Highly efficient and enantioselective cyclization of aromatic imines via directed C-H bond activation |
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Authors: | Thalji Reema K Ellman Jonathan A Bergman Robert G |
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Institution: | Center for New Directions in Organic Synthesis, Department of Chemistry, University of California-Berkeley, Berkeley, California 94720, USA. |
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Abstract: | The first highly enantioselective catalytic reaction involving aromatic C-H bond activation is communicated. Enantioselective cyclization of aromatic ketimines containing alkenyl groups tethered at the meta position of an imine directing group has been achieved using 5 mol % RhCl(coe)2]2 and 15 mol % of an (S)-binol-derived phosphoramidite ligand. Selectivities of up to 96% ee and up to quantitative yields were obtained. Moreover, the identified catalyst system enables the intramolecular alkylation reaction to be performed at temperatures 75 degrees C lower than our previously reported achiral system. The reaction can even be performed at room temperature for one of the optimal substrates. |
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