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Novel acyclic nucleotides and nucleoside 5'-triphosphates imitating 2',3'-dideoxy-2',3'-didehydronucleotides: synthesis and biological properties.

A series of pyrophosphoryl (Z)-(phosphonomethoxy)but-2-enyl derivatives of pyrimidines and purines 9a-d and the corresponding phosphonates 10a-d were synthesized. The prepared compounds contain the phosphonate group as an alpha-phosphate mimic as well as an acyclic residue emulating the sugar moiety in 2',3'-dideoxy-2',3'-didehydronucleoside 5'-triphosphates known as highly potent chain terminators of DNA polymerases. Phosphonates 10a-d were obtained by alternative alkylations of the nucleic bases followed by condensation with ethyl [[(p-tolylsulfonyl)oxy]methyl]phosphonate. Pyrophosphorylation of 10a-d afforded phosphonate diphosphates 9a-d. Their substrate properties were evaluated in cell-free systems containing various DNA polymerases including viral reverse transcriptases. Compounds 9a-d manifested good terminating substrate properties toward HIV-1 and AMV reverse transcriptases. They exhibited high selectivity and were not recognized by human DNA polymerases alpha and epsilon, DNA polymerase beta from rat liver, Escherichia coli DNA polymerase I, and HSV-1 and CMV DNA polymerases. Phosphonates 10b-d displayed no activity in HIV-1-infected MT-4 cells cultures; 10a was moderately effective (ED50 = 9 microM).