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DOI: 10.1055/s-0028-1083447
New Chiral Diene Ligands for Iridium-Catalyzed [3+2] Annulation
Contributor(s):Hisashi Yamamoto, Cheol Hong CheonKyoto University, Japan
C 2-Symmetric Tetrafluorobenzobarrelenes as Highly Efficient Ligands for the Iridium-Catalyzed Asymmetric Annulation of 1,3-Dienes with 2-Formylphenylboron Reagents
Tetrahedron: Asymmetry 2008, 19: 1778-1783
Publication History
Publication Date:
23 October 2008 (online)
Key words
chiral diene ligands - iridium - [3+2] annulation
Significance
The authors have developed new C 2-symmetric chiral diene ligands bearing a tetrafluorobenzobarrelene via a [4+2] cycloaddition of tetrafluorobenzyne. The diene ligands realized the iridium-catalyzed enantioselective [3+2] annulation of 1,3-dienes with 2-formylphenylboron reagents to afford 1-indanol derivatives in high yields and with high enantioselectivities. The required chiral ligand was prepared and additionally synthesized using a chiral column.
Comment
Recently, the authors reported the iridium-catalyzed [3+2] annulation of 1,3-dienes (J. Am. Chem. Soc. 2007, 129, 7506). Later, their attempts to extend this methodology to an enantioselective version by using chiral bicyclo[2,2,2]octadiene ligands instead of the cod ligand were not successful due to low coordination ability of the ligand to iridium. In this work, they prepared new C 2-symmetric electron-deficient chiral diene ligands possessing high coordination ability towards iridium and successfully applied this complex with iridium to asymmetric annulations.