Abstract: A process of purifying phosphoramidite precursors useful in inter alia synthesis of oligonucleotides comprises dissolving a crude phosphoramidite in a polar phase, adding a basic compound to the polar phase, adding a portion of water to the polar phase, contacting the polar phase with a first apolar phase to extract impurity into the apolar phase, separating the first apolar phase from the polar phase, adding a second aliquot of water to the polar phase, and contacting the polar phase with a second apolar phase, whereby the phosphoramidite partitions into the second apolar phase.

Abstract: The present invention provides nucleoside compounds and certain derivatives thereof which are inhibitors of RNA-dependent RNA viral polymerase. These compounds are inhibitors of RNA-dependent RNA viral replication and are useful for the treatment of RNA-dependent RNA viral infection. They are particularly useful as inhibitors of hepatitis C virus (HCV) NS5B polymerase, as inhibitors of HCV replication, and/or for the treatment of hepatitis C infection. The invention also describes pharmaceutical compositions containing such nucleoside compounds alone or in combination with other agents active against RNA-dependent RNA viral infection, in particular HCV infection. Also disclosed are methods of inhibiting RNA-dependent RNA polymerase, inhibiting RNA-dependent RNA viral replication, and/or treating RNA-dependent RNA viral infection with the nucleoside compounds of the present invention.

Abstract: A scalable process for purification of phosphorodiamidite includes steps of solubilizing a crude phosphorodiamidite in an apolar organic solvent, contacting the non-polar organic solvent with a polar phase comprising a polar organic solvent to remove impurities from the solubilized phosphorodiamidite, and removing the non-polar organic solvent from the phosphorodiamidite.

Abstract: A process for the synthesis in solution phase of a phosphorothioate triester is provided. The process comprises the solution phase coupling of an H-phosphonate with an alcohol in the presence of a coupling agent to form an H-phosphonate diester. The H-phosphonate diester is oxidised in situ with a sulfur transfer agent to produce the phosphorothioate triester. Preferably, the H-phosphonate and alcohol are protected nucleosides or oligonucleotides. Oligonucleotide H-phosphonates which can be used in the formation of phosphorothioate triesters are also provided.

Abstract: A process for the synthesis in solution phase of a phosphorothioate triester is provided. The process comprises the solution phase coupling of an H-phosphonate with an alcohol in the presence of a coupling agent to form an H-phosphonate diester. The H-phosphonate diester is oxidized in situ with a sulfur transfer agent to produce the phosphorothioate triester. Preferably, the H-phosphonate and alcohol are protected nucleosides or oligonucleotides. Oligonucleotide H-phosphonates which can be used in the formation of phosphorothioate triesters are also provided.

Abstract: The present invention provides nucleoside compounds and certain derivatives thereof which are inhibitors of RNA-dependent RNA viral polymerase. These compounds are inhibitors of RNA-dependent RNA viral replication and are useful for the treatment of RNA-dependent RNA viral infection. They are particularly useful as inhibitors of hepatitis C virus (HCV) NS5B polymerase, as inhibitors of HCV replication, and/or for the treatment of hepatitis C infection. The invention also describes pharmaceutical compositions containing such nucleoside compounds alone or in combination with other agents active against RNA-dependent RNA viral infection, in particular HCV infection. Also disclosed are methods of inhibiting RNA-dependent RNA polymerase, inhibiting RNA-dependent RNA viral replication, and/or treating RNA-dependent RNA viral infection with the nucleoside compounds of the present invention.