Enantioselective Organocatalytic Syntheses and Ring‐Expansions of Cyclobutane Derivatives

Abstract The progress in enantioselective organocatalysis have enabled efficient and highly stereoselective syntheses of cyclobutane derivatives, through (2+2) annulation reactions, overcoming the geometrical constraints inherent to these small cyclic molecules. More importantly, and taking advantage of their strain‐releasing fragmentation, some cyclobutane derivatives, especially cyclobutanones and cyclobutenones, can now be regarded as versatile four‐carbon atoms units amenable to the enantioselective construction of larger rings by (4+n) annulation reactions to produce, five‐, six‐, seven‐ and eight‐membered cyclic products. These recent developments concerning the enantioselective synthetic chemistry of cyclobutane derivatives under organocatalytic conditions are reviewed herein.