Highly efficient and enantioselective cyclization of aromatic imines via directed C-H bond activation.
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.
Thalji
Reema K
RK
Center for New Directions in Organic Synthesis, Department of Chemistry, University of California-Berkeley, Berkeley, California 94720, USA.
Ellman
Jonathan A
JA
Bergman
Robert G
RG
D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D006859:Hydrogen / Q000737:chemistry*; D007097:Imines / Q000737:chemistry*; D007099:Imipramine / Q000031:analogs & derivatives* / Q000737:chemistry; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D013237:Stereoisomerism; D013696:Temperature
D007097:Imines; D008024:Ligands; D002244:Carbon; D006859:Hydrogen; D007099:Imipramine; C027682:ketipramine