Process for terminal substituting of a polynucleotide

Claim 1

A process for substituting a reactive hydrophobic organic moiety for hydrogen at the 5'--O-- position of the terminal nucleotide of a support bound oligonucleotide, the process comprising the step of combining the support bound oligonucleotide with a reactive hydrophobic organic halide in an organic, substantially anhydrous solvent in the presence of a reagent and a tertiary amine base under substantially anhydrous conditions, wherein: (a) the reactive hydrophobic organic halide consists of the reactive hydrophobic organic moiety and a halogen moiety, the reactive hydrophobic moiety being selected from the group consisting of trityl and pixyl moieties; (b) the 5'--O-- position of the terminal nucleotide becomes attached to the saturated, tertiary carbon of the reactive hydrophobic organic moiety; (c) the reagent is present in an amount sufficient to attach to substantially all of the halogen moiety of the reactive hydrophobic organic halide, and the reagent is selected from the group consisting of tetraalkyl ammonium salts, the reagent having a cation moiety consisting of a tetraalkylammonium ion wherein the alkyl groups contain from 1 to about 20 carbon atoms and an anion moiety; and (d) the cation moiety of the reagent is more electropositive than the reactive hydrophobic organic moiety of the reactive hydrophobic organic halide so that the cation moiety of the reagent is capable of attracting the halogen moiety of the reactive hydrophobic organic halide.