Direct esterification of phosphates with various halides and its application to synthesis of cAMP alkyl triesters

Esterification of phosphates with various halides, including acid chlorides, phosphoryl trichloride and tin chloride, was achieved in 57–99% isolated yield using silver(I) oxide. The reaction was successfully applied to the preparation of phosphate triesters sensitive to acids and bases. cAMP benzyl esters were also prepared by this method.