Kenichi Fukui, Frontier Molecular Orbital Theory, and the Woodward‐Hoffmann Rules. Part II. A Sleeping Beauty in Chemistry†**

Abstract In 1964, Kenichi Fukui published a chapter in a book honoring the career of Robert S. Mulliken. While most of that chapter is a review of Fukui's previously published research dealing with frontier molecular orbital theory and organic reactions, one section provided a frontier molecular orbital explanation of the mechanism of the Diels‐Alder reaction. Fukui concluded that the “symmetry relation of wave functions of both dienes and dienophiles” control the course of this reaction. Thus, Fukui's paper was a precursor to Woodward and Hoffmann's 1965 papers that proposed orbital symmetry control of what would later be termed “pericyclic reactions.” Fukui published numerous papers in the 1950s and 1960s, many of which were expositions of his research in theoretical chemistry. Eight of those Fukui papers were direct precursors to his breakthrough 1964 publication. This paper presents the intellectual and scientific path that Fukui took from the early 1950s to 1964 to his award‐winning publication.