Pyrroles substituted by oligonucleotides

A substituted pyrrole, characterized in that it corresponds to general formula (IV):

• in which
• R2 is an amine-protecting group chosen from monomethoxytrityl, dimethoxytrityl, tosyl, triisopropylsilyl, tert-butoxycarbonyl, 9-fluorenyloxycarbonyl, benzyloxycarbonyl and acetyl,
• R3 is a phosphorus-comprising group capable of reacting with a free hydroxyl group, chosen from a phosphotriester, H-phosphonate or phosphoramidite group,
• X represents a spacer arm chosen from —(CH2)n—O—, —(CH2)p—O—[(CH2)2—O]q—, —(CH2)r—CO—NR′—(CH2)r′—O—, —(CH2)r—NCH3—(CH2)r′—O—, —(CH2)r—CO—NR′—[(CH2)2—O]s—, —(CH2)r—NCH3—[(CH2)2—O]s—,
• R′ represents —H or —CH3,
• n is an integer between 1 and 5,
• p is an integer between 1 and 2,
• q is an integer between 1 and 4,
• r is an integer between 1 and 3,
• r′ is an integer between 1 and 3,
• s is an integer between 1 and 3,
• n, p, q, r, r′ and s are identical or different,
• the pyrrole ring is substituted in the 2-, 3-, 4- or 5-position.

A method for preparing a pyrrole substituted with an oligonucleotide of general formula (I)

• in which R1, X and Y are as described above,
• characterized in that it comprises the following steps:
• a) the cycles for synthesizing an oligonucleotide are carried out,
• b) in the final cycle for synthesizing said oligonucleotide, a substituted pyrrole of general formula (IV)
• in which R2, R3 and X are as defined above, is substituted at the final nucleotide in the 5′ position or in the 3′ position of said oligonucleotide;
• c) said protective group R2 is cleaved.