Acyclic N 9 adenine nucleosides substituted at C-1′ position were prepared by the Mitsunobu reaction of 1-tert-butyldimethylsilyl-4-pivaloylbutan-1, 2, 4-triol (5) with adenine. Pivaloyl hydroxyl was modified to the phosphonomethoxy derivatives, and the tert- butyldimethylsilyl hydroxyl was converted to methoxy, azido, amino, fluoro, and α- hydroxyethyl and was eliminated to give vinyl. The resulting phosphonic acids were ...