Design and Synthesis of a [2.2]Paracyclophane‐based Planar Chiral Dirhodium Catalyst and its Applications in Cyclopropanation Reaction of Vinylarenes with <i>α</i>‐Methyl‐<i>α</i>‐Diazo Esters
Christoph Zippel, Zahid Hassan, Martin Nieger, Stefan Bräse
Abstract
Abstract A planar chiral dirhodium paddlewheel complex Rh 2 ( S p −PCP) 4 based on the [2.2]paracyclophane has been synthesized for the challenging cyclopropanation of venylarene derivatives with tert ‐butyl α ‐diazo propionates. The homobimetallic rhodium catalyst relies on the high steric demand and rigidity of [2.2]paracyclophane that favors the cyclopropanation of 1‐aryl substituted, 1,1‐disubstituted and benzannulated alkenes over β ‐hydride migration at room temperature with high diastereoselectivity. magnified image
Topics & Concepts
CyclopropanationDiazoChemistryRhodiumSteric effectsCatalysisArylPlanar chiralityMedicinal chemistryEnantioselective synthesisStereochemistryOrganic chemistryAlkylCyclopropane Reaction MechanismsCatalysis for Biomass ConversionAsymmetric Hydrogenation and Catalysis