Versatile solid supports for oligonucleotide synthesis that incorporate urea bridge.

The universal solid support, USIII, representing a new and improved version of commercial USII, as well as 2 '-deoxynucleoside and 2 '-deoxy-2 '-fluoronucleoside bound supports, incorporating a labile phenoxyacetyl fragment, was synthesized by an aminomethyl polystyrene carbamoylation with corresponding azides in the presence of aqueous triethylammonium bicarbonate. All three solid phases incorporate a stable urea tether, thus bridging the polymer and functional linker. These new matrices proved to be potent solid phases for the synthesis of DNA, RNA, or modified oligonucleotides as well as randomized mixed 2 '-ribo/2 '-deoxy-2 '-fluoro-RNA libraries and/or DNA libraries, randomized with trinucleotides (codons).