Reaction SMILES: [CH3:1][C:2]1[C:7]([O:8][CH3:9])=[C:6]([OH:10])[C:5]2[C@H:11]3[N:33]([CH3:34])[C@@H:31]([CH2:32][C:4]=2[CH:3]=1)[C@H:30](C#N)[N:29]1[C@H:12]3[C@@H:13]2[S:43][CH2:42][C@:41]3([NH:52][CH2:51][CH2:50][C:49]4[C:44]3=[CH:45][C:46]([O:54][CH3:55])=[C:47]([OH:53])[CH:48]=4)[C:39](=[O:40])[O:38][CH2:37][C@H:28]1[C:15]1[C:16]3[O:27][CH2:26][O:25][C:17]=3[C:18]([CH3:24])=[C:19]([O:20][C:21]([CH3:23])=[O:22])[C:14]2=1.[Cl-].[Na+].C(=O)([O-])[OH:59].[Na+]>C(#N)C.O.[N+]([O-])([O-])=O.[Ag+]>[CH3:1][C:2]1[C:7]([O:8][CH3:9])=[C:6]([OH:10])[C:5]2[C@H:11]3[N:33]([CH3:34])[C@@H:31]([CH2:32][C:4]=2[CH:3]=1)[C@H:30]([OH:59])[N:29]1[C@H:12]3[C@H:13]2[S:43][CH2:42][C@:41]3([NH:52][CH2:51][CH2:50][C:49]4[C:44]3=[CH:45][C:46]([O:54][CH3:55])=[C:47]([OH:53])[CH:48]=4)[C:39](=[O:40])[O:38][CH2:37][C@@H:28]1[C:15]1[C:16]3[O:27][CH2:26][O:25][C:17]=3[C:18]([CH3:24])=[C:19]([O:20][C:21]([CH3:23])=[O:22])[C:14]2=1
Reactant: COc1cc2c(cc1O)CCN[C@]21CS[C@@H]2c3c(OC(C)=O)c(C)c4c(c3[C@H](COC1=O)N1[C@@H]2[C@H]2c3c(cc(C)c(OC)c3O)C[C@@H]([C@@H]1C#N)N2C)OCO4
Reactant: O=C([O-])O
Agent: [Ag+]
Agent: O=[N+]([O-])[O-]
Agent: [Cl-]
Solvent: O
Solvent: CC#N
Product: COc1cc2c(cc1O)CCN[C@]21CS[C@H]2c3c(OC(C)=O)c(C)c4c(c3[C@@H](COC1=O)N1[C@@H]2[C@H]2c3c(cc(C)c(OC)c3O)C[C@@H]([C@@H]1O)N2C)OCO4
Temperature: 23 °C
Reaction time: 19 h
Yield: 92 %

Procedure:
To a solution of ecteinascidin 770 (22 mg, 0.0285 mmol) in acetonitrile and water (3:2, v/v, 4 ml) was added silver nitrate (100 mg, 20 equiv). The suspension was stirred at 23° C. for 19 hours at which time a mixture of saturated aqueous sodium chloride solution (1 ml) and saturated aqueous sodium hydrogen carbonate solution (1 ml) was added. The mixture was stirred vigorously at 23° C. for 10 min before it was partitioned between saturated aqueous sodium chloride solution and saturated aqueous sodium hydrogen carbonate solution (20 ml, v/v, 1:1) and extracted with ethyl acetate (3×100 ml). The combined organic layer was dried over sodium sulfate, concentrated, and the residue was purified by flash column chromatography (60% EtOAc in heptane) to afford ecteinascidin 743 (20 mg, 92%) as a pale yellow film. [α]D2 4.5−53.8° (c=0.65, CHCl3). IR (neat film) 3433, 2935, 1762, 1741, 1586, 1511, 1502, 1460, 1452, 1370, 1243, 1087, 1028, 1002, 957 cm−1; 1H NMR (300 MHz, CDCl3) 6.59 (s, 1H), 65 (s, 1H), 6.44 (s, 1H), 6.01 (s, 1H), 5.93 (s, 1H), 5.72 (bs, 1H), 5.12 (d, J=11.2 Hz, 1H), 4.80 (s, 1H), 4.47 (d, J=3.0 Hz, 1H), 4.46 (s, 1H), 4.15 (d, J=4.0 Hz, 1H), 4.03 (dd, J=11.2 2.1 Hz, 1H), 3.78 (s, 3H), 3.60 (s, 3H), 3.56 (d, J=4.9 Hz, 1H), 3.17-3.22 (m, 1H), 3.12 (ddd, J=14.1, 10.1, 4.2 Hz, 1H), 2.75-2.93 (m, 3H), 2.59 (ddd, J=15.6, 9.5, 5.3 Hz, 1H), 2.46 (dt, J=15.8, 3.5 Hz, 1H), 2.34 (d, J=17.5 Hz, 1H), 2.31 (s, 3H), 2.25 (s, 3H), 2.16 (s, 3H), 2.08-2.15 (m, 1H), 2.02 (s, 3H); 13C NMR (125.7 MHz, CDCl3) δ 172.55, 168.34, 147.69, 145.13, 144.44, 144.28, 142.97, 141.29, 140.51, 131.55, 129.19, 129.12, 126.06, 121.87, 120.96, 118.00, 115.96, 114.06, 112.53, 109.84, 101.66, 82.11, 64.68, 61.37, 60.35, 57.80, 57.74, 55.98, 55.15, 54.94, 42.22, 42.16, 41.44, 39.71, 28.85, 24.06, 20.43, 15.80, 9.67; HRMS (MALDI+) m/z: Calc. for C39H42N3O10S (M−OH)+ 744.2605 and C39H44N3O11S (M+H)+ 762.2719, found 744.2590, 762.2696.