The present invention relates to processes and reagents for
oligonucleotide synthesis and purification. One aspect of the present invention relates to compounds useful for activating phosphoramidites in
oligonucleotide synthesis. Another aspect of the present invention relates to a method of preparing oligonucleotides via the
phosphoramidite method using an activator of the invention. Another aspect of the present invention relates to
sulfur-transfer agents. In a preferred embodiment, the
sulfur-
transfer agent is a 3-amino-1,2,4-dithiazolidine-5-one. Another aspect of the present invention relates to a method of preparing a phosphorothioate by treating a phosphite with a
sulfur-transfer
reagent of the invention. In a preferred embodiment, the sulfur-
transfer agent is a 3-amino-1,2,4-dithiazolidine-5-one. Another aspect of the present invention relates to compounds that scavenge
acrylonitrile produced during the deprotection of
phosphate groups bearing ethylnitrile protecting groups. In a preferred embodiment, the
acrylonitrile scavenger is a
polymer-bound
thiol. Another aspect of the present invention relates to agents used to oxidize a phosphite to a
phosphate. In a preferred embodiment, the
oxidizing agent is
sodium chlorite, chloroamine, or
pyridine-N-
oxide. Another aspect of the present invention relates to methods of purifying an
oligonucleotide by annealing a first single-stranded oligonucleotide and second single-stranded oligonucleotide to form a double-stranded oligonucleotide; and subjecting the double-stranded oligonucleotide to chromatographic purification. In a preferred embodiment, the chromatographic purification is high-performance liquid
chromatography.