Abstract
Convergent syntheses of the 9‐(3‐X‐2,3‐dideoxy‐2‐fluoro‐β‐D‐ribofuranosyl)adenines 5 (X=N~3~) and 7 (X=NH~2~), as well as of their respective α‐anomers 6 and 8, are described, using methyl 2‐azido‐5‐O‐benzoyl‐2,3‐dideoxy‐2‐fluoro‐β‐D‐ribofuranoside (4) as glycosylating agent. Methyl 5‐O‐benzoyl‐2,3‐dideoxy‐2,3‐difluoro‐β‐D‐ribofuranoside (12) was prepared starting from two precursors, and coupled with silylated N^6^‐benzoyladenine to afford, after deprotection, 2′,3′‐dideoxy‐2′,3′‐difluoroadenosine (13). Condensation of 1‐O‐acetyl‐3,5‐di‐O‐benzoyl‐2‐deoxy‐2‐fluoro‐β‐D‐ribofuranose (14) with silylated N^2^‐palmitoylguanine gave, after chromatographic separation and deacylation, the N^7^‐β‐anomer 17 as the main product, along with 2′‐deoxy‐2′‐fluoroguanosine (15) and its N^9^‐α‐anomer 16 in a ratio of ca. 42 : 24 : 10. An in‐depth conformational analysis of a number of 2,3‐dideoxy‐2‐fluoro‐3‐X‐D‐ribofuranosides (X=F, N~3~, NH~2~, H) as well as of purine and pyrimidine 2‐deoxy‐2‐fluoro‐D‐ribofuranosyl nucleosides was performed using the PSEUROT (version 6.3) software in combination with NMR studies.