Maleimide is a chemical compound with the formula H2C2(CO)2NH. This is an unsaturated cyclic imide, which is important in organic synthesis and bioconjugation (modification of biological objects). Maleimides also mean a class of organic compounds formed from an unsubstituted maleimide molecule by replacing a hydrogen atom (N-H) with an alkyl or aryl radical (N-R). As a substituent R can also be a molecular compound (e.g., biotin), a fluorescent dye, an oligosaccharide, a nucleic acid, a reactive chemical group (to carry out a subsequent chemical reaction), a synthetic polymer (e.g., polyethylene glycol), or a protein molecule.Maleimides and their derivatives are formed by the reaction of maleic anhydride with amines, followed by dehydration of the non-cyclic amide formed at the first stage. The most important chemical property of maleimides is their exceptional reactivity in Michael conjugate addition and Diels-Alder reactions. Bismaleimides are a class of compounds containing two maleimide residues covalently bonded to each other. If the maleimide residue is connected to another reactive group (for example, an activated acid ester), the resulting compounds are called maleimide-based heterobifunctional reagents and are often used in the modification of proteins and other biological objects (bioconjugation). The authors of the presented work analyze the results of the study in the field of synthesis and determination of the areas of application of maleimides and their functionally substituted derivatives. In this work, we considered the main methods for the preparation of maleimide and noted the most important areas of its application, among which the use of maleimide derivatives as valuable monomers for the synthesis of functionalized polymers, as well as the synthesis of biologically active compounds, should be highlighted.
