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PADS/NMP for sulfurization of oligonucleotides

IP.com Disclosure Number: IPCOM000114760D
Publication Date: 2005-Mar-29
Document File: 1 page(s) / 30K

Publishing Venue

The IP.com Prior Art Database

Abstract

Many of the synthetic antisense oligonucleotides (ASO's) in clinical development are phosphorothioates. The most common method of manufacture of such ASO's is by supported solid-phase synthesis by means of phosphoramidite chemistry. Addition of each nucleotide residue typically involves a synthetic cycle of 4 reactions: detritylation, coupling, sulfurization and capping. In the sulfurization step, the newly created triphosphite group [P(III) oxidation level ] is converted to a phosphorothioate group [P(V) oxidation level] by treatment with a sulfur-transfer reagent.

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PADS/NMP for sulfurization of oligonucleotides

Many of the synthetic antisense oligonucleotides (ASO’s) in clinical development are phosphorothioates.

The most common method of manufacture of such ASO’s is by supported solid-phase synthesis by means of phosphoramidite chemistry.

Addition of each nucleotide residue typically involves a synthetic cycle of 4 reactions: detritylation, coupling, sulfurization and capping. In the sulfurization step, the newly created triphosphite group [P(III) oxidation level ] is converted to a phosphorothioate group [P(V) oxidation level] by treatment with a sulfur-transfer reagent.

Several sulphur-transfer reagents are reported for this reaction. These include 3H-1,2-benzodithiol-3-one 1,1-dioxide (also known as Beaucage reagent; Iyer et al., J. Org. Chem, 1990, 55, 4693) phenylacetyl disulfide (usually abbreviated as PADS; NL8902521; US6114519; Cheruvallath et al., Organic Process Research & Development, 2000, 4, 199) and 3-amino-1,2,4-dithiazole-5-thione (Tang et al., Organic Process Research & Development, 2000, 4, 194).

For operation of the sulfurization process, a solution of the sulfur-transfer reagent in an organic solvent, also containing a pyridine or substituted pyridine base, is passed through a column containing the solid-supported oligonucleotide. In order to obtain acceptable chemical yields and purities at gram scale or a multi-kilo scale, a number of organic solvents are suitable for this purpose. Acetonitrile, toluene and 1...