Expanding the Genetic Alphabet: Non-Epimerizing Nucleoside with the <i>py</i>DDA Hydrogen-Bonding Pattern

Abstract

6-Amino-3-(2'-deoxy-beta-D-ribofuranosyl)-5-nitro-1H-pyridin-2-one (4), a C-glycoside exhibiting the nonstandard pyDDA hydrogen-bonding pattern, was synthesized via Heck coupling. The nitro group greatly enhances the stability of the nucleoside toward acid-catalyzed epimerization without leading to significant deprotonation of the heterocycle at physiological pH. These results make nucleoside 4 a promising candidate for an expanded genetic alphabet.