This chemical is a specialized phosphoramidite building block for the synthesis of oligonucleotides, specifically incorporating 5-methyl-2'-deoxycytidine (5-mdC) into DNA sequences. It is widely used in molecular biology and genetic research, particularly for automated solid-phase synthesis of customized oligonucleotides. The 5-methyl modification mimics epigenetic methylation of cytosine, enabling studies of DNA methylation patterns in applications such as PCR, gene editing, sequencing, and epigenetics research. Protective groups include DMT at the 5'-O position for selective deprotection, N4-acetyl on the cytidine base to prevent side reactions, and CE phosphoramidite at the 3' position for efficient coupling. This compound is essential for producing high-quality, site-specifically methylated DNA strands for diagnostic, therapeutic, and research purposes in biotechnology and pharmaceuticals.