Synthesis of Janus Bases for Targeting C‑G and U-U Pairs of CUG-RNA Repeats Associated with Myotonic Dystrophy Type 1

We report the synthesis of bifacial Janus bases E and K, along with their corresponding γ peptide nucleic acid monomers, designed to recognize C-G and U-U pairs within CUG-RNA repeats implicated in Myotonic Dystrophy Type 1. This study establishes the foundation for a fully programmable system of 16 Janus bases capable of recognizing all possible RNA base-pairsboth canonical and noncanonicalallowing precise manipulation of RNA structure and function. Importantly, beyond targeting CUG-repeats, this system holds a potential promise for addressing other triplet repeat expansions linked to over 35 neuromuscular and neurodegenerative disorders, thereby opening up new avenues for therapeutic intervention.