Ethylene Glycol → 2-(3-{2-[2-(2-{2-Azidoethoxy}ethoxy)ethoxy]ethoxy}-4,5-dimethoxyphenyl)-1,3-dioxolane

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A mixture of 4.95 g (12.91 mmol) 3-{2-[2-(2-{2-azidoethoxy}ethoxy)ethoxy]ethoxy}-4,5-dimethoxybenzaidehyde 8, 5 ml (5.57 g, 90 mmol) ethylene glycol and 200 mg (1.0 mmol) p-toluene sulfonic acid monohydrate was refluxed in 120 ml of toluene for 8 hrs using a Dean-Stark trap. After cooling to room temperature the rection mixture was poured into 200 ml of diluted sodium bicarbonate solution, washed with water and brine and dried over magnesium sulfate. After removal of the solvent the residue was purified by silica gel column chromatography (cyclohexane/ethyl acetate 1/1), giving 4.43 g (10.8 mmol, 80%) of the product as a clear oil. 1H-NMR (CDCl3) δ=6.73 (dd, 2H, J=5.0 Hz, J=1.8 Hz), 5.72 (s, 1H), 4.19 (m, 2H), 4.11 (m, 2H), 4.03 (m, 2H), 3.87 (s, 3H), 3.84 (s, 3H), 3.76-3.71 (m, 4H), 3.70-3.64 (m, 8H), 3.37 (m, 2H) ppm. 13C-NMR δ=153.3, 152.4, 139.2, 133.1, 105.4, 103.6, 103.4, 70.7, 70.6, 70.5 (2 peaks), 69.9, 69.6, 68.7, 65.1, 60.6, 56.0, 50.6 ppm. MS: m/z=427 [M]+. Anal. calcd for C19H29N3O8: C, 53.39, H, 6.84, N, 9.83. Found C, 52.30, H, 6.89, N, 9.72.

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