Reaction SMILES: [C:1]([O:4][C@@H:5]1[C@@H:14]([O:15][C:16](=[O:18])[CH3:17])[C@H:13]([O:19][C@H:20]2[O:77][C@H:76]([CH2:78][O:79][C:80](=[O:82])[CH3:81])[C@@H:31]([O:32][C@H:33]3[O:50][C@H:49]([CH2:51][O:52][C@H:53]4[O:70][C@H:69]([CH2:71][O:72][C:73](=[O:75])[CH3:74])[C@@H:64]([O:65][C:66](=[O:68])[CH3:67])[C@H:59]([O:60][C:61](=[O:63])[CH3:62])[C@H:54]4[O:55][C:56](=[O:58])[CH3:57])[C@@H:44]([O:45][C:46](=[O:48])[CH3:47])[C@H:39]([O:40][C:41](=[O:43])[CH3:42])[C@H:34]3[O:35][C:36](=[O:38])[CH3:37])[C@H:26]([O:27][C:28](=[O:30])[CH3:29])[C@H:21]2[O:22][C:23](=[O:25])[CH3:24])[C@@H:12]([CH2:83][O:84][C:85](=[O:87])[CH3:86])[O:11][C@H:6]1[O:7][CH2:8][CH2:9]Br)(=[O:3])[CH3:2].[SH:88][CH2:89][CH2:90][CH2:91][CH2:92][CH2:93][CH2:94][CH2:95][CH2:96][CH2:97][CH2:98][C:99]([O:101][CH3:102])=[O:100].C(=O)([O-])[O-].[Cs+].[Cs+].CN(C)C=O>ClCCl>[C:1]([O:4][C@@H:5]1[C@@H:14]([O:15][C:16](=[O:18])[CH3:17])[C@H:13]([O:19][C@H:20]2[O:77][C@H:76]([CH2:78][O:79][C:80](=[O:82])[CH3:81])[C@@H:31]([O:32][C@H:33]3[O:50][C@H:49]([CH2:51][O:52][C@H:53]4[O:70][C@H:69]([CH2:71][O:72][C:73](=[O:75])[CH3:74])[C@@H:64]([O:65][C:66](=[O:68])[CH3:67])[C@H:59]([O:60][C:61](=[O:63])[CH3:62])[C@H:54]4[O:55][C:56](=[O:58])[CH3:57])[C@@H:44]([O:45][C:46](=[O:48])[CH3:47])[C@H:39]([O:40][C:41](=[O:43])[CH3:42])[C@H:34]3[O:35][C:36](=[O:38])[CH3:37])[C@H:26]([O:27][C:28](=[O:30])[CH3:29])[C@H:21]2[O:22][C:23](=[O:25])[CH3:24])[C@@H:12]([CH2:83][O:84][C:85](=[O:87])[CH3:86])[O:11][C@H:6]1[O:7][CH2:8][CH2:9][S:88][CH2:89][CH2:90][CH2:91][CH2:92][CH2:93][CH2:94][CH2:95][CH2:96][CH2:97][CH2:98][C:99]([O:101][CH3:102])=[O:100])(=[O:3])[CH3:2]
Reactant: CC(=O)OC[C@H]1O[C@H](OC[C@H]2O[C@H](O[C@H]3[C@H](OC(C)=O)[C@@H](OC(C)=O)[C@@H](O[C@H]4[C@H](OC(C)=O)[C@@H](OC(C)=O)[C@H](OCCBr)O[C@@H]4COC(C)=O)O[C@@H]3COC(C)=O)[C@H](OC(C)=O)[C@@H](OC(C)=O)[C@@H]2OC(C)=O)[C@H](OC(C)=O)[C@@H](OC(C)=O)[C@@H]1OC(C)=O
Reactant: COC(=O)CCCCCCCCCCS
Agent: O=C([O-])[O-]
Agent: [Cs+]
Solvent: CN(C)C=O
Solvent: ClCCl
Product: COC(=O)CCCCCCCCCCSCCO[C@@H]1O[C@H](COC(C)=O)[C@@H](O[C@H]2O[C@H](COC(C)=O)[C@@H](O[C@H]3O[C@H](CO[C@H]4O[C@H](COC(C)=O)[C@@H](OC(C)=O)[C@H](OC(C)=O)[C@H]4OC(C)=O)[C@@H](OC(C)=O)[C@H](OC(C)=O)[C@H]3OC(C)=O)[C@H](OC(C)=O)[C@H]2OC(C)=O)[C@H](OC(C)=O)[C@H]1OC(C)=O
Yield: 50 %

Procedure:
Compound 93 (431 mg, 0.33 mmol), methyl 11-mercaptoundecanoate (105, 114 mg, 0.49 mmol), cesium carbonate (128 mg, 0.39 mmol) and N,N-dimethylformamide (3 ml) were stirred at room temperature for 15 h. The mixture was diluted with dichloromethane, washed with water (neutralization with Duolite H+ resin facilitated the phase separation), and dried (Na2SO4). The solvent was removed and the residue was chromatographed (SiO2, ethyl acetate:isooctane 2:1) to give 95 (243 mg, 50%). [α]D24 +91° (c 4.4, chloroform). 1H-NMR (CDCl3, Me4Si) δ 5.36, 5.28, 5.19 (3d, each 1H, J=3.8, 4.1 and 3.6 Hz, H1', H1", H1"'), 4.57 (d, 1H, J=7.9 Hz, H1), 3.67 (s, 3H, MeO), 2.68, 2.52, 2.31 (3 t, each 2H, J=7 Hz, CH2 --S--CH2 and CH2CO). 13C-NMR (CDCl3, Me4Si) δ 174.1, 170.4-169.1, 100.1 (Cl), 95.6, 95.5, 95.1 (Cl', Cl", Cl"'), 75.0, 73.6, 72.5, 71.9, 71.5, 70.5, 70.2, 69.9, 69.7, 69.6, 69.2, 69.1, 69.1, 69.1, 68.7, 68.3, 67.2, 65.1, 62.9, 62.8, 61.6, 51.2, 33.9, 32.3, 31.1, 29.5, 29.2, 29.1, 29.0, 29.0, 28.9, 28.6, 24.7, 20.7-20.4.