Title compds. consisting of ribo-, arabino-, xylo-, or lyxo-pyranoses in place of the usual ribo-furanose, were prepd. and used in solid-phase synthesis to construct (b-D-ribo)-(4'->2')-H-GGGCGGGC-H(I). Thus, 1,2,3,4-tetra-O-benzoyl-a/b-D-ribo-pyranose was substituted at the 1-position with a series of protected nucleoside bases, and the sugar manipulated through a series of steps to give either the 4'-O-dimethoxytrityl-3'-O-benzoyl-2'-O-(allyloxy)(diisopropyl-amino)phosphine compds. suitable for solid-phase synthesis of oligonucleotides, or 2'-O-CO(CH2)5CO2H compds. suitable for attachment to amine-resins to form the initial base of a growing chain. A key step in this synthesis was the simultaneous protection of 3'- and 4'-O by reaction with an aldehyde, ketone, acetal, or ketal protecting group to form cyclic acetals. These intermediates were then used in the construction of I. [on SciFinder (R)]