Boranophosphates are salts with an anion consisting of borane (BH3) and phosphite groups. One of the simplest examples is [(CH<sub>3</sub>O)<sub>2</sub>OPBH<sub>3</sub>]−, prepared by base hydrolysis of the adduct of borane and trimethylphosphite.[1]
Boranophosphates have gained attention as structural surrogates of phosphate group in living systems. In some compounds, borane replaces of one of the oxygens of a triphosphate or diphosphate functional group. Phosphorus remains tetrahedral, but the BH3-appended phosphorus center is trivalent. Boranophosphates have been incorporated into nucleotides and studied as potential therapeutic and diagnostic agents.[2] They are one of several covalent modifications of phosphodi- and triesters. The compounds are prepared by attaching the borane to the phosphoramidite stage in the synthesis of nucleosides. The P-BH3 bond is sufficiently robust to survive deprotection methods to allow formation of the triphosphate.[2]
Aside from boranophosphates, other modifications of di- and triphosphates include phosphorothioates and methylphosphonate. They also are chiral at phosphorus.[3]