC(=O)OC(C)(C)C)CCN(CC(=O)OC(C)(C)C)CC1
Agent: [Cu+2]
Agent: [Cu]
Agent: O=S(=O)([O-])[O-]
Solvent: CCOC(C)=O
Solvent: O
Solvent: C1CCOC1
Product: CC(C)(C)OC(=O)CC[C@H](NC(=O)N[C@@H](CCCCNC(=O)CCCCCN(Cc1ccc(OCc2cn(CCCNC(=O)CN3CCN(CC(=O)OC(C)(C)C)CCN(CC(=O)OC(C)(C)C)CCN(CC(=O)OC(C)(C)C)CC3)nn2)cc1)Cc1nccn1CC(=O)N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)C(=O)OC(C)(C)C)C(=O)OC(C)(C)C
Temperature: 25 °C
Reaction time: 8 h
Yield: 13.7 %

Procedure:
To a solution of (14S,18S)-tri-tert-butyl 1-(1-(2-(bis(2-(tert-butoxy)-2-oxoethyl)amino)-2-oxoethyl)-1H-imidazol-2-yl)-8,16-dioxo-2-(4-(prop-2-yn-1-yloxy)benzyl)-2,9,15,17-tetraazaicosane-14,18,20-tricarboxylate (145 mg, 0.13 mmol), tri-tert-butyl 2,2′,2″-(10-(2-((3-azidopropyl)amino)-2-oxoethyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetate (59 mg, 0.090 mmol) in THF (5.0 mL) and water (1.0 mL) was added copper powder (6.4 mg) and 1 N CuSO4 (0.01 mL). The mixture was stirred at room temperature for overnight under nitrogen, diluted with EtOAc, washed with an aqueous saturated solution of EDTA. The solvent was evaporated under reduce pressure to afford a residue, which was purified by Biotage SP4 to afford ((14S,18S)-tri-tert-butyl 1-(1-(2-(bis(2-(tert-butoxy)-2-oxoethyl)amino)-2-oxoethyl)-1H-imidazol-2-yl)-8,16-dioxo-2-(4-((1-(3-(2-(4,7,10-tris(2-(tert-butoxy)-2-oxoethyl)-1,4,7,10-tetraazacyclododecan-1-yl)acetamido)propyl)-1H-1,2,3-triazol-4-yl)methoxy)benzyl)-2,9,15,17-tetraazaicosane-14,18,20-tricarboxylate (21.8 mg). MS (ESI), 883.2 (M/2+H)′.