Macrocyclic oligonucleotide labeling reactants and conjugates derived thereof

A labeling reactant of formula (I) suitable for labeling of an oligonucleotide using solid-phase synthesis

• (I)
• wherein,
• -A- is a linker;
• R is —COOR′ or CONHR′ where R′ is an alkyl of 1 to 4 carbon atoms, phenyl or benzyl, which phenyl or benzyl is substituted or unsubstituted;
• m and n are independently 0, 1 or 2;
• Z is a bridge point and is absent or is a radical of a purine base or a pyrimidine base or a 7-deazapurine base or any other modified base suitable for use in the synthesis of modified oligonucleotides, said base being connected to E via either i) a hydrocarbon chain, which is substituted with a protected hydroxyethyl or hydroxymethyl group, or via ii) a furan ring or pyrane ring or any modified furan or pyrane ring, suitable for use in the synthesis of modified oligonucleotides;
• and
• E is either a phosphorylating moiety
• where L is absent or is O or S;
• L′ is H, L′″CH2CH2CN or L′″Ar, where Ar is phenyl or its substituted derivative, where the substituent is nitro or chlorine, and L′″ is O or S;
• L″ is O−, S−, Cl, N(i-Pr)2;
• or
• E is a solid support tethered to Z via a linker arm, which is the same as or different from the linker -A- as defined above.