A solution of pre-dried 5-(3-hydroxy-1-propynyl)-2′-deoxyuridine Robins, M. J. et al., (1983) (565 mg, 2 mmol) in 40 mL of anhydrous THF under argon was treated with 4-nitrophenol (696 g, 5 mmol), triphenylphosphine (787 mg, 3 mmol), and diisopropyl azodicarboxylate (590 L, 3 mmol), and the reaction mixture heated at 60° C. until the solution was clear, and then 1 h longer. The mixture was allowed to cool to 23° C. and then it was evaporated onto SiO2 and purified by chromatography using MeOH/CH2Cl2 as eluent to afford 107 mg (13%) of the desired ether product: mp 112-118° C. 1H NMR ((CD3)2SO) δ 11.65 (s, exchanges with D2O, 1, NH), 8.29 (s, 1, H6), 8.24 (d, J=9.3 Hz, 2, m-ArH), 7.23 (d, J=9.3 Hz, 2, oArH), 6.09 (pseudo-t, 1, H1′), 5.17 (s, 2, propargyl-CH2), 4.22 (m, 1, H3′), 3.80 (m, 1, H4), 3.59 (m, 2, 5′-CH2), 2.13 (pseudo-t, 2, 2′-CH2). Low-resolution mass spectrum (DCI-NH3) on per-trimethylsilyated material, m/z 547 [M(TMS)2H+], 565 [M(TMS)2NH+], 620 [M(TMS)3H+]n.
