I have written earlier about dihydrocostunolide, and how in 1963 Corey missed spotting the electronic origins of a key step in its synthesis.. A nice juxtaposition to this failed opportunity relates to Woodward’s project at around the same time to synthesize vitamin B12. The step in the synthesis that caused him to ponder is shown below.
- E.J. Corey, and A.G. Hortmann, "The Total Synthesis of Dihydrocostunolide", J. Am. Chem. Soc., vol. 87, pp. 5736-5742, 1965. http://dx.doi.org/10.1021/ja00952a037