Stereoselective Ring Expansion of Vinyl Oxiranes: Mechanistic Insights and Natural Product Total Synthesis

摘要

The central part of our research program is the development of broadly applicable atom-efficient synthetic methods to generate structural complexity. We recently reported a new copper-catalyzed ring expansion of vinyl oxiranes using commercially available, structurally simple, and air-stable copper(II) catalysts. These studies demonstrated the success of this reaction for a broad range of substrates. Missing from these early studies were experiments focused on assessing the stereoselective potential of the ring expansion. The studies presented herein are aimed at addressing this point to learn if the oxirane C-O bond, which is broken during the ring expansion, could be stereoselectively transferred to the olefin terminus. Moreover, an added benefit to the proposed studies would be critical mechanistic insights that could shed additional light on the exact mechanism of this unique catalytic ring-expansion reaction. If vinyl oxiranes can indeed be stereoselectively ring expanded using copper catalysts then the practical benefits of this new reaction would be significantly expanded.