Confinement as a Unifying Element in Selective Catalysis

Summary Catalysis has fascinated scientists for centuries and is one of the main pillars of the modern world economy. Achieving high reactivity and selectivity is a crucial requirement of heterogeneous and homogeneous organic, metallic, and biological catalysts. Here, we highlight an underlying principle that is relevant to the reactivity and selectivity of all types of catalysts—“confinement,” the shaping of a catalyst's active site. While this aspect has been well recognized within the fields of heterogeneous and enzymatic catalysis, and has been invoked in supramolecular systems, confinement has been less appreciated in the design of small-molecule catalysts. We identify confinement as a unifying element in the science of selective catalysis, reaching beyond the traditional boundaries of the individual subfields. A particular emphasis is given to the latest developments in the area of organocatalysis.