5-formylcytosine specific chemical labeling method and related applications

A method for specific chemical labeling of 5-formylcytosine or a 1-substituted derivative thereof, comprising the step of reacting an active methylene compound containing a side-chain active group R1—CH2—R2 with the 5-formylcytosine or a 1-substituted derivative thereof, wherein a dehydration condensation reaction occurs between the active methylene compound containing a side-chain active group and a 5-formyl group of cytosine in the 5-formylcytosine or a 1-substituted derivative thereof, and at the same time an intramolecular reaction occurs between the side-chain active group of the active methylene compound and a 4-amino group of cytosine in the 5-formylcytosine or a 1-substituted derivative thereof to implement ring closing, as shown in the equation below:

• wherein, R represents hydrogen, hydrocarbyl, hydrocarbyl with —OH, —NH2, —CHO and/or —COOH, ribosyl or deoxyribosyl, 5′- or 3′-phosphate-modified ribosyl or deoxyribosyl, or structures excluding the 5-formylcytosine from ribonucleic acid or deoxyribonucleic acid binding to 1-position of the 5-formylcytosine via glucosidic bond;
• the hydrocarbyl is C1-C30 linear or branched alkyl, C1-C30 linear or branched alkenyl, or C1-C30 linear or branched alkynyl;
• R1 is an electrondrawing group selected from the group consisting of cyano, nitro, formyl, carbonyl compound
• and
• R2 is an electrondrawing group selected from the group consisting of cyano, formyl, carbonyl compound
• and
• R3 is an unsubstituted C1-C30 linear or branched alkyl, alkenyl or alkynyl, or a C1-C30 linear or branched alkyl, alkenyl or alkynyl substituted with —OH, —NH2, —CHO, —COOH, azido and/or biotin;
• and
• R1 and R2 are independent from each other or forming a ring directly by bonding with each other or forming a ring indirectly by bonding via an atom C, N or O.