Assembly of Molecular Complexity by Carbene Organocatalytic Multicomponent Reactions Involving α,β‐Unsaturated Aldehydes

The pursuit of molecular complexity is central to modern organic synthesis, as complex molecules are essential across various fields. The development of catalytic multicomponent transformation strategies provides an efficient approach for the rapid and selective construction of complex molecular frameworks. Over the past decades, N‐heterocyclic carbene organocatalysis has emerged as a powerful tool in multicomponent reactions (MCRs), enabling precise control over selectivity, stereochemistry, and functional group compatibility that significantly facilitate the assembly of complex molecular structures. This review provides an overview of recent advancements in carbene‐catalyzed MCRs involving α,β‐unsaturated aldehydes, with an emphasis on reactions incorporating three or more reactants. These transformations are categorized into electron‐pairing and radical pathways, with a detailed discussion of their mechanisms, scope, and limitations. Ultimately, this review aims to advance the development of catalytic strategies that leverage carbene organocatalysis to enable the efficient synthesis of value‐added molecules from simple precursors.