Volume 54, Issue 41 pp. 12149-12152
Communication

Chiral Cyclopentadienyl Iridium(III) Complexes Promote Enantioselective Cycloisomerizations Giving Fused Cyclopropanes

Dr. Michael Dieckmann

Dr. Michael Dieckmann

Laboratory of Asymmetric Catalysis and Synthesis, EPFL SB ISIC LCSA, BCH 4305, 1015 Lausanne (Switzerland) http://isic.epfl.ch/lcsa

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Yun-Suk Jang

Yun-Suk Jang

Laboratory of Asymmetric Catalysis and Synthesis, EPFL SB ISIC LCSA, BCH 4305, 1015 Lausanne (Switzerland) http://isic.epfl.ch/lcsa

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Prof. Dr. Nicolai Cramer

Corresponding Author

Prof. Dr. Nicolai Cramer

Laboratory of Asymmetric Catalysis and Synthesis, EPFL SB ISIC LCSA, BCH 4305, 1015 Lausanne (Switzerland) http://isic.epfl.ch/lcsa

Laboratory of Asymmetric Catalysis and Synthesis, EPFL SB ISIC LCSA, BCH 4305, 1015 Lausanne (Switzerland) http://isic.epfl.ch/lcsaSearch for more papers by this author
First published: 27 August 2015
Citations: 77

Graphical Abstract

Be selective! A set of chiral CpxIrIII complexes (Cpx=chiral cyclopentadienyl) based on atropchiral cyclopentadienyl ligands are presented. The complexes, in particular the tert-butoxy-substituted derivative (see picture), are shown to promote the asymmetric cycloisomerization of enynes to form fused cyclopropanes with high enantioselectivities.

Abstract

The cyclopentadienyl (Cp) group is a very important ligand for many transition-metal complexes which have been applied in catalysis. The availability of chiral cyclopentadienyl ligands (Cpx) lags behind other ligand classes, thus hampering the investigation of enantioselective processes. We report a library of chiral CpxIrIII complexes equipped with an atropchiral Cp scaffold. A robust complexation procedure reliably provides CpxIrIII complexes with tunable counterions. In a proof-of-concept application, the iodide-bearing members are shown to be highly selective for enyne cycloisomerization reactions. The dehydropiperidine-fused cyclopropane products are formed in good yields and enantioselectivities.

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