摘要 |
A novel approach for combining the ease of cleavage of carboxylic acid linker arms with the single phosphoramidite coupling chemistry of the universal supports useful in oligonucleotide synthesis. There is disclosed a new class of phosphoramidite reagents, linker phosphoramidites, which contain a bifunctional linker arm with a protected nucleoside linked through a 3'-ester bond on one end and a reactive phosphoramidite group or other phosphate precursor group on the other end-see <cross-reference target="DRAWINGS">FIGS. 2 and 3</cross-reference>. The phosphoramidite group on the linker phosphoramidite may be activated under the same conditions and has similar reactivity as conventional nucleoside-3'-phosphoramidite reagents lacking the intermediate linker arm. The 3'-ester linkage contained within the linker phosphoramidite has similar properties to the linkages on prederivatized supports. The ester linkage is stable to all subsequent synthesis steps, but upon treatment with a cleavage reagent, such as ammonium hydroxide, the ester linkage is hydrolyzed. This releases the oligonucleotide product with the desired 3'-hydroxyl terminus and leaves the phosphate portion of the reagent attached to the support, which is subsequently discarded.
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