Rhodium-Catalyzed Enal Transfer Reactions of Diazoenals: Application to Diastereoselective Synthesis of Dienal-Cyclopropanes

Abstract Vinyl cyclopropanes are valuable functional groups in drugs or natural products as well as established precursors to trigger a rich variety of synthetic transformations. However, their reactive nature makes their installation challenging. We herein present a modular access to highly diastereoselective (>20:1) dienal-cyclopropanes from rhodium-enalcarbenoids and styrenes under mild conditions. This protocol was extended to synthesize a biologically relevant substituted pyrroline scaffold. Overall, this Rh (II)-catalyzed cyclopropanation exhibits good functional group tolerance, facile scalability, and selective access to a diverse range of dienal cyclopropane motifs featuring an all-carbon ε-quaternary stereocenter.