[Synthesis of Coumarin-oligonucleiotide Conjugates for Application in DNA-encoded Libraries].

Oligonucleotides, including DNA and RNA, can be functionalized by chemical modification based on synthetic organic chemistry. For example, ligand-oligonucleotide conjugates have a wide variety of applications. Conjugates of functional ligands and oligonucleotides have attracted attention in recent years as a drug delivery system (DDS) for improving the efficacy of oligonucleotide therapeutics. In addition, oligonucleotide conjugates with drug candidate compounds as ligands have been applied to drug screening using DNA-encoded libraries (DELs). Against this background, we have focused on the development of practical synthetic methods for ligand-oligonucleotide conjugates. Recently, we have developed a new synthetic method to construct oligonucleotides conjugated with coumarins and dipeptides, which are expected to have bioactivity, for application to DDS research of oligonucleotide therapeutics and drug discovery research using DEL. In this review, we will discuss the details, including how to construct a coumarin scaffold on oligonucleotides based on Knoevenagel condensation.