Abiotic regioselective phosphorylation of adenosine with borate in formamide

Nearly 40 years ago, Schoffstall and his coworkers used formamide as a solvent to permit the phosphorylation of nucleosides by inorganic phosphate to give nucleoside phosphates, which (due to their thermodynamic instability with respect to hydrolysis) cannot be easily created in water by an analogous phosphorylation (the "water problem" in prebiotic chemistry). More recently, we showed that borate could stabilize certain carbohydrates against degradation (the "asphalt problem"). Here, we combine the two concepts to show that borate can work in formamide to guide the reactivity of nucleosides under conditions where they are phosphorylated. Specifically, reaction of adenosine in formamide with inorganic phosphate and pyrophosphate in the presence of borate gives adenosine-5′-phosphate as the only detectable phosphorylated product, with formylation (as opposed to hydrolysis) being the competing reaction. Key Words: Prebiotic chemistry - Nucleoside phosphates - Phosphorylation - Borate - Formamide. Astrobiology 15, 259-267.