Reaction SMILES: [CH2:1]([O:8][CH2:9][O:10][C@H:11]([CH3:74])[C@H:12]([OH:73])[CH2:13][C@H:14]1[O:19][C@:18]([C:22]([CH3:57])([CH3:56])/[CH:23]=[CH:24]/[C@@H:25]2[O:30][C@H:29]([CH2:31][C@@H:32]3[O:37][C@H:36]([CH2:38][C@@H:39]([O:44][CH2:45][C:46]4[CH:51]=[CH:50][C:49]([O:52][CH3:53])=[CH:48][CH:47]=4)[CH2:40][C:41]([OH:43])=[O:42])[CH2:35][C@H:34]([OH:54])[CH2:33]3)[CH2:28][C:27](=[CH2:55])[CH2:26]2)([O:20][CH3:21])[C@@H:17]([O:58][C:59](=[O:67])[CH2:60][CH2:61][CH2:62][CH2:63][CH2:64][CH2:65][CH3:66])/[C:16](=[CH:68]/[C:69]([O:71][CH3:72])=[O:70])/[CH2:15]1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.[Si:75](Cl)([CH2:80][CH3:81])([CH2:78][CH3:79])[CH2:76][CH3:77]>C(Cl)Cl.CN(C1C=CN=CC=1)C>[CH2:1]([O:8][CH2:9][O:10][C@H:11]([CH3:74])[C@H:12]([OH:73])[CH2:13][C@H:14]1[O:19][C@:18]([C:22]([CH3:57])([CH3:56])/[CH:23]=[CH:24]/[C@@H:25]2[O:30][C@H:29]([CH2:31][C@@H:32]3[O:37][C@H:36]([CH2:38][C@@H:39]([O:44][CH2:45][C:46]4[CH:47]=[CH:48][C:49]([O:52][CH3:53])=[CH:50][CH:51]=4)[CH2:40][C:41]([OH:43])=[O:42])[CH2:35][C@H:34]([O:54][Si:75]([CH2:80][CH3:81])([CH2:78][CH3:79])[CH2:76][CH3:77])[CH2:33]3)[CH2:28][C:27](=[CH2:55])[CH2:26]2)([O:20][CH3:21])[C@@H:17]([O:58][C:59](=[O:67])[CH2:60][CH2:61][CH2:62][CH2:63][CH2:64][CH2:65][CH3:66])/[C:16](=[CH:68]/[C:69]([O:71][CH3:72])=[O:70])/[CH2:15]1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1
Reactant: CC[Si](Cl)(CC)CC
Reactant: C=C1C[C@@H](C[C@H]2C[C@@H](O)C[C@@H](C[C@H](CC(=O)O)OCc3ccc(OC)cc3)O2)O[C@@H](/C=C/C(C)(C)[C@]2(OC)O[C@H](C[C@@H](O)[C@@H](C)OCOCc3ccccc3)C/C(=C\C(=O)OC)[C@@H]2OC(=O)CCCCCCC)C1
Agent: CN(C)c1ccncc1
Solvent: ClCCl
Product: C=C1C[C@@H](C[C@H]2C[C@@H](O[Si](CC)(CC)CC)C[C@@H](C[C@H](CC(=O)O)OCc3ccc(OC)cc3)O2)O[C@@H](/C=C/C(C)(C)[C@]2(OC)O[C@H](C[C@@H](O)[C@@H](C)OCOCc3ccccc3)C/C(=C\C(=O)OC)[C@@H]2OC(=O)CCCCCCC)C1
Temperature: -15 °C
Reaction time: 1.5 h
Yield: 76 %

Procedure:
To a stirring solution of alcohol 21 (3.0 mg, 0.0029 mmol, 1.0 equiv) in CH2Cl2 (116 μL, 0.025 M) in a 4 mL reaction vial at rt was added DMAP (1.6 mg, 0.013 mmol, 4.5 equiv). The reaction was cooled to −15° C., then a 1.0 M solution of TESCl in CH2Cl2 (6.1 μL, 0.0061 mmol, 2.1 equiv) was added by syringe. Stirring was continued for 90 min. The reaction was then quenched by addition of 1 mL of saturated aqueous NaHCO3 solution, and the mixture was partitioned between 10 mL of EtOAc and 5 mL of saturated aqueous NaHCO3 solution. The aqueous phase was separated and extracted with EtOAc (3×10 mL). The combined organic phases were dried over Na2SO4 and concentrated under reduced pressure. Purification was accomplished using flash chromatography with a 0.6×4 cm silica gel column, eluting with 5% MeOH/35% EtOAc/hexanes, collecting 6×50 mm test tube fractions. The product containing fractions (11-25) were combined and concentrated under reduced pressure to provide pure product 11 (2.5 mg, 76%) as a colorless oil. Rf=0.63 (MeOH/EtOAc/Hexanes=5:35:60); [α]D20=+5 (c=0.085, CHCl3); 500 MHz 1H NMR (CDCl3) δ 7.37-7.30 (m, 5H), 7.26 (d, J=8.8 Hz, 2H), 6.89 (d, J=8.8 Hz, 2H), 5.98 (d, J=15.6 Hz, 1H), 5.88 (s, 1H), 5.56 (s, 1H), 5.42 (dd, J=16.1, 6.3 Hz, 1H), 4.90 (d, J=6.8 Hz, 1H), 4.85 (d, J=6.8 Hz, 1H), 4.70-4.60 (m, 4H), 4.57 (d, J=10.7 Hz, 1H), 4.47 (d, J=10.7 Hz, 1H), 4.26-4.18 (m, 1H), 4.15-4.05 (m, 1H), 3.90-3.85 (m, 1H), 3.81 (s, 3H), 3.74-3.62 (m, 6H), 3.56-3.40 (m, 4H), 3.34 (s, 3H), 2.62 (dddd, J=15.6, 15.6, 15.6, 5.4 Hz, 2H), 2.35 (ddd, J=7.3, 7.3, 2.9 Hz, 3H), 2.28 (d, J=13.2 Hz, 1H), 2.20 (d, J=12.2 Hz, 1H), 2.10-2.00 (m, 2H), 2.00-1.88 (m, 3H), 1.86-1.80 (m, 1H), 1.80-1.55 (m, 7H), 1.34-1.22 (m, 10H), 1.12 (s, 6H), 0.95 (t, J=7.8 Hz, 9H), 0.88 (m, 6H), 0.60 (q, J=7.8 Hz, 6H); 125 MHz 13C NMR (CDCl3) δ 174.0, 172.3, 166.8, 159.5, 153.2, 144.3, 139.2, 139.2, 137.7, 129.6, 128.7, 128.1, 128.1, 126.9, 116.8, 114.1, 109.1, 102.8, 93.9, 79.7, 78.0, 77.4, 75.7, 73.6, 72.4, 72.2, 72.1, 71.1, 70.1, 68.6, 68.2, 55.5, 51.4, 51.4, 46.2, 42.9, 42.3, 42.1, 40.8, 40.7, 39.8, 34.6, 31.9, 31.8, 29.9, 29.3, 29.2, 25.0, 24.6, 23.6, 22.9, 22.8, 17.0, 14.4, 7.1, 5.2; 125 MHz DEPT 13C NMR (CDCl3) CH3 δ 55.5, 51.4, 51.4, 24.6, 23.6, 17.0, 14.4, 7.1; CH2 δ 109.1, 93.9, 72.4, 70.1, 42.9, 42.3, 42.1, 40.8, 40.7, 39.8, 34.6, 31.9, 29.9, 29.3, 29.2, 25.0, 23.6, 22.9, 22.8, 5.2; CH δ 139.2, 139.2, 129.6, 128.7, 128.1, 128.1, 126.9, 114.1, 79.7, 78.0, 75.7, 73.6, 72.4, 72.2, 72.1, 71.1, 68.6, 68.2; C δ 174.0, 172.3, 166.8, 159.5, 153.2, 144.3, 137.7, 116.8, 102.8, 46.2; IR (neat) 2930, 1719, 1513, 1459, 1380, 1247, 1154, 1040, 822, 742 cm−1; HRMS (ESI/APCI) calcd for C64H98O16NaSi (M+Na) 1173.6522. found 1173.6545.