Glycans are macromolecules that contain several classes. Glycans can play an important role in biological activities. Studying the cell surface glycans can provide a very powerful way to understand the fundamental process. Also it could help to regulate expected cell response. Thus it is very necessary to have a method to detect cell- surface glycans efficiently. An efficient method for glycan detection is necessary. Metabolic glycan labeling and chemoenzymatic glycan labeling are most commonly used. Chemoenzymatic glycan labeling is a rapid and sensitive method which also has high specificity. This method can be applied in both vitro and vivo. However the availability of unnatural sugar nucleotides functioned by bioorthogonal groups is the main limitation for chemoenzymatic labeling. In this thesis, UDP-GlcNAc and UDP-GalNAc derivatives were prepared for further chemoenzymatic labeling by using chemoenzymatic synthesis method.