Abstract: A process for the synthesis of phosphorothioate oligonucleotides is provided which comprises assembling an oligonucleotide bound to a solid support in the presence of acetonitrile; prior to cleaving the oligonucleotide from the solid support removing the acetonitrile; and cleaving the oligonucleotide from the solid support. The process is particularly suited to the large scale synthesis of nucleotides. The acetonitrile may be removed from the solid support by one or both of drying and by washing with solvents. Preferred washing solvents comprise trialkylamines.

Abstract: A process for the synthesis of phosphorothioate oligonucleotides is provided which comprises assembling an oligonucleotide bound to a solid support in the presence of acetonitrile; prior to cleaving the oligonucleotide from the solid support removing the acetonitrile; and cleaving the oligonucleotide from the solid support. The process is particularly suited to the large scale synthesis of nucleotides.

Abstract: A process for the synthesis of phosphorothioate oligonucleotides is provided which comprises assembling an oligonucleotide bound to a solid support in the presence of acetonitrile; prior to cleaving the oligonucleotide from the solid support removing the acetonitrile; and cleaving the oligonucleotide from the solid support. The process is particularly suited to the large scale synthesis of nucleotides. The acetonitrile may be removed from the solid support by one or both of drying and by washing with solvents. Preferred washing solvents comprise trialkylamines.

Abstract: An oligonucleotide analogue having 10 to 200 natural and/or synthetic nucleoside units, linked by internucleoside linkages, at least one of the internucleoside linkages being of formula where the indicated methylene group is attached to a 3′ carbon atom of a nucleoside, the indicated oxygen atom is attached to a 5′-carbon atom of an adjacent nucleside, R1 is hydrogen, hydroxy, O—, thiol, S—, —NH2 or a group of formula R1a, —OR1a, —SR1a, —NHR1b, or —NR1bR1c wherein R1a is an unsubstituted or substituted C1 to C10 alkyl, C2 to C10 alkenyl, C3 to C8 cycloalkyl, C6 to C10 aryl or C7 to C13 aralkyl group; and R1b and R1c are each independently an unsubstituted or substituted C1 to C10 alkyl, C2 to C10 alkenyl, C3 to C8 cycloalkyl, C6 to C10 aryl or C7 to C13 aralkyl group or R1b and R1c together with the nitrogen atom to which they are attached denote a five- or six-membered heterocyclic ring, and X is oxygen or sulfur.

Abstract: A process for the synthesis of phosphorothioate oligonucleotides is provided which comprises assembling an oligonucleotide bound to a solid support in the presence of acetonitrile; prior to cleaving the oligonucleotide from the solid support removing the acetonitrile; and cleaving the oligonucleotide from the solid support. The process is particularly suited to the large scale synthesis of nucleotides.

Abstract: A compound of formula (I) wherein B1 is a radical of a nucleoside base, R1 is hydrogen or a hydroxy-protecting group, R2 is hydrogen, hydroxy or a 2′-nucleoside-modifying atom or group, R3 is an unsubstituted or substituted C1 to C10 alkyl, C2 to C10 alkenyl, C4 to C10 cycloalkylalkyl, C6 to C10 aryl or C7 to C13 aralkyl group, and Z is halogen or a group of formula (II) where R4 and R5 are each independently an unsubstituted or substituted C1 to C10 alkyl, C2 to C10 alkenyl, C4 to C10 cycloalkylalkyl, C6 to C10 aryl or C7 to C13 aralkyl group, or R4 is said group and R5 is hydrogen or R4 and R5 together with the nitrogen atom to which they are attached denote a five- to thirteen-membered heterocyclic ring, or Z is a group of formula (III): Nuc-O—, where Nuc is the residue of a natural or synthetic nucleoside or oligonucleotide after removal of a 5′-hydroxyl group therefrom attached through a 5′-methylene thereof to the indicated oxygen atom.