Fmoc-L-Asn(beta-D-GlcNAc(Ac)3)-OH, also known as Fmoc-Asn(Ac3AcNH-beta-Glc)-OH, is a chemical compound used in the synthesis of silicon-fluoride acceptor (SiFA) derivatized octreotate derivatives. SiFA-octreotate analogues, which serve as tumor imaging agents, are valuable tools for positron emission tomography (PET) research.