Modular assembly of purine-like bisphosphonates as inhibitors of HIV-1 reverse transcriptase.

Bisphosphonates can mimic the pyrophosphate leaving group of the nucleotidyl transfer reaction and effectively inhibit RNA/DNA polymerases. In a search of HIV-1 reverse transcriptase (RT) inhibitors, a new chemotype of nonhydrolyzable purine diphosphate mimic was synthesized. A modular synthetic protocol was developed, utilizing 2-amino-6-(methylthio)-4-(trimethylsilyl)nicotinonitrile as the key synthon in the preparation of highly substituted 2-aminonicotinonitriles. These building blocks were subsequently elaborated to the pyrido[2,3-d]pyrimidine bisphosphonates (PYPY-BPs). Biochemical screening identified analogs of PYPY-BPs that inhibit HIV-1 RT-catalyzed DNA synthesis.