Acyclic Nucleoside and Nucleotide Analogs Derived from 2-Azaadenine

2-azapurine nucleosides: synthesis, properties, and base pairing of oligonucleotides

This review deals with 2-azapurine (imidazo[4,5-d] [1,2,3]triazine) nucleosides and closely related analogs. Different routes are described to yield the desired target compounds, including a sequence of ring-opening and ring-closure reactions performed on purine nucleosides or direct glycosylation of a 2-azapurine nucleobase with a sugar halide. Further, physical and spectroscopic properties of 2-azapurine nucleosides are discussed, including fluorescence, (13)C-NMR data, single-crystal X-ray analyses, and conformation studies on selected compounds; new biological data are presented. The second part of this review is dedicated to oligonucleotides containing 2-azapurines, including building-block (phosphoramidite) preparation and their use in solid-phase oligonucleotide synthesis. Base-pairing properties of 2-azapurine nucleosides as surrogates of canonical constituents of DNA were evaluated.

Acyclic nucleotide analogs derived from 8-azapurines: synthesis and antiviral activity

Reaction of phosphoroorganic synthons with 8-azaadenine, 8-aza-2, 6-diaminopurine, and 8-azaguanine using cesium carbonate yielded regioisomeric 8-azapurine N7-, N8-, and N9-(2-(phosphonomethoxy)alkyl) derivatives. This reaction followed by deprotection afforded isomeric 2-(phosphonomethoxy)ethyl (PME), (S)-(3-hydroxy-2-(phosphonomethoxy)propyl) [(S)-HPMP], (S)-(3-flouro-2-(phosphonomethoxy)propyl) [(S)-FPMP], (S)-(2-(phosphonomethoxy)propyl) [(S)-PMP], and (R)-(2-(phosphonomethoxy)propyl) [(R)-PMP] derivatives. 13C NMR spectra were used for structural assignment of the regioisomers. None of the 8-isomers exhibited any antiviral activity against herpesviruses, Moloney murine sarcoma virus (MSV), and/or HIV. 9-(S)-HPMP-8-azaadenine (23) and PME-8-azaguanine (65) were active against HSV-1, HSV-2, and CMV at 0.2-7 micrograms/mL, VZV at 0.04-0.4 microgram/mL, and MSV (at 0.3-0.6 microgram/mL). PME-8-azaguanine (65) and (R)-PMP-8-azaguanine (71a) protected MT-4 and CEM cells against HIV-1- and HIV-2-induced cytopathicity at a concentration of approximately 2 micrograms/mL.