NAG-thiazoline (NGT) and its derivatives are well-known inhibitors against most b-acetylglucosaminidases (b-GlcNAcases) except for insect and bacterial chitinolytic b-GlcNAcase. Among them, NGT was the only one specifically designed to be an analog of the oxazolinium reaction intermediate based on the substrate-assisted mechanism, an attractive starting point to develop potent inhibitors. It is a major building block for the synthesis of potential inhibitors of transglycosylases involved in bacterial cell wall biosynthesis.