In the early 1960s, as part of R. B. Woodward's isoxazole route to vitamin B12 , Subramania Ranganathan uncovered two coupled sets of stereospecific reactions, a thermal set and a photochemical set. These four reactions illustrated the alternating configurations that were the major data points that prompted the solution of the no-mechanism problem. Though Ranganathan's reactions played a major role, according to Woodward, in the development of the Woodward-Hoffmann rules, they were published only as part of the documentation of a lecture given 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 H NMR spectra for Ranganathan's key compounds, providing support for the structure assignments made by Woodward and Ranganathan. A similar set of alternating, stereospecific reactions was observed by E. J. Corey and Alfred Hortmann in their 1963 total synthesis of dihydrocostunolide. We also have applied the computational process used for Ranganathan's compounds to Hortmann's compounds, now also including the calculation of coupling constants, and find computational support for Corey and Hortmann's structure assignments.
Keywords: Corey; Woodward-Hoffmann rules; dihydrocostunolide; structure determination; vitamin B12.
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