Gold(I)-Catalyzed Highly Diastereo- and Enantioselective Constructions of Bicyclo[3.2.1]oct-6-ene Frameworks via (4 + 3)-Cycloadditions

A one-pot construction of bicyclo[3.2.1]­oct-6-ene frameworks involves gold-catalyzed (4 + 3)-cycloadditions between 2-(1-alkynyl)-2-alken-1-ones and substituted cyclopentadienes; diastereoselectivity (dr >25:1) and enantioselectivity (up to 99.9% ee) are achieved with a chiral gold catalyst. Our DFT calculations suggest a three-step ionic mechanism for the cycloadditions of gold-containing 1,3-dipoles with cyclopentadienes, in which an exo-spatial arrangement is preferable.