Synthesis of Prodrug‐Type Oligonucleotides Modified With a Galactosylated Self‐Immolative Linker Cleavable by β‐Galactosidase

This protocol describes procedures for the preparation of a modified thymidine conjugated with galactose via a self-immolative linker at the O4-position, and the synthesis of β-galactosidase-responsive prodrug-type oligodeoxynucleotides (ONs) containing these modified thymidines. These prodrug-ONs are designed to be activated in response to β-galactosidase, enabling targeted activation in specific cells or tissues and potentially contributing to the reduction of adverse effects. © 2025 Wiley Periodicals LLC. Basic Protocol 1: Preparation of O4-modified thymidine phosphoramidite 7 Basic Protocol 2: Preparation of O4-modified thymidine phosphoramidite 15 Support Protocol 1: Preparation of triazolyl thymidine derivative 1 Support Protocol 2: Preparation of benzyl alcohol derivative 2 Basic Protocol 3: Preparation of β-galactosidase-responsive ODNs 1 to 5.