Glycine anhydride (also known as diglycine cyclic anhydride) is a specialty chemical primarily used in peptide synthesis as an activated building block. It acts as an acylating agent to facilitate peptide bond formation, enabling the creation of dipeptides and more complex peptide structures while minimizing side reactions. This compound serves as a key intermediate in the production of pharmaceuticals, particularly in synthesizing active pharmaceutical ingredients (APIs). It is also employed in the development of biodegradable polyanhydride polymers for drug delivery and environmentally friendly materials. Additionally, in organic synthesis, it is used to prepare heterocyclic compounds such as diketopiperazines, which are significant in medicinal chemistry and materials science.