Synthesis and anti-HIV-1 evaluation of phosphonates which mimic the 5'-monophosphate of 4'-branched 2',3'-didehydro-2',3'-dideoxy nucleosides.

Synthesis of the 4'-ethynyl and 4'-cyano phosphonates 8-11, which mimic the 5'-monophosphate of 4'-branched 2',3'-didehydro-2',3'-dideoxy nucleosides, was investigated by employing the 3',4'-unsaturated nucleosides (13 and 28) as the starting material. The synthesis was initiated by the electrophilic addition of NIS/(EtO)(2)P(O)CH(2)OH to these unsaturated nucleosides. After introduction of the 2',3'-double bond, the 4'-hydroxylmethyl group of the resulting adducts was transformed into the ethynyl or cyano group. While the 4'-cyano phosphonates 9 and 11 were not sufficiently stable to be isolated, the 4'-ethynyl counterparts (8 and 10) were obtained as their mono-ammonium salts. The adenine derivative 8 showed almost comparable anti-HIV-1 activity to that of d4T.

Synthesis and antiviral evaluation of 4'-alkoxy analogues of 9-(beta-D-xylofuranosyl)adenine.

BACKGROUND: Motivated by the reported biological activity of 9-(beta-D-xylofuranosyl)adenine (xylo-A), the synthesis of its 4'-alkoxy analogues was carried out. METHODS: The starting material 9-(3-deoxy-beta-D-glycero-pento-3-enofuranosyl)adenine (1) was prepared from adenosine. Compound 1 was converted to the 2',5'-bis-O-(tert-butyldimethylsilyl) derivative (2) and then to the N(6)-pivaloyl derivative (3). When 3 was reacted with meta-chloroperbenzoic acid in the presence of a series of alcohols, the beta-D-isomer of the respective 4'-alkoxy derivative was obtained exclusively in high yield. Deprotection of these products led to the isolation of the desired 4'alkoxy analogues (8a-l) of xylo-A. RESULTS: Antiviral evaluation revealed that none of these analogues showed inhibitory activity against a wide variety of DNA and RNA viruses. CONCLUSIONS: We assume that conformational difference of the sugar moiety of 8a-l from that of xylo-A could be attributable to their inactivity.