A solid-phase method for the introduction of a variety of different side chains into oligoribonucleotides is presented. It is based on a b-D-allofuranosyl phosphoramidite with a bromopentyl-substituent tethered to the 6'-O position. After its incorporation into fully protected, immobilized RNA sequences, the bromine was substituted with a variety of soft nucleophiles which, in some cases, allowed further transformations. After deprotection and detachment, the corresponding functionalized oligoribonucleotides were purified and characterized. Incorporation of such side chains led to a slight lowering of transition temps., but some of them led to a significant enthalpic stabilization of an A-type RNA duplex. [on SciFinder (R)]