Synthesis and Properties of Combinatorial Libraries of Phosphoramidates

We have assembled a set of combinatorial libraries of phosphoramidates for pharmacological evaluation. A range of functionalized and unfunctionalized diols, representing a variety of diversity elements, were converted into their corresponding dimethoxytrityl H-phosphonate derivatives which were coupled to each other to produce H-phosphonate dimers and trimers. The H-phosphonate diesters were converted into phosphoramidates by reaction with a wide range of primary and secondary amines. Very large libraries (theoretically, in excess of one million compounds) possessing five sites of diversity were generated for use in our drug discovery program. Smaller libraries with lower molecular weights were also prepared in which only two monomeric units were coupled together and converted into their phosphoramidate derivatives. Methods for the attachment of both radioactive and nonradioactive labels, including ³²phosphorus, tritium, and fluorescein, have been developed. Representative single sequences were also prepared and their chemical properties studied.