Synthesis of Sterically Hindered Ortho-Substituted Tetraphenylethenes. Electronic Effects in the McMurry Olefination Reaction

Contrary to literature consensus, the McMurry olefination reaction can be extended to the direct synthesis of sterically encumbered tetrakis(2-substituted) tetraphenylethenes from the corresponding 2,2‘-disubstituted benzophenones. The reaction exploits previously unrecognized substrate-based electronic effects that dominate over otherwise controlling steric considerations and provides highly efficient access to derivatives of tetrakis(2-hydroxyphenyl)ethene, a novel preorganized ligand system for polymetallic coordination chemistry and catalysis.