Aryl alkyl ethers, which are widely used throughout the chemical industry, are typically produced via the Williamson ether synthesis. Olefin hydroaryloxylation potentially offers a much more atom-economical alternative. Known acidic catalysts for hydroaryloxylation, however, afford very poor selectivity. We report the organometallic-catalyzed intermolecular hydroaryloxylation of unactivated olefins by iridium "pincer" complexes. These catalysts do not operate via the hidden Brønsted acid pathway common to previously developed transition-metal-based catalysts. The reaction is proposed to proceed via olefin insertion into an iridium-alkoxide bond, followed by rate-determining C-H reductive elimination to yield the ether product. The reaction is highly chemo- and regioselective and offers a new approach to the atom-economical synthesis of industrially important ethers and, potentially, a wide range of other oxygenates.
Olefin Hydroaryloxylation Catalyzed by Pincer-Iridium Complexes. -An intensive investigation of the reaction mechanism is presented. DFT calculations provide energies, reaction path, and transition states supporting a mechanism proceeding via insertion of olefin into the iridium-aryloxide Ir-O bond. -(HAIBACH, M.; GUAN, C.; WANG, D. Y.; LI, B.; LEASE, N.; STEFFENS, A. M.; KROGH-JESPERSEN*, K.; GOLDMAN, A. S.; J. Am. Chem. Soc. 135 (2013) 40, 15062-15070, http://dx.doi.org/10.1021/ja404566v ; Dep. Chem. Chem. Biol., Rutgers State Univ. N. J., New Brunswick, NJ 08903, USA; Eng.) -Y. Steudel 09-074
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