Copper-Catalyzed Asymmetric Reaction of Alkenyl Diynes with Styrenes by Formal 3 + 2 Cycloaddition via Cu-Containing All-Carbon 1,3-Dipoles: Access to Chiral Pyrrole-Fused Bridged 2.2.1 Skeletons

The generation of metal-containing 1,3-dipoles from metal carbenes represents a significant advance in 1,3-dipolar cycloaddition reactions. However, these transformations have so far been limited to reactions based on diazo compounds or triazoles as precursors. Herein, we disclose a copper-catalyzed enantioselective reaction of alkenyl N-propargyl ynamides with styrene derivatives by formal 3 + 2 cycloaddition via Cu-containing all-carbon 1,3-dipoles, which constitutes a novel way for the generation of metal-containing 1,3-dipoles via metal carbenes. This protocol allows the practical and atom-economical synthesis of valuable chiral pyrrole-fused bridged 2.2.1 skeletons in moderate to good yields (up to 90% yield) with excellent diastereoselectivities (dr > 50/1) and generally excellent enantioselectivities (up to >99% ee).