Spiro[3.3]heptane: A Versatile sp3‐Rich Scaffold and its Synthetic Routes

Among the growing class of sp³‐rich scaffolds, spiro[3.3]heptane stands out for its rigid, 3D structure and favorable physicochemical properties. Its 3D saturated scaffold enables access to unique, nonplanar chemical space and has been explored as a saturated bioisostere of benzene in drug design. In this review, an overview of synthetic strategies developed to construct spiro[3.3]heptane derivatives is provided. These approaches are grouped according to key synthetic strategies, including formal [2+2] cyclization and bond disconnections at C1C2 or C4 (spiro‐carbon) positions. Representative examples are presented to illustrate each method's key transformations and strategic bond formations. This review is intended to support synthetic chemists interested in employing spiro[3.3]heptane as a building block and to provide a foundation for further exploration of this emerging motif.