The Many Chemists Who Could Have Proposed the Woodward‐Hoffmann Rules But Didn't: The Organic Chemists Who Knew of the Smoking Guns**

Abstract

Dedicated to the memory of John D. Roberts and his former student Andrew Streitwieser, Jr., teachers of mine and early proponents of the use of molecular orbital theory by organic chemists.

Revolutions in Chemistry: Assessment of Six 20th Century Candidates (The Instrumental Revolution; Hückel Molecular Orbital Theory; Hückel’s 4n + 2 Rule; the Woodward–Hoffmann Rules; Quantum Chemistry; and Retrosynthetic Analysis)

“…Perhaps it was the organic chemists who were uninvolved in the first 30 years of quantum chemical applications in their research, with notable exceptions. But for the reason now identified, ,, those notable exceptions, Dewar being one, did not bring their colleagues into quantum chemistry.…”

“…Whether arrow pushing and reasoning by analogy, steric effects, stereoelectronic effects, and conformational analysis, none of those heuristic models or any combination of them could (or can) explain the no-mechanism problem. An entirely new type of mechanism was needed though that was not obvious at the time to the practitioners. − And that mechanistic requirement was an application of quantum chemistry.…”

“…One major example: the solution to the no-mechanism problem discussed in section was not immediately forthcoming. Even those organic chemists who knew of the no-mechanism problem and also knew some measure of quantum chemistry, even those chemists did not think of and publish a quantum chemical solution. − These chemists included Jerome Berson, Breslow, William G. Dauben, Charles DePuy, Dewar, Doering, Roberts, and Zimmerman, all eventual members of the U.S. National Academy of Sciences, and several of whom ,,, had written books on quantum chemistry!…”

Why Woodward and Hoffmann? And Why 1965?**

“…[58,[156][157][158][159][160] By 1965, he had published extensively on the use of theory for organic reactions. [46,161,162] There were other chemists such as Andrew Streitwieser, John D. Roberts, and Saul Winstein who had experience with the application of MO theory to organic reactions (see Publications 6 [112] and 7 [163] in this series). And these chemists had experience, or shortly would have computational chemistry experience.…”

Introduction to “The Woodward‐Hoffmann Rules. From May 5, 1964, to November 30, 1964”**

“…[35] Other chemists discussed in Publication 7 include Arthur Cope, namesake of one of the prototypical examples of nomechanism reactions; Paul D. Bartlett, one of the top physical organic chemists of the era who published extensively on the nonconcerted 2 + 2 cycloadditions; Derek Barton, the discoverer of conformational analysis; John D. Roberts and Andrew Streitwieser, both of whom wrote textbooks on MO theory for organic chemists that were published in 1961; [36,37] and Michael J. S. Dewar who discovered perturbation molecular orbital theory in 1951 [38][39][40][41][42][43] and antiaromaticity in 1965. [44] * Publications 5, [32] 6 [45] and 7 [46] discuss the many chemists who were so very close to discovering the WÀ H rules but did not do so. Publications 8 [47] and 9 (in two parts [48,49] ) discuss the two chemists who did so.…”