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

Abstract

In the early 1960s, as part of R. B. Woodward's isoxazole route to vitaminB 12 ,S ubramania Ranganathan uncovered two coupled sets of stereospecific reactions, at hermal set and ap hotochemicals et. These four reactions illustrated the alternatingc onfigurations that were the majord ata points that prompted the solution of the no-mechanism problem. Though Ranganathan's reactions played am ajor role, according to Woodward,i nt he development of the Woodward-Hoffmann rules, they were published only as part of the documentation of al ectureg iven by Woodward in 1966. The authors of this paper have uncovered Subramania Ranganathan's 1964 postdoctoral report and have used modern quantum chemical theory to predict the 1 HNMR spectra for Ranganathan's key compounds, providing support for the structure assignments madeb yW oodward and Ranganathan. As imilar set of alternating, stereospecific reactions was observed by E. J. Corey and Alfred Hortmann in their 1963t otal synthesis of dihydrocostunolide. We also have applied the computational process used for Ranganathan'sc ompounds to Hortmann's compounds, now also includingt he calculationo fc oupling constants, and find computational support for Coreya nd Hortmann's structure assignments.

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

“…From 1962 to June 1964, Ranganathan was a postdoctoral with Woodward participating in the research toward the total synthesis of vitamin B 12 . [263] As Woodward characterized the most relevant (to the Woodward-Hoffmann rules) of Ranganathan's experimental results (Figure 35), Figure 35. A reproduction of a scheme from R. B. Woodward's 1967 autobiographical discussion of the origins of the Woodward-Hoffmann rules.…”

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

“…Ranganathan was Woodward's postdoctoral student who discovered the alternating stereospecific reactions while pursuing the oxazole route to vitamin B 12 (Figure 25). [105,196] Jos Schlatmann was the co-author of the Havinga paper in which Oosterhoff's December 1960 suggestion was published. [40,197] Alfred Hortmann, as discussed in Paper 6 of this series, [4] had lectured on Oosterhoff's suggestion to the Corey group.…”

“…The coupled stereospecific reactions observed by Subramania Ranganathan's 1963-1964 research on the isoxazole route to vitamin B 12 . [105,196] Ranganathan's results became R. B. Woodward's fifth mysterious reaction and ultimately led to the Woodward-Hoffmann rules. [64,80] That being said, Lehn returned to France in September or October 1964, perhaps before Ranganathan had completed his structure elucidations.…”

“…Probably not, as Hoffmann had temporarily shelved his collaborative research with Woodward from late June to mid‐October 1964 [56] . On the other hand, had Dauben talked with Subramania Ranganathan about his research, [105] Dauben might have become interested in the pericyclic no‐mechanism reaction. But that did not happen.…”

“… The coupled stereospecific reactions observed by Subramania Ranganathan's 1963–1964 research on the isoxazole route to vitamin B 12 [105,196] . Ranganathan's results became R. B. Woodward's fifth mysterious reaction and ultimately led to the Woodward‐Hoffmann rules [64,80] …”