Compound 1018899-04-1, commonly referred to as Thalidomide-O-amido-PEG2-C2-NH2 or Thalidomide-PEG2-amine, is a synthetic chemical probe designed for targeted protein degradation research. It is a bifunctional molecule consisting of a thalidomide derivative (a well-known ligand for the Cereblon E3 ubiquitin ligase) connected to a primary amine group via a short polyethylene glycol (PEG2) linker. This primary amine serves as a versatile chemical handle for further conjugation. This compound is a key building block in the development of Proteolysis-Targeting Chimeras (PROTACs) and other molecular glues. The thalidomide moiety recruits the Cereblon E3 ligase complex, while the terminal amine allows for the attachment of a ligand targeting a protein of interest (POI). This proximity induces ubiquitination and subsequent proteasomal degradation of the POI. It is widely used in chemical biology and drug discovery to study protein function and validate novel therapeutic targets. As a research-grade chemical, it is primarily utilized in academic and industrial laboratories for probe synthesis and proof-of-concept studies. Handling requires standard laboratory safety precautions for organic compounds.