3.1. Chemistry

General Information: All chemicals were reagent grade and were used without further purification. Tetrahydrofuran was dried by heating under reflux over sodium wire in the presence of benzophenone as an indicator while dimethylformamide was dried by activated 3 Å molecular sieves. When necessary, the compounds were dried in vacuum over CaCl₂. Reactions were monitored by Merck KGaA TLC silica gel plates (0.25 mm)( Kenilworth, NJ, USA) and visualized by 254 nm UV light, or by spraying with H₂SO₄-Ce(SO₄)₂. The derivatives 8 [67], 12a [45], 12b [65], and 12c [66] have been synthesized according to literature procedures. Proton ¹H and carbon ¹³C nuclear magnetic resonance (NMR) experiments were recorded at 298K except when specified on Bruker Avance III HD 400 MHz, 500 MHz, or 600 MHz spectrometer (Billerica, MA, USA). Chemical shifts are reported relative to the residual solvent peak. A COSY spectrum was taken using a relaxation delay of 2 s with 30 scans and 170 increments of 2048 points each. HSQC spectra were performed with gradient selection, sensitivity enhancement, and phase sensitive mode using Echo/Antiecho-TPPI procedure. Optical rotations were measured at 589 nm (sodium lamp) and 20 °C on either a Perkin-Elmer 341 polarimeter (Waltham, MA, USA) or an Anton Paar MCP 200 polarimeter(Graz, Austria) with a path length of 1 dm. Infrared (IR) spectra were recorded neat on a Perkin–Elmer Spectrum Two FT-IR spectrometer. High-resolution (HRMS) electrospray ionization-time-of-flight (ESI-TOF) mass spectra were recorded on a Bruker micrOTOF^® mass spectrometer.

Synthesis of derivatives 10 and 11: Cs₂CO₃ (1.25 equiv for each OH group) as added to a suspension of the appropriate calix[8]arene derivative 8 or 9 (1.0 g) in acetone (100 mL). The reaction mixture was stirred at reflux for 2 h. Then the system was cooled at room temperature and propargyl bromide (2.50 equiv for each OH group) was added. The reaction mixture was then stirred at reflux for 20 h, then it was cooled at room temperature and the solvent was removed under reduced pressure. An aqueous 1N solution of HCl (150 mL) was added to the reaction mixture and the suspension was stirred for 15 min. The aqueous phase was extracted and washed with CH₂Cl₂ (3 × 70 mL) and the organic phases were collected, dried over Na₂SO₄, filtered, and the solvent was removed under reduced pressure. The crude product was dissolved in a small amount of CH₂Cl₂ and then MeOH was added. The precipitated was filtered, affording the pure product as a white solid.

Compound 10: (76% yield); ESI(+) MS: m/z = 1603.1 [M + H]⁺, 1624.9 [M + Na]⁺; ¹H NMR (400 MHz, CDCl₃, 298 K): δ 1.11 (s, tBu, 72H), 2.30 (br t, 8H), 4.10 (s, 16H), 4.21 (d, J = 2.1 Hz, 16H), 6.95 (s, 16H) ppm; ¹³C NMR (100 MHz, CDCl₃, 298K): δ 31.2, 31.5, 34.4, 60.9, 75.4, 79.7, 126.3, 133.4, 146.9, 153.1 ppm; Anal. calcd for C₁₁₂H₁₂₈O₈: C, 83.96; H, 8.05; found C, 83.01; H, 8.16. Compound 11: (57% yield); ESI(+) MS: m/z = 1628.7 [M+H]⁺, 1647.9 [M+Na]⁺, 1667.9 [M+K]⁺; ¹H NMR (600 MHz, CDCl₃, 298K): δ 0.55 (s, 18H), 1.17 (s, 36H), 1.38 (s, 18H), 2.46 (br t, 4H), 2.56 (br t, 2H), 3.56 (s, 4H), 4.10 (s, 8H), 4.21 (s, 8H), 4.57 (s, 8H), 4.74 (s, 4H), 5.95 (s, 4H), 6.70 (s, 4H), 6.91 (s, 4H), 7.24 (br d, J = 2.2 Hz, 4H), 7.27 (s, 4H) ppm; ¹³C NMR (150 MHz, CDCl₃, 298K): δ 31.0, 31.1, 31.6, 31.8, 34.0, 34.5, 60.6, 61.4, 75.2, 75.6, 80.0, 80.4, 124.6, 124.7, 126.3, 127.2, 128.3, 129.0, 132.4, 133.1, 133.6, 134.9, 136.43, 146.2, 146.4, 146.5, 151.5, 152.6, 154.4 ppm. Anal. calcd for C₁₁₄H₁₃₀O₈: C, 84.09; H, 8.05; found C, 83.10; H, 8.14.

General procedure for the CuAAC with 12a and 12b: The calix[8]arene derivative 10 or 11 (10–15 mg) and the appropriate azide-armed DNJ iminosugar 12a or 12b (1.2 equiv for each alkyne unit) were dissolved in DMF (1.0 mL) in an ACE pressure tube. Then, a solution of Cu₂SO₄.5H₂O (0.1 equiv. for each alkyne unit) and sodium ascorbate (0.2 equiv. for each alkyne unit) in water (0.25 mL) was added. The reaction mixture was heated under microwave irradiation for 20–30 min, using a CEM Corporation Discover LabMate system with the temperature controller. The mixture was concentrated, and traces of copper salts were removed by filtration through a short pad of silica gel eluting with CH₃CN/AcOEt/NH₄OH (9:1:1). The filtrate was concentrated and then purified by flash chromatography on silica gel.

Compound 13a: (AcOEt-AcOEt:MeOH 98:2, 51% yield; MS (ESI) m/z calcd for C₂₇₂H₃₈₄N₃₂Na₂O₇₂ [M + 2Na]²⁺ 2648.3577; found 2648.3351; [α]_D²⁸ = +3.5 (c = 1, CHCl₃); ¹H NMR (300 MHz, CDCl₃, 298K): δ 0.89 (s, 72H), 1.25 (br, 32H), 1.39 (br, 16H), 1.77 (br, 16H), 2.00–2.04 (m, 96H), 2.30 (t, J = 10.6 Hz, 8H), 2.53 (m, 8H), 2.61 (m, 8H), 2.70 (m, 8H), 3.16 (dd, J₁ = 11.6 Hz, J₂ = 4.9 Hz, 8H), 4.06 (s, 16H), 4.14 (br, 16H), 4.18 (overlapped, 16H), 4.79 (s, 16H), 4.92 (m, 8H), 5.03 (overlapped, 16H), 6.80 (s, 16H), 7.79 (s, 8H) ppm; ¹³C NMR (75 MHz, CDCl₃, 298K): δ 20.9, 20.9, 21.1, 24.8, 26.6, 26.9, 30.2, 30.5, 31.4, 34.2, 50.2, 51.9, 53.1, 59.6, 61.6, 66.6, 69.6, 69.7, 74.9, 123.9, 126.1, 133.3, 144.1, 146.6, 152.7, 169.9, 170.2, 170.5, 171.0 ppm. Anal. calcd for C₂₇₂H₃₈₄N₃₂O₇₂: C, 62.18; H, 7.37; found C, 62.07; H, 7.48.

Compound 13b: (AcOEt:Petroleum Ether, 8:2, 52% yield); MS (ESI) m/z calcd for C₂₉₆H₄₃₂N₃₂Na₂O₇₂ [M + 2Na]²⁺ 2816.5455; found 2816.5469; [α]_D²⁷ = +5.0 (c = 1, CHCl₃); ¹H NMR (600 MHz, CDCl₃, 298K): δ 0.90 (s, 72H), 1.24 (overlapped, 80H), 1.39 (br, 16H), 1.76 (br, 16H), 2.00–2.06 (overlapped, 96H), 2.32 (t, J = 10.9 Hz, 8H), 2.55 (m, 8H), 2.62 (br d, J = 9.2 Hz, 8H), 2.70 (m, 8H), 3.17 (dd, J₁ = 11.4 Hz, J₂ = 5.1 Hz, 8H), 4.06 (s, 16H), 4.14 (br, 16H), 4.18 (br, 16H), 4.79 (s, 16H), 4.95 (m, 8H), 5.0–5.07 (overlapped, H3+H4, 16H), 6.80 (s, 16H), 7.78 (s, 8H) ppm; ¹³C NMR (150 MHz, CDCl₃, 298 K): 20.9, 20.9, 21.1, 21.1, 24.8, 26.8, 27.5, 29.3, 29.7, 29.9, 30.6, 31.4, 34.2, 50.3, 52.1, 53.2, 59.7, 61.6, 66.6, 69.7, 69.7, 74.9, 123.9, 126.1, 133.3, 144.2, 146.6, 152.7, 170.0, 170.2, 170.6, 171.1 ppm. Anal. calcd for C₂₉₆H₄₃₂N₃₂O₇₂: C, 63.59; H, 7.79; found C, 63.50; H, 7.86.

Compound 14a: (AcOEt/Petroleum Ether 9:1-AcOEt, 51% yield); MS (ESI) m/z calcd for C₂₃₄H₃₂₂N₂₄Na₂O₅₆ [M + 2Na]²⁺ 2205.1435; found 2205.1329; [α]_D³⁰ = +4.0 (c = 1, CHCl₃); ¹H NMR (600 MHz, CDCl₃, 298K): δ 0.40 (s, 18H), 0.95–1.54 (overlapped, 44H), 1.17 (s, 36H), 1.41 (s, 18H), 1.86 (t, J = 7.2 Hz, 12H), 1.98–2.06 (overlapped, 72H), 2.25–2.30 (overlapped, 6H), 2.42–2.62 (overlapped, 14H), 2.69–2.74 (m, 4H), 3.10 (dd, J₁ = 11.5 Hz, J₂ = 5.2 Hz, 4H), 3.18 (dd, J₁ = 11.5 Hz, J₂ = 5.2 Hz, 2H), 3.32 (s, 4H), 3.44–3.48 (overlapped, 4H), 3.53 (m, 4H), 3.86–3.97 (overlapped, 8H), 4.07–4.17 (overlapped, 12H), 4.33 (t, J = 7.8 Hz, 4H), 4.36–4.40 (overlapped, 4H), 4.79 (d, J = 13.2 Hz, 4H), 4.89–4.96 (overlapped, 6H), 4.97–5.08 (overlapped, 12H), 5.82 (s, 4H), 6.58 (s, 2H), 6.61 (s, 2H), 6.95 (s, 2H), 6.98 (s, 2H), 7.22–7.28 (overlapped, 6H), 7.77 (s, 4H) ppm; ¹³C NMR (150 MHz, CDCl₃, 298 K): δ 20.9, 21.0, 21.1, 24.4, 25.0, 26.5, 26.7, 26.8, 29.9, 30.3, 30.4, 30.6, 31.1, 31.6, 31.9, 33.9, 34.5, 34.5, 50.1, 50.4, 51.7, 51.9, 51.9, 53.1, 53.2, 59.4, 59.7, 61.5, 61.6, 61.9, 66.2, 67.0, 69.6, 69.7, 74.8, 75.0, 123.1, 123.3, 123.4, 124.0, 124.3, 127.3, 128.7, 129.2, 132.7, 133.4, 134.6, 134.7, 136.6, 144.0, 144.34, 146.5, 146.7, 152.4, 153.8, 169.9, 170.1, 170.3, 170.6, 171.1 ppm. Anal. calcd for C₂₃₄H₃₂₂N₂₄O₅₆: C, 64.36; H, 7.43; found C, 64.26; H, 7.51.

Compound 14b: (AcOEt/Petroleum Ether 72:28–AcOEt, 37% yield); MS (ESI) m/z calcd for C₂₅₂H₃₅₈N₂₄Na₂O₅₆ [M + 2Na]²⁺ 2331.2844; found 2331.7650; [α]_D³¹ = +7.5 (c = 1, CHCl₃); ¹H NMR (600 MHz, CDCl₃, 298K): δ 0.41 (s, 18H), 1.05–1.30 (overlapped, 60H), 1.18 (s, 36H), 1.39 (s, 18H), 1.54 (br, 8H), 1.86 (br, 4H), 2.00–2.02 (overlapped, 72H), 2.29–2.34 (overlapped, 6H), 2.52–2.57 (overlapped, 6H), 2.61–2.64 (overlapped, 6H), 2.66–2.74 (overlapped, 6H), 3.14–3.20 (overlapped, 6H), 3.34 (s, H18, 4H), 3.43 (d, J = 14.4 Hz, 4H), 3.51 (d, J = 16.8 Hz, 4H), 3.89–3.99 (m, 8H), 4.10–4.17 (overlapped, 12H), 4.33 (t, J = 7.3 Hz, 4H), 4.39 (d, J = 16.6 Hz, 4H), 4.78 (d, J = 14.2 Hz, 4H), 4.92–4.97 (overlapped, 6H), 5.00–5.08 (overlapped, 24H), 5.84 (s, ArH, 4H), 6.60 (s, 4H), 6.96 (s, 4H), 7.24 (s, 4H), 7,26 (overlapped, 8H), 7.78 (s, 2H) ppm; ¹³C NMR (150 MHz, CDCl₃, 298 K): δ 20.9, 21.0, 21.1, 21.2, 21.3, 22.9, 24.6, 24.9, 26.7, 26.7, 27.4, 27.5, 29.1, 29.2, 29.6, 29.7, 29.9, 30.1, 30.4, 30.6, 30.8, 31.1, 31.6, 31.8, 32.1, 33.9, 34.5, 50.3, 50.6, 52.0, 52.2, 53.2, 53.2, 59.7, 59.7, 60.6, 61.5, 61.7, 66.2, 67.1, 69.7, 69.7, 74.9, 75.0, 123.1,123.5, 124.0, 124.3, 127.3, 128.6, 129.2, 131.9, 132.8, 133.4, 134.7, 136.7, 144.2, 144.4, 145.9, 146.4, 146.5, 151.3, 152.4, 153.9, 169.9, 170.2, 170.2, 170.6, 171.1, 171.4 ppm. Anal. calcd for C₂₅₂H₃₅₈N₂₄O₅₆: C, 65.52; H, 7.81; found C, 65.43; H, 7.90.

General procedure for deacetylation of clusters 13a,b and 14a,b: The acetylated compound (10–15 mg) was dissolved in dry methanol (0.3–0.5 mL), and then NaOMe (0.45 equiv for each acetyl group) was added. The reaction mixture was stirred at room temperature for 6 h under nitrogen atmosphere. Methanol and water were added to dissolve the white precipitate. Dowex 50WX8-200 resin was added until pH=6–7 was reached. Then the solution was filtered and concentrated to give the pure compound.

Compound 6a: 67% yield; MS (ESI) m/z calcd for C₂₀₈H₃₂₀Na₂O₄₀ [M + 2Na]²⁺ 1676.1887; found 1976.1792; [α]_D³³= +13.0 (c = 0.067, MeOH); ¹H NMR (600 MHz, MeOD, 298 K): δ 0.96 (s, 72H), 1.26–1.29 (overlapped, 32H), 1.50 (br, 16H), 1.73 (br, 16H), 2.31 (overlapped, 8H), 2.34 (overlapped, 8H), 2.68 (m, 8H), 2.88 (m, 8H), 3.08 (dd, J₁ = 11.7 Hz, J₂ = 5.04 Hz, 8H), 3.19 (t, J = 9 Hz, 8H), 3.40 (t, J = 9.2 Hz, 8H), 3.53 (m, 8H), 3.87 (br, 16H), 4.09 (s, 16H), 4.19 (br, 16H), 4.80 (br s, 16H), 6.89 (s, 16H), 7.96 (s, 8H), 8.51 (s, OH) ppm; ¹³C NMR (150 MHz, MeOD, 298 K): δ 25.1, 27.0, 27.5, 27.9, 28.2, 30.4, 30.5, 30.9, 31.3, 32.1, 33.2, 35.2, 36.6, 51.3, 53.9, 57.2, 58.7, 67.5, 70.2, 71.4, 80.1, 125.9, 131.0, 134.6, 145.2, 147.9, 154.1 ppm. Anal. calcd for C₂₀₈H₃₂₀N₃₂O₄₀: C, 63.91; H, 8.25; found C, 64.01; H, 8.16.

Compound 6b: 82% yield; MS (ESI) m/z calcd for C₂₃₂H₃₆₈N₃₂Na₂O₄₀ [M + 2Na]²⁺ 2144.3765; found 2144.3665; [α]_D²⁷ = −4.0 (c = 0.24, MeOH); ¹H NMR (600 MHz, MeOD, 313 K): δ 0.95 (s, 72H), 1.25 (overlapped, 80H), 1.57 (br, 16H), 1.76 (br, 16H), 2.46–2.49 (overlapped, 16H), 2.80 (m, 8H), 3.00 (m, 8H), 3.17 (dd, J₁ = 11.3 Hz, J₂ = 4.56 Hz, 8H), 3.23 (t, J = 9.1 Hz, 8H), 3.45 (t, J = 9.3 Hz, 8H), 3.57 (m, 8H), 3.87 (dd, J₁ = 11.9 Hz, J₂ = 2.5 Hz, 8H), 3.94 (dd, J₁ = 12.1 Hz, J₂ = 2.0 Hz, 8H), 4.07 (s, 16H), 4.21 (br, 16H), 4.81 (s, 16H), 6.88 (s, 16H), 7.96 (s, 8H), 8.43 (br s, 32H) ppm; ¹³C NMR (600 MHz, MeOD, 313 K): δ 25.0, 27.6, 28.2, 30.0, 30.3, 30.4, 30.5, 30.6, 30.7, 30.8, 31.2, 31.3, 31.9, 33.2, 35.1, 36.5, 49.8, 51.2, 53.9, 54.7, 56.6, 58.0, 67.4, 67.5, 69.6, 70.9, 79.6, 125.8, 127.2, 134.6, 145.2, 147.8, 154.0 ppm. Anal. calcd for C₂₃₂H₃₆₈N₃₂O₄₀: C, 65.63; H, 8.74; found C, 65.54; H, 8.84.

Compound 7a: 67% yield; MS (ESI) m/z calcd for C₁₈₆H₂₇₄N₂₄Na₂O₃₂ [M + 2Na]²⁺ 1701.0168; found 1701.0117; [α]_D²⁹ = −2.0 (c = 1, MeOH); ¹H NMR (600 MHz, MeOD, 298 K): δ 0.44 (s, 18H), 1.23 (s, 36H), 1.24–1.49 (overlapped, 44H), 1.48 (s, 18H), 1.81 (t, J = 7.2 Hz, 4H), 2.40–2.52 (overlapped, 12H), 2.68–2.75 (overlapped, 6H), 2.87–2.97 (overlapped, 6H), 3.11–3.16 (overlapped, 6H), 3.20–3.24 (overlapped, 6H), 3.36 (s, 4H), 3.40–3.46 (overlapped, 6H), 3.52–3.58 (overlapped, 6H), 3.60–3.65 (overlapped, 8H), 3.82–3.94 (overlapped, 20H), 4.37–4.42 (overlapped, 8H), 4.89–4.96 (overlapped, 8H), 5.15 (br s, 8H), 5.86 (s, 4H), 6.67 (s, 4H), 7.05 (d, J = 7.2 Hz, 4H), 7.36 (s, 4H), 7.39 (s, 4H), 7.42 (s, 4H), 8.28 (s, 2H), 8.44 (br s, OH) ppm; ¹³C NMR (150 MHz, MeOD, 298 K): δ 23.7, 24.5, 24.5, 24.7, 27.2, 27.27, 27.6, 30.3,30.5, 30.6, 30.7, 31.0, 31.1, 31.2, 31.9, 32.0, 32.2, 33.1, 34.9, 35.3, 35.6, 51.3, 51.3, 53.7, 53.7, 56.4, 56.5, 56.7, 57.5, 58.1, 66.7, 67.3, 67.4, 67.5, 69.4, 69.5, 69.7, 70.6, 71.0, 76.2, 79.5, 79.6, 79.7, 125.0, 126.0, 126.1, 128.7, 129.8, 130.3, 133.2, 133.2, 134.1, 134.9, 135.4, 137.7, 145.1, 145.1, 145.3, 147.1, 148.0, 148.1, 152.57, 153.5, 153.5, 154.8 ppm. Anal. calcd for C₁₈₆H₂₇₄N₂₄O₃₂: C, 66.52; H, 8.22; found C, 66.62; H, 8.12.

Compound 7b: 80% yield; MS (ESI) m/z calcd for C₂₀₄H₃₁₀N₂₄Na₂O₃₂ [M + 2Na]²⁺ 1827.1576; found 1827.1540; [α]_D²⁹ = −4.0 (c = 1, MeOH); ¹H NMR (600 MHz, MeOD, 298 K): δ 0.45 (s, 18H), 1.03–1.29 (overlapped, 60H), 1.22 (s, 36H), 1.45 (s, 18H), 1.48–1.56 (overlapped, 20H), 1.83 (m, 4H), 2.35–2.45 (overlapped, 12H), 2.71–2.78 (overlapped, 6H), 2.90–2.96 (overlapped, 6H), 3.09–3.14 (overlapped, 6H), 3.38 (s, 4H), 3.40–3.45 (overlapped, 6H), 3.50–3.56 (overlapped, 14H), 3.85–3.97 (overlapped, 20H), 4.36–4.42 (overlapped, 8H), 4.87–4.92 (overlapped, 8H), 5.11 (d, J = 12 Hz, 4H), 5.16 (s, 4H), 5.89 (s, 4H), 6.67 (s, 4H), 7.02 (s, 4H), 7.35 (s, 4H), 7.36 (s, 4H), 7.40 (s, 4H), 8.25 (s, 2H), 8.50 (br s, OH) ppm; ¹³C NMR (150 MHz, MeOD, 298 K): δ 23.7, 25.0, 25.2, 27.4, 27.5, 28.3, 29.8, 29.9, 30.2, 30.4, 30.7, 31.1, 31.3, 31.4, 31.7, 31.9, 32.0, 32.2, 34.8, 35.3, 35.3, 51.4, 53.9, 54.8, 56.9, 57.0, 58.3, 58.6, 66.8, 67.4, 67.5, 69.9, 70.0, 71.2, 71.3, 79.8, 79.9, 125.1, 125.3, 126.0, 128.7, 129.7, 130.3, 133.3, 134.1, 134.8, 135.6, 137.9, 145.2, 147.1, 147.8, 147.9, 152.5, 153.6, 154.9 ppm. Anal. calcd for C₂₀₄H₃₁₀N₂₄O₃₂: C, 67.86; H, 8.65; found C, 67.97; H, 8.56.

General Procedure for the CuAAC Reaction with trivalent dendron 12c: The calix[8]arene derivative 10 or 11 (10–15 mg) and the derivative 12c (1.2 equiv. for each alkyne unit) were dissolved in DMF (1.0 mL) in an ACE pressure tube. Then, a solution of Cu₂SO₄.5H₂O (0.1 equiv. for each alkyne unit) and sodium ascorbate (0.2 equiv. for each alkyne unit) in water (0.25 mL) was added. The resulting suspension was heated under microwave irradiation at 80 °C for 30 min, then water (10 mL) was added, and the aqueous phase was extracted with EtOAc (3 × 12 mL). The organic phases were combined, dried with Na₂SO₄, and concentrated in vacuo. Traces of copper salts were removed by filtration through a short pad of silica gel eluting with CH₃CN/H₂O/NH₄OH (15:0.5:0.5), and the residue was then purified by flash chromatography (SiO₂; CH₂Cl₂/MeOH, 99:1 to 95:5) to give the desired iminosugar.

Compound 13c: 66% yield; [α]_D²⁰ = +3.5 (c = 1, MeOH); ¹H NMR (CDCl₃, 400 MHz): δ 7.85 (br s, 8H), 7.57 (s, 24H), 6.8 (br s, 16H), 5.10–4.99 (m, 48H), 4.98–4.91 (m, 24H), 4.81 (br s, 53H), 4.51 (s, 48H), 4.41 (br s, 10H), 4.33–4.27 (t, J = 7.4 Hz, 48H), 4.14 (s, 48H), 4.03 (br s, 92H), 3.52–3.36 (m, 96H), 3.21–3.15 (dd, J₁ = 11.4, J₂ = 5.0 Hz, 24H), 2.76–2.66 (m, 24H), 2.65–2.60 (m, 24H), 2.59–2.50 (m, 24H), 2.35–2.28 (dd, J₁ = 10.9, J₂=10.5 Hz, 24H), 2.06 (s, 72H), 2.02–1.99 (overlapped, 216H), 1.90–1.84 (m, 48H,), 1.46–1.16 (288H), 0.97–0.72 (m, 72H) ppm; ¹³C-NMR (CDCl₃, 100 MHz): δ 171.0, 170.4, 170.1, 169.9, 145.3, 122.6, 74.9, 70.4–69.8, 69.7, 69.6, 69.4, 65.2, 61.6, 59.7, 53.1, 51.9, 50.4, 50.1, 45.5, 31.3, 30.5, 29.6, 29.2, 27.3, 26.7, 24.9, 21.0, 21.0, 20.9, 20.8 ppm; IR (neat) 1745 cm⁻¹; MS (ESI, deconvoluted): m/z calcd for C₈₀₈H₁₂₄₉N₁₂₀O₂₄₀ [M + 10H]¹⁰⁺ 1648.4740; found 1648.4710.

Compound 14c: 48% yield; [α]_D²⁰ = + 4.5 (c = 1, MeOH); ¹H NMR (CDCl₃, 400 MHz, 298K): δ 8.11–7.59 (m, 57H), 7.61–7.50 (m, 18H), 7.38–7.16 (m, 8H), 6.96–6.58 (m, 4H), 6.58 (s, 4H), 5.89–5.73 (m, 4H), 5.16–4.99 (m, 48H), 4.99–4.91 (m, 18H), 4.89–4.63 (m, 9H), 4.61–4.44 (m, 42H), 4.36–4.22 (m, 42H), 4.14 (s, 36H), 3.91–3.80 (m, 4H), 3.78–3.63 (m, 8H), 3.54–3.31 (m, 72H), 3.21–3.15 (dd, J₁ = 11.5 and J₂ =4.9 Hz, 18H), 2.76–2.66 (m, 18H), 265–2.60 (m, 18H), 2.59–2.49 (m, 18H), 2.35–2.28 (t, J = 10Hz, 18H), 2.09–2.04 (s, 54H), 2.03–2.00 (s, 108H), 2.01–1.98 (s, 54H), 1.93–1.79 (m, 36H), 1.49–1.10 (m, 270H), 0.37 (s, 18H) ppm; ¹³C NMR (CDCl₃, 75 MHz, 298 K): δ 170.9, 170.4, 170.1, 169.8, 162.6, 145.42, 145.37, 144.2, 122.62, 122.53, 74.9, 69.8, 69.6, 69.5, 68.1, 65.2, 61.7, 59.8, 53.1, 52.0, 51.9, 50.4, 50.4, 45.6, 45.5, 36.6, 34.4, 34.4, 31.8, 31.6, 31.5, 31.1, 30.5, 29.6, 29.2, 27.4, 26.7, 25.8, 25.1, 25.0, 20.97, 20.94, 20.85, 20.80 ppm; MS (ESI, deconvoluted) m/z calcd for C₆₃₆H₉₇₈N₉₀O₁₈₂ [M + 14H]¹⁴⁺ 913.8864; found 913.9960.

General procedure for the deacetylation reaction of 13c and 14c: Amberlite resin IRA 400 (6n g/mmol of substrate; n = number of acetate groups) was added to a solution of acetylated iminosugar in a mixture of MeOH/H₂O (1:1), and the resulting solution was stirred for 4 h by using a rotary evaporator at atmospheric pressure. The resin was then removed by filtration and washed with methanol and water. Solvents were evaporated under reduced pressure to give the desired deprotected iminosugar.

Compound 6c: 89% yield; [α]_D²⁰ =−2.5 (c = 1, MeOH); ¹H NMR (MeOD, 400 MHz, 298K): δ 8.22–7.99 (br s, 8H), 7.97–7.82 (s, 24H), 7.19–6.59 (br s, 16H), 4.57–4.42 (m, 64H), 4.41–4.28 (m, 48H), 3.84 (s, 48H), 3.54–3.32 (overlapped, 64H), 3.20–3.07 (m, 24H,), 3.01–2.94 (dd, J₁ = 11.9, J₂ = 5.5 Hz, 24H), 2.83–2.71 (m, 24H), 2.62–2.50 (m, 24H), 2.20–2.12 (dd, J₁ = 11.9, J₂ = 11.5 Hz, 24H), 2.12–2.07 (m, 24H), 1.94–1.79 (m, 48H), 1.55–1.38 (m, 48H), 1.39–1.17 (m, 240H), 0.99–0.79 (m, 72H) ppm; ¹³C-NMR (MeOD, 100 MHz, 298K) δ 146.2, 124.9, 80.6, 72.1, 70.8, 67.4, 65.5, 59.6, 57.8, 53.8, 51.4, 32.1, 31.4, 30.6, 30.1, 28.6, 27.6, 25.3 ppm; IR (neat) 3356 (broad strong OH) cm⁻¹; MS (ESI, deconvoluted) m/z calcd for C₆₁₆H₁₀₅₈N₁₂₀O₁₄₄ [M + 10H]¹⁰⁺ 1244.9054; found 1244.9090.

Compound 7c: 96% yield; [α]_D²⁰ =−5.0 (c = 1, MeOH/H₂O 1:1); ¹H NMR (MeOD, 500 MHz, 298K): δ 8.33 (s, 2H), 7.99–7.85 (several s, 18H), 7.69 (several s, 4H), 7.41–7.20 (m, 8H), 6.96 (s, 4H), 6.80–6.55 (m, 4H), 5.95–5.81 (m, 4H), 5.21–4.98 (m, 12H), 4.64 (m, 4H), 4.54–4.25 (m, 88H), 3.84 (m, 40H), 3.73–3.58 (m, 8H), 3.54–3.22 (m, 120H), 3.13 (t, J = 9.0 Hz, 18H), 2.97 (dd, J = 11.2 and 5.1 Hz, 18H), 2.82–2.72 (m, 18H), 2.61–2.51 (m, 18H), 2.16 (dd, J = 11.1 and 10.0 Hz, 18H), 2.10 (m, 18H), 1.90–1.77 (m, 36H), 1.51–1.19 (m, 270H), 0.43 (s, 18H) ppm; ¹³C-NMR (MeOD, 125 MHz, 20480 scans) δ 155.0, 153.5, 152.4, 147.8, 147.5, 146.8, 146.1, 145.3, 145.1, 137.9, 135.8, 135.0, 134.2, 133.6, 133.3, 132.4, 130.4, 129.86, 129.8, 129.5, 128.8, 126.9, 126.8, 125.9, 125.2, 124.9, 80.6, 76.2, 72.0, 70.8, 71.3, 71.2, 70.3, 70.11, 69.99, 69.08, 67.3, 65.51, 65.46, 59.5, 57.8, 53.8, 51.3, 46.53, 46.50, 35.4, 35.3, 34.9, 32.3, 32.2, 32.0, 31.4, 30.6, 30.1, 28.6, 27.5, 25.2) ppm. IR (neat) 3338 (broad strong OH) cm⁻¹. MS (ESI) m/z calcd for C₄₉₂H₈₃₀N₉₀O₁₁₀ [M + 10H]¹⁰⁺ 976.6409; found 976.6068.