Advances in the synthesis of 7-deazapurine - Pyrrolo[2,3-d]pyrimidine-2 '-deoxyribonucleosides including D- and L-enantiomers, fluoro derivatives and 2 ',3 '-dideoxyribonucleosides

This review reports on the synthesis of 7-deazapurine 2'-deoxyribonucleosides, including beta-D- and beta-L-enantiomers, fluoro derivatives, and 2', 3'-dideoxyribonuclec, sides. It covers the various aspects of convergent nucleoside synthesis. Stereochemically defined alpha-D- and alpha-L-2-deoxy-3,5-di-O-(p-toluoyl)-erythro-pentofuranosyl chlorides as well as 3.5-di-O-benzoyl-2-deoxy-2-fluoro-alpha-D-arabinofuranosyI bromide were employed in nucleobase anion glycosylation. This glycosylation reaction is regioselective for the pyrrole nitrogen and stereoselective for beta-nucleoside formation. 7-Deazapurine 2',3'-dideoxyribonucleosides were synthesized by the same protocol as 2'-deoxyribonucleosides using 2,3dideoxy-5-O-[(1,1-dimethylethyl)dimethylsilyl]-D-glycero-pentofuranosyl chloride., 7-Deazapurine 2',3'-dideoxyribonucleosides were also obtained from 2'-deoxy- or 3'-deoxyribonucleosides by Barton deoxygenation or by elimination of sugar hydroxyl groups. The review discusses the scope and limitations of the glycosylation reaction performed with pyrrolo[2,3-d]pyrimidines as well as on the regioselective halogenation reactions followed by the Sonogashira cross coupling. It reports on the use of 7-deazapurine nucleoside triphosphates in the Sanger dideoxy DNA-sequencing and the application of 7-deazapurine nucleosides as antiviral or anticancer agents.