First Desymmetrization of a Centrosymmetric Molecule in Natural Product Synthesis: Preparation of a Key Fragment in the Synthesis of Hemibrevetoxin B This work was supported by the University of Leeds (through a Brotherton Scholarship to J.M.H.) and Pfizer. We are extremely grateful to Professor T. Nakata of the Institute of Physical and Chemical Research (RIKEN), Saitama, Japan, for providing us with the NMR spectra of the epoxide 2, the Royal Society for a grant, and AstraZeneca for strategic research funding.