Patent ID: 7667033

Claim:
A method for synthesizing and purifying a phosphotriester oligonucleotide immobilized on a solid support complex, comprising: a) providing i) a polymer support, and ii) four pools of nucleoside 3′-monomers in solution, said monomers having a nucleoside base and a phosphoramidate group, wherein at least one of said monomers contains 9-fluorenylmethoxycarbonyl as an amino protecting group on the monomer base, and said monomers have an alkyl residue on the phosphate of the phosphoramidite group; b) sequentially contacting said polymer support with a solution of monomers from one or more of said four pools under conditions such that a sequence of monomers is immobilized on said polymer support to generate an oligonucleotide/polymer support complex, wherein said complex comprises at least one monomer containing 9-fluorenylmethoxycarbonyl base protecting group and wherein said solution, after said contacting, comprises unreacted material; c) treating said complex under conditions such that said unreacted material is substantially removed, thereby creating a purified oligonucleotide/polymer support complex, and d) treating said purified oligonucleotide/polymer support complex under conditions whereby said 9-fluorenylmethoxycarbonyl, but not the phosphoramidate alkyl residue, is released.