Thiol compounds and the use thereof for the synthesis of modified oligonucleotides

A modified oligonucleotide, having the following formula:

• (AA)-N1— . . . —Nn-1—Nn-(I′)-(M1- . . . -Mm-1-Mm)p-(I′)b
• in which,
• N1, . . . Nn represent, independently of one another, a nucleotide,
• M1, . . . Mm represent, independently of one another, a nucleotide,
• (I′) represents a compound of formula (I′a) or (I′b), where:
• wherein
• W is selected from the group consisting of C1-C6 alkane triyl groups, C6-C12 aryl triyl groups, and C6-C12 aralkane triyl groups, wherein the C1-C6 alkane triyl group is a linear or branched C1-C6 alkane triyl substituted by at least two alkyl groups,
• Z is selected from the group consisting of C1-C6 alkoxy groups, oxygen-containing or nitrogen-containing C3-C6 cycloheteroalkyl groups, C1-C6 NCO-alkyl groups, and C1-C6 CON-alkyl groups,
• Y is selected from the group consisting of linear or branched C1-C6 alkyl groups, C1-C6 aminoalkyl groups, C1-C6 alkoxy groups, C3-C6 cycloalkyl groups, and oxygen-containing or nitrogen-containing C3-C6 cycloheteroalkyl groups,
• X is selected from the group consisting of linear or branched C1-C6 alkyl groups, C1-C6 aminoalkyl groups, C1-C6 alkoxy groups, C3-C6 cycloalkyl groups, and oxygen-containing or nitrogen-containing C3-C6 cycloheteroalkyl groups,
• R is H, and
• R1 is selected from the group consisting of 2-cyanoethyl, R′1R′2R′3SiCH2CH2 groups, and R′1, R′2, R′3, which may be identical or different, and which are selected from the group consisting of linear or branched alkyls comprising from 1 to 12 carbon atoms, and C6-C12 aryls,
• n is an integer comprised between 1 and 100,
• m is an integer comprised between 1 and 100,
• y is an integer comprised between 1 and 12,
• (AA) is a solid support or (Ic)-(I′)y-1,
• wherein when (AA) is a solid support,
• a=y and b=y′, p is 0, and y′ is 0, and
• wherein when (AA) is (Ic)-(I′)y-1,
• a=y′ and b=y″, and y′ is 0, and y″ is 0,
• wherein (Ic) is
• and
• wherein W, Z, X, Y, and R are defined above, D is a protective group of the alcohols that allow orthogonal deprotection with respect to the other groups of compound (I′a), (I′b), or (Ic), J is selected from the group consisting of a single bond and a —CH2—, —CH2CH2—, —CH2OCH2—, or —CH2OPhOCH2— group where Ph is a benzyl, and □ represents a solid support.