Synthesis of N4-acetylated 3-methylcytidine phosphoramidites for RNA solid-phase synthesis

Abstract

The growing interest in 3-methylcytidine (m3C) originates from the recent discoveries of m3C modified tRNAs in humans as well as its intensively debated occurrence in mRNA. Moreover, m3C formation can be catalyzed by RNA without the assistance of proteins as has been demonstrated for a naturally occurring riboswitch fold using the methylated form of its cognate ligand as cofactor. Additionally, new RNA sequencing methods have been developed to detect this modification in transcriptome-wide manner. For all these reasons, an increasing demand for synthetic m3C containing oligoribonucleotides is emerging. Their chemical synthesis relies on RNA solid-phase synthesis using phosphoramidite building blocks. Here, we describe a facile synthetic path towards N4-acetylated 2′-O-TBDMS- and 2′-O-TOM m3C phosphoramidites to provide an optimal toolbox for solid-phase synthesis of m3C containing RNA.Graphical abstract