Xterra ms c18 analytical column

General chemical reagents and solvents were obtained from commercial suppliers. The Bz-protected furanoses (1–4) were prepared according to known procedures [27 (link),29 (link),40 (link),41 (link),42 (link)]. Uridine 5′-phosphoropiperidate (14) was prepared according to a previous report [32 (link)]. All reactions were performed under an atmosphere of inert gas and monitored by thin layer chromatography on plates coated with 0.25 mm silica gel 60 F254. TLC plates were visualized by UV irradiation (254 nm). Flash column chromatography employed silica gel (particle size 32–63 μm). All NMR spectra were obtained with a Bruker AV-400 instrument (Billerica, MA, USA) with chemical shifts reported in parts per million (ppm, δ) and referenced to CDCl₃, MeOH-d₄, or D₂O. The NMR spectra of compounds 5–13 and 15–19 were provided in Supplementary Materials (Figures S1–S42). Low- and high-resolution mass spectra were reported as m/z and obtained with a Bruker amaZon SL and a Bruker Dalton microTOFQ II mass spectrometer, respectively. The HPLC traces of 16–19 were recorded on an Agilent 1260 instrument equipped with a Waters XTerra MS C18 analytical column (4.6 × 150 mm, 5 μm) [flow rate = 1.0 mL/min; linear gradient of 5% to 100% MeOH in TEAB buffer (10 mM, pH 8.0) over 10 min; UV detection at 254 nm] and provided in Supplementary Materials (Figures S43–S46).

The HPLC system (Agilent 1260, Agilent Technologies, Santa Clara, CA, USA) consisted of a XTerra^® MS C₁₈ analytical column (4.6 mm × 150 mm, 5.0 µm, Waters, Dublin, Ireland), a pump (G1311B quaternary pump, Agilent), a UV detector and an automatic injector (G1329B, Agilent). The mobile phrase was methanol–water–phosphoric acid (41:59:0.2, v/v/v) at a flow rate of 1.0 mL/min with linear isocratic elution. The detector operated at 276 nm. The injection volume was 20 μL and the column temperature was 35 °C.