Judit E. Šponer

3’,5’‐Cyclic nucleotides play a fundamental role in modern biochemical processes and have been suggested to have played a central role at the origin of terrestrial life. In this work, we suggest that a formamide‐based systems chemistry might account for their availability on the early Earth. In particular, we demonstrate that in a liquid formamide environment at elevated temperatures 3’,5’‐cyclic nucleotides are obtained in good yield and selectivity upon intramolecular cyclization of 5’‐phosphorylated nucleosides in the presence of carbodiimides.