Synthesis and Potent Anti-HCMV Activity of 2',5',5'-trifluoro-3'-hydroxy-apiosyl Nucleoside Phosphonic Acid Analogues

As antiviral nucleosides containing a fluorine atom at 2'-position are endowed with increased stabilization of glycosyl bond, it was of interest to investigate the influence of three fluorine atoms at 2'- and 5'-positions of apiosyl nucleoside phosphonate analogues. Various pyrimidine and purine 2',5',5'-trifluoro-3'-hydroxy-apiose nucleoside phosphonic acid analogues were synthesized from 1,3-dihydroxyacetone. Electrophilic fluorination of lactone was performed using N-fluorodibenzenesulfonimide. Difluorophosphonation was performed by direct displacement of triflate intermediate with diethyl(lithiodifluoromethyl) phosphonate to give the corresponding (α,α-difluoroalkyl) phosphonate. Condensation successfully proceeded from a glycosyl donor with persilylated bases to yield nucleoside phosphonate analogues. Deprotection of diethyl phosphonates provided the final phosphonic acid sodium salts. The synthesized nucleoside analogues were subjected to antiviral screening against various viruses.