Editorial: The Woodward‐Hoffmann Rules …︁

Abstract

…︁ were recognized as ground-breaking immediately upon their formulation, and “many chemists' eyes were opened when they read the original publication by Woodward and Hoffmann in 1965 and the legendary Review in Angewandte Chemie in 1969”. These are the opinions of contemporary witnesses whom we asked for advice as to whether Angewandte Chemie should publish an article by Roald Hoffmann in which he responds to E. J. Corey's claim to have given R. B. Woodward the incentive to develop what quickly became known as the Woodward–Hoffmann rules. In his acceptance speech during the award ceremony for the Priestley Medal, the highest accolade awarded by the American Chemical Society, in Spring 2004, E. J. Corey stated that: “On May 4, 1964, I suggested to my colleague R. B. Woodward a simple explanation involving the symmetry of the perturbed (HOMO) molecular orbitals for the stereoselective cyclobutene /1,3-butadiene and 1,3,5-hexatriene/cyclohexadiene conversions that provided the basis for the further development of these ideas into what became known as the Woodward-Hoffmann rules.” (published in Chem. Eng. News 2004, 82(13), 42–44). The audience/readership was astounded: Were the Woodward–Hoffmann rules not formulated by Woodward and Hoffmann after all? Should they rather be called the Corey–Woodward–Hoffmann rules? It was well known that Havinga, Schlatmann, and especially Oosterhoff had set some very important precedents (see: J. Berson, Chemical Creativity, Wiley-VCH, Weinheim, 1999, pp. 26–31). However, Corey's name had never before been mentioned in this context. As R. B. Woodward (Figure 1) died in 1979 at the age of 62, he can no longer say whether the conversation with Corey on May 4, 1964, enlightened him, gave him a decisive impetus, or merely confirmed his already well-thought-out ideas. R. B. Woodward with a Dreiding model of cobyric acid. Copyright: Harvard University Archives. It is most fortunate for the history of science in general and for chemistry in particular that—triggered by E. J. Corey's statement—Roald Hoffmann has penned his memories of that time. Entitled “A Claim on the Development of the Frontier Orbital Explanation of Electrocyclic Reactions”, his recollections of the early days of the development of the Woodward–Hoffmann rules and the time leading up to their publication can be read on page 6586 ff. It is unfortunate, but to be respected, that E. J. Corey, whom we of course asked to respond, chose not to say any more on the subject other than reiterating: “I am sure that the statement I made in my Priestley presentation is absolutely true, and at a later time I will present the full story.” For readers who practiced and shaped chemistry in the 1960s and 1970s, Roald Hoffmann's contribution makes compelling reading. For all readers, the article is an opportunity to ponder how new theories develop and how important communication is: both personal, in the form of conversations and correspondence, and formal, from presentations to publications. And how easily the sender and receiver can interpret the same information in a completely different manner. Angewandte Chemie is a suitable forum for this contribution: The above-mentioned Review (Angew. Chem. 1969, 81, 797–869; Angew. Chem. Int. Ed. Engl. 1969, 8, 781–853), in which the detailed Woodward–Hoffmann rules were lucidly presented, was published in this journal (see Figure 2). This Review is certainly one of the most-cited publications of Angewandte Chemie and, since the launch of the electronic Backfiles, has been one of the most-often downloaded files. Furthermore, the publication of a Correspondence article in a scientific journal has a more lasting character than in a magazine. May it now and in future find many readers and spur them on to reflect carefully on their own behavior. First page of the legendary Review by R. B. Woodward and R. Hoffmann in Angewandte Chemie. Dr. Peter Gölitz Editor P.S. Another recommended read in this issue is the Essay by Amir Hoveyda, who delves into Primo Levi's literary masterpiece, The Periodic Table (page 6592 ff.).