Abstract
<jats:p>Nonenzymatic primer extension is thought to have enabled genetic replication prior to the emergence of enzymatic replicases. Chemically modified nucleic acids have proven effective in overcoming key limitations of nonenzymatic RNA replication, including low reaction rates and poor fidelity. Specifically, activated 3′-amino-2′,3′-dideoxynucleotides polymerize substantially faster than their RNA counterparts, but undergo intramolecular cyclization over time. Here we show that these cyclic phosphoramidates are not dead-end products, but dynamic intermediates connecting nucleotide activation, phosphorus recycling, and template-directed polymerization. Chemoselective triphosphorylation, pH-modulated phosphorus transfer, and imidazole-catalyzed ring opening enable reversible phosphoroimidazolide formation; resulting in monomers that can directly participate in in situ nonenzymatic chemical copying. These results establish a sustainable chemical network linking nucleosides to template-directed synthesis of N3′→P5′ phosphoramidate DNA, offering new insights into sustainable prebiotic (re)activation chemistry.</jats:p>