Computational Elucidation of the Origins of Reactivity and Selectivity in Non-Aldol Aldol Rearrangements of Cyclic Epoxides

Abstract

The non-aldol aldol reaction of the isomeric epoxy silyl ethers is controlled by the conformation of the transition states leading to an internal hydride shift. One isomer rearranges to the β-silyloxy ketone whereas the other isomer gives a β-elimination product. Theoretical calculations show that the substrates with substituents that favor the formation of the chairlike transition state rearrange normally while those that do not undergo elimination instead