On the Structural Assignments Underlying R. B. Woodward's Most Personal Data That Led to the Woodward-Hoffmann Rules: Subramania Ranganathan's Key Role and Related Research by E. J. Corey and A. G. Hortmann

The Many Chemists Who Could Have Proposed the Woodward-Hoffmann Rules (Including Roald Hoffmann) But Didn't: The Theoretical and Physical Chemists†

It is a reasonable question to ask, why, as of 1965 when the five Woodward-Hoffmann communication appeared, did no other physical chemist or chemical physicist or theoretical chemist discover the orbital symmetry rules for all pericyclic reactions? Two theoretical chemists - Luitzen Oosterhoff (in 1961) and Kenichi Fukui (in 1964) had discovered portions of the orbital symmetry rules; their stories appear in the papers immediately preceding this paper which is Paper 5 in a 27-paper series on the history of Woodward-Hoffmann rules. Concise yet telling stories of 19 other chemists who could have, might have, perhaps even should have discovered the Woodward-Hoffmann rules are presented with explanations as to why they did not do so. Social, political, and scientific explanations will summarize the analyses.

History of the Woodward-Hoffmann Rules. The No-Mechanism Puzzle

This is Paper 2 in the 27-paper series on the history of the development of the Woodward-Hoffmann rules. Paper 2 takes the reader back to the 1950s and early 1960s, before the publication of the first Woodward-Hoffmann paper in January 1965. The scope of the pericyclic no-mechanism problem is described along with many of the key "hints" or "clues" to orbital symmetry control that were available in the literature prior to 1965. A chronology of reactions with alternating stereospecificities is provided. A second chronology of alternating theoretical hints is provided, e. g., 4n+2 versus 4n. Another chronology is provided, that of the development of frontier molecular orbital theory, with and without phases and nodes. A tabulation is provided of 36 instances in which the MOs of 1,3-butadiene were reported in the literature. A knowledge of the MOs of 1,3-butadiene, plus a knowledge of some of the alternating stereospecific reactions, could have led many chemists to the solution of the pericyclic no-mechanism problem before Woodward and Hoffmann.

Divergent Synthesis of Highly Substituted Pyridines and Benzenes from Dienals, Alkynes, and Sulfonyl Azides

Divergent synthesis is extremely important for the highly efficient preparation of structurally diverse target molecules. Herein, we describe a multicomponent cascade reaction, which allows access to highly substituted pyridines and benzenes by combining four individual steps in a one-pot manner from the same set of readily available starting materials. The azepine intermediates were first used as the precursors for 6π-electrocyclization to construct highly substituted pyridines and benzenes in a tunable manner.