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40 Chapter 2 2 Para-methoxyphenyl 2,3,6-tri-O-benzyl-β-D-galactopyranosyl-(1 → 4)-2,3,6-tri-O- benzyl-β-D-gluco-pyranoside (12a). Compound 25 36 (8.1 g, 8.2 mmol) was s�rred in DCM (50 mL) with 4 Å molecular sieves for 3 h. The mixture was cooled to -78°C and a�er adding Et 3 SiH (6.5 mL, 41 mmol) s�rring was con�nued for another 30 min. TfOH (1.45 mL, 16.4 mmol) was introduced and a�er 2.5 h, the reac�on mixture was quenched with Et 3 N. The resul�ng mixture was filtered over Celite and the filtrate was washed with H 2 O, sat. aq. NaHCO 3 , dried (Na 2 SO 4 ), filtered and concentrated in vacuo . The obtained residue was purified by silica gel chromatography using Toluene:EtOAc (1:0 to 20:1 v/v) as the eluent to afford compound 12a (2.28g, 64 %). 1 H NMR (400 MHz, CDCl 3 ) δ 7.54 – 7.14 (30H, m, Ar-H), 7.02 (2H, d, J = 9.1 Hz, OMP), 6.79 (2H, d, J = 9.1 Hz, OMP), 5.00 (2H, t, J = 10.7 Hz, CH 2 , Bn), 4.85 (1H, d, J = 7.4 Hz, H-1, Glc-I), 4.83 – 4.64 (6H, m, 3x, CH 2 , Bn), 4.53 – 4.35 (5H, m, 2x CH 2 , Bn; H-1, Gal-II), 4.06 – 3.96 (2H, m, H-4, Gal-II; H-5 Gal-II), 3.82 – 3.74 (4H, m, CH 3 , OMP; H-6 Glc-I), 3.72 – 3.57 (4H, m, H-4, Glc-I; H-6a, Gal-II; H-2, Glc-I; H-2, Gal-II), 3.52 – 3.45 (2H, m, H-5, Glc-I; H6-b, Gal-II), 3.40 (1H, dd, J = 9.3, 3.4 Hz, H-3, Gal-II), 3.35 (1H, t, H-3, Glc-I), 2.39 (1H, d, J = 2.0 Hz, OH). 13 C NMR (101 MHz, CDCl 3 ) δ 155.2 (C, OMP), 151.6 (C, OMP), 139.0 (C, OBn), 138.5 (C, OBn), 138.4 (C, OBn), 138.3 (C, OBn, 138.2 (C, OBn), 137.9 (C, OBn), 128.43, 128.34, 128.28, 128.25, 128.20, 128.08, 128.04, 127.83, 127.78, 127.73, 127.62, 127.59, 127.54, 127.40, 127.25, 118.4 (2x CH, OMP), 114.5 (2x CH, OMP), 102.8 (C-1, Glc-I), 102.6 (C-1, Gal-II), 82.9 (C-4, Glc-I), 81.6 (C-2, Glc-I), 81.1 (C-3, Gal-II), 79.4 (C-2, Gal-II), 77.2 (C-5, Gal-II), 75.4 (CH 2 ), 75.3 (2x CH 2 ), 75.1 (C-5, Glc-I), 73.5 (CH 2 ), 73.1 (CH 2 ), 72.8 (C-3, Glc-I), 72.0 (CH 2 ), 68.4 (C-6, Glc-I), 68.3 (C-6, Gal-II), 66.1 (C-4, Gal-II), 55.6 (CH 3 , OMP). ESI HRMS (m/z): [M + NH 4 ] + calcd for C 61 H 64 O 12 , 1006.4736; found 1006.4750. N-(Benzyl)-benzyloxycarbonyl-5-aminopentan-1-ol (28). The protected aminopentanol linker was synthesized as described before. 37 N-(Benzyl)-benzyloxycarbonyl-5-aminopentyl 2,3-di-O-benzyl-4,6-O-benzylidene-β- D-galactopyranosyl-(1 → 4)-2,3,6-tri-O-benzyl-β-D-glucopyranoside (27). Oven-dried (90°C, 1.5 h) ceric ammonium nitrate (1.67 g, 3.0 mmol) was added to a s�rring solu�on of compound 25 36 (2.0 g, 2.0 mmol) in CH 3 CN/H 2 O (40/10 mL) at 0°C. A�er 30 min, the mixture was diluted with DCM, washed with sat. aq. NaHCO 3 (2 x), brine, dried (Na 2 SO 4 ), filtered and concentrated in vacuo . Purifica�on by silica column chromatography using Hexane:EtOAc (1:0 to 1:1 v/v) as the eluent provided the product, which was directly used in the next step. 2,2,2-Trichloroacetonitrile (848 µL, 8.5 mmol) and DBU (51 µL, 0.3 mmol) were added to the intermediate (1.49 g, 1.7 mmol) in DCM (3 mL) with 4 Å molecular sieves at 0°C. A�er 15 min the reac�on mixture was concentrated in vacuo and the obtained crude was directly purified by silica column chromatography using Toluene:EtOAc (1:0 to 8:2 v/v) as the eluent. The obtained compound 26 was directly used in the next step. A mixture of acceptor 28 (100 mg, 0.3 mmol), donor 26 (468 mg, 0.46 mmol) and 4 Å molecular sieves was s�rred in CH 3 CN (5 mL) for 1 h. The mixture was cooled to -30°C and TMSOTf (11 µL, 0.06 mmol) was added. The reac�on mixture was allowed to warm to 15°C over 2 h. The reac�on mixture was O O OBn BnO OBn O HO OBn BnO BnO OMP HO NBnCbz O O OBn BnO OBn O O O BnO BnO Ph O NBnCbz