Scheme 3. Synthesis of Bis-hetero-aminooxy-modified 2′-OMe-uridine Building Blocks.

For 16a–18a, R₁ is hexadecyl, and R₂ is CH₃; for 16b–18b, R₁ is dilinoleyl, and R₂ is CH₃; for 16c–18c, R₁ is cyclopropyl-dilinoleyl, and R₂ is CH₃; for 16d–18d, R₁ is hexadecyl, and R₂ is methyl-16-oxohexadecanoate; for 16e–18e, R₁ is protected tri-GalNAc, and R₂ is hexadecyl.