Syntheses of some 5'-C-phosphonomethyl-, 2'-C- and 3'-C-branched nucleoside analogues as potential anti-HIV agents are described. Synthesis of the various nucleoside analogues is based either on the construction of a suitably protected sugar moiety that can be glycosylated with different nucleoside bases by the Vorbrüggen procedure, or on the use of a novel alcohol transposition in the carbohydrate moiety of different 2'-C- or 3'-C-methylene nucleoside analogues, using the reagent system chlorodiphenylphosphine-iodine-imidazole. All target compounds were tested for anti-HIV activity. Of these, only 2',3'-dideoxy-2'-Chydroxymethylcytidine and l-(3,5-dideoxy-ß-D-cryrAro-hexofuranosyl)thymine demonstrated moderate and weak anti-HIV activities, respectively.