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 β-D- and β-Lenantiomers, fluoro derivatives, and 2',3'-dideoxyribonucleosides. It covers the various aspects of convergent nucleoside synthesis. Stereochemically defined α-D- and α-L-2-deoxy-3,5-di-O-(p-toluoyl)-erythro-pentofuranosyl chlorides as well as 3,5-di-O-benzoyl-2-deoxy-2-fluoro-α-D-arabinofuranosyl bromide were employed in nucleobase anion glycosylation. This glycosylation reaction is regioselective for the pyrrole nitrogen and stereoselective for β-nucleoside formation. 7- Deazapurine 2',3'-dideoxyribonucleosides were synthesized by the same protocol as 2'-deoxyribonucleosides using 2,3- dideoxy-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.