and the crude product was purified by a silica gel chromatography column using CH2Cl2 and CH3OH (100:1-30:1, v/v) as an eluent.
L1a. Nankin wax (0.32 g, 75.2%) from 5 (0.1 g, 0.17 mmol). 1H NMR (400 MHz, CDCl3): 1.49 (s, 6H, NapCH3×2), 2.32-2.42 (m, 6H, COCH2×3), 2.51-2.64 (brs, 6H, N-CH2×3), 2.75-3.04 (brs, 16H, Asp-ßCH2), 3.46-3.64 (m, 4H, CONCH2×2), 3.69-3.78 (brs, 2H, NapCOCH×2), 3.85 (s, 6H, NapOCH3×2), 3.96-4.17 (m,6H, CH2-O×2+ Gly-CH2), 4.56-4.98(m, 8H, Asp-aCH), 5.03 (s, 20H, ph-CH2), 7.04-7.71 (m, 62H, Nap-phH + phH). ESI MS (m/z): calcd. for 2623.8 obsd. 2624.5([M+H]+).
L1b. Yellow oil (0.41 g, 79.2%) from 5 (0.1 g, 0.17 mmol). 1H NMR (400 MHz, CDCl3): 1.54 (s, 6H, NapCH3×2), 2.36-2.49 (m, 6H, COCH2×3), 2.55-2.66 (brs, 6H, N-CH2×3), 2.81-2.99 (brs, 20H, Asp-ßCH2), 3.48-3.68 (m, 4H, CONCH2×2), 3.72-3.76 (m, 2H, NapCOCH×2), 3.92 (s, 6H, NapOCH3×2), 4.01-4.20 (m,6H, CH2-O×2+ Gly-CH2), 4.60-4.99 (m, 10H, Asp-aCH), 5.13 (s, 24H, ph-CH2), 7.15-7.71 (m, 72H, Nap-phH + phH). ESI MS (m/z): calcd. for 3034.2 obsd. 1518.2([M+2H]+ /2).
L1c. Yellow oil (0.48 g, 82.1%) from 5 (0.1 g, 0.17 mmol). 1H NMR (400 MHz, CDCl3): 1.47 (s, 6H, NapCH3×2), 2.31-2.46 (m, 6H, COCH2×3), 2.58-2.64 (m, 6H, N-CH2×3), 2.77-2.98 (brs, 24H, Asp-ßCH2), 3.43-3.66 (m, 4H, CONCH2×2), 3.69-3.78 (brs, 2H, NapCOCH×2), 3.85 (s, 6H, NapOCH3×2), 3.96-4.17 (m,6H, CH2-O×2+ Gly-CH2), 4.46-4.97 (m, 8H, Asp-aCH), 5.11 (s, 28H, ph-CH2), 7.14-7.71 (m, 82H, Nap-phH + phH). ESI MS (m/z): calcd. for 3444.6 obsd. 1723.5 ([M+2H]+ /2).
General Procedure for the Synthesis of the dendrimer T1
A mixture of dendrimer L1 (1.0 equiv) and 10% Pd/C (0.1 equiv) in methanol was stirred at room temperature under a H2 atmosphere. After 24 h the mixture passed through a membrane filter to remove the catalyst, then evaporated under reduced pressure. After concentration, the residue was triturated with pure ethyl ether to afford T1 as white powders.
T1a. 0.12 g, 95% from L1a 0.2 g. 1H NMR (400 MHz, D2O): 1.58 (s, 6H, NapCH3×2), 2.20-2.44 (m, 6H, COCH2×3), 2.58-2.64 (m, 6H, N-CH2×3), 2.71-2.86 (brs, 16H, Asp-ßCH2), 3.48-3.55 (m, 4H, CONCH2×2), 3.69-3.71 (m, 2H, NapCOCH×2), 3.78 (s, 6H, NapOCH3×2), 4.09-4.18 (m,6H, CH2-O×2+Gly-CH2), 4.67-4.86 (m, 8H, Asp-aCH), 7.14-7.77 (m, 12H, Nap-phH), ESI MS (m/z): calcd. for 1708.6 obsd. 1730.2 ([M+Na]+ ). Anal. calcd. for C74H89N11O36: C, 52.02, H, 5.25, N,9.02. found: C, 52.49, H, 4.97, N, 9.22.
T1b. 0.12 g, 91% from L1b 0.2 g. 1H NMR (400 MHz, D2O): 1.53 (s, 6H, NapCH3×2), 2.15-2.39 (m, 6H, COCH2×3), 2.47-2.62 (m, 6H, N-CH2×3), 2.77-3.04 (brs, 20H, Asp-ßCH2), 3.42-3.49 (m, 4H, CONCH2×2), 3.69-3.72 (m, 2H, NapCOCH×2), 3.80 (s, 6H, NapOCH3×2), 4.02-4.21 (m,6H, CH2-O×2+Gly-CH2), 4.71-4.93 (m, 10H, Asp-aCH), 7.05-7.72 (m, 12H, Nap-phH), ESI MS (m/z): calcd. for 1938.7 obsd. 1939.2 ([M+H]+ ). Anal. calcd. for C82H99N13O42: C, 50.80, H, 5.15, N,9.39. found: C, 50.54, H, 5.63, N, 9.20.
T1c. 0.11 g, 89% from L1c 0.2 g. 1H NMR (400 MHz, D2O): 1.49 (s, 6H, NapCH3×2), 2.21-2.33 (m, 6H, COCH2×3), 2.52-2.67 (m, 6H, N-CH2×3), 2.71-2.96 (brs, 24H, Asp-ßCH2), 3.40-3.51 (m, 4H, CONCH2×2), 3.70-3.72 (m, 2H, NapCOCH×2), 3.84 (s, 6H, NapOCH3×2), 4.01-4.17 (m,6H,
