Maleimides Revisited: Reactivity, Selectivity, and Emerging Synthetic Strategies

Maleimides are α,β‐unsaturated cyclic imides that serve as electronically tunable α,β‐unsaturated scaffolds enabling controlled bond construction. Recent advances have redefined maleimides from simple Michael acceptors into programmable electrophilic platforms that enable controlled regio‐, stereo‐, and chemoselective bond formation. Over the past 5 years, this versatile scaffold has seen renewed attention in forming CC, CN, and CS bonds through transition‐metal‐catalyzed alkylation, alkenylation, organocatalytic and metal‐catalyzed conjugate additions, and diverse cycloaddition reactions. This review summarizes recent synthetic approaches to maleimide construction and functionalization, with particular focus on nucleophilic additions involving carbon and heteroatom pronucleophiles, enantioselective metal‐catalyzed transformations including C–H activation, and [4 + 2], [3 + 2], and [2 + 2] cycloaddition strategies leading to structurally complex frameworks. Emphasis is placed on methodologies that address long‐standing challenges in maleimide chemistry, including control of selectivity, retention of unsaturation, and expansion of post‐functionalization through emerging and hybrid catalytic strategies.