2‐Nucleos‐5′‐ O ‐yl‐4 H ‐1,3,2‐benzodioxaphos‐phinin‐2‐oxides—A New Concept for Lipophilic, Potential Prodrugs of Biologically Active Nucleoside Monophosphates

A nonenzymatic, hydrolytic tandem reaction selectively releases the 5′‐phosphorylated derivatives of the antiviral active nucleoside analogues ddT and d4T from the nucleoside phosphotriesters 1 and 2 . The hydrolysis of 1 and 2 can be controlled by varying the substituents X . Consequently, compounds of type 1 and 2 should, in principle, be suitable prodrugs of phosphorylated nucleosides.