title: Cooperative activation of cyclobutanones and olefins leads to bridged ring systems by a catalytic [4 + 2] coupling.
abstract: Bridged ring systems are widely found in natural products, and successful syntheses of them frequently feature intramolecular Diels-Alder reactions. These reactions are subclassified as either type I or type II depending on how the diene motif is tethered to the rest of the substrate (type I are tethered at the 1-position of the diene and type II at the 2-position). Although the type I reaction has been used with great success, the molecular scaffolds accessible by the type II reactions are limited by the strain inherent in the formation of an sp(2) carbon at a bridgehead position. Here, we describe a complementary approach that provides access to these structures through the C-C activation of cyclobutanones and their coupling with olefins. Various alkenes have been coupled with cyclobutanones to provide a range of bridged skeletons. The ketone group of the products serves as a convenient handle for downstream functionalization.
authors: Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA.
authors: Haye Min
authors: HM
authors: Ko
authors: Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA.
authors: Guangbin
authors: G
authors: Dong
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D002384:Catalysis; D061565:Cycloaddition Reaction; D003503:Cyclobutanes / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry
chemical_list: D000475:Alkenes; D003503:Cyclobutanes; D012238:Rhodium