Insights into the Soluble PEG-Supported Synthesis of Cytosine-Containing Nucleoside 5′-Mono-, Di-, and Triphosphates

Nucleoside phosphoesters (nucleotides) have crucial roles in a large variety of biological processes including nucleic acid biosynthesis and their corresponding analogues are extensively used as biological tools. Herein, we describe a new and efficient synthetic procedure involving polyethylene glycol (PEG) as soluble support and regioselective mono-, di-, and triphosphorylation steps. Applied to natural and synthetic cytosine containing nucleosides, this methodology allowed the preparation of various phosphorylated forms in high yields and good purity.