N-donor Base Adducts of P2O5 as Diphosphorylation Reagents

Donor-stabilized adducts of the P2O5 molecule are reported. The compounds are of the general formula P2O5D2, where D = DABCO, pyridine, and DBU. The DABCO adduct was initially prepared from trimetaphosphate but could be prepared more conveniently from phosphorus pentoxide. The reactions leading to P2O5D2 (D = DABCO) also generate P3O8D3 and both adducts were structurally characterized. The pyridine adduct P2O5D2 (D = pyridine) was most easily prepared in good purity and yield and thus its diphosphorylation chemistry was developed. Its reaction with protic nucleophiles MeOH and HNEt2 yield salts of [P2O7Me2]2-, a dimethyl ester of pyrophosphate, and [P2O5(NEt2)2]2-, a phosphoramidate derivative which was structurally characterized. Diphosphorylation of adenosine monophosphate yielded a cyclic intermediate which could be opened by nucleophiles including water to provide ATP, diethylamine to provide γ-diethylamino-ATP, and uridine monophosphate to provide adenosine uridine tetraphosphate. Adenosine diphosphate was diphosphorylated to provide, following hydrolytic ring opening, adenosine tetraphosphate.