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- Title
Asymmetric Sequential Cu-Catalyzed 1,6/1,4-Conjugate Additions of Hard Nucleophiles to Cyclic Dienones: Determination of Absolute Configurations and Origins of Enantioselectivity.
- Authors
Blons, Charlie; Morin, Marie S. T.; Schmid, Thibault E.; Vives, Thomas; Colombel‐Rouen, Sophie; Baslé, Olivier; Reynaldo, Thibault; Covington, Cody L.; Halbert, Stéphanie; Cuskelly, Sean N.; Bernhardt, Paul V.; Williams, Craig M.; Crassous, Jeanne; Polavarapu, Prasad L.; Crévisy, Christophe; Gérard, Hélène; Mauduit, Marc
- Abstract
The first stereocontrolled Cu-catalyzed sequential 1,6/1,4-asymmetric conjugate addition (ACA) of C-metalated hard nucleophiles to cyclic dienones is reported. The use of DiPPAM (diphenylphosphinoazomethinylate) followed by a phosphoramidite as the stereoinducing ligands facilitated both high ee values for the 1,6-ACA and high de values for the 1,4-ACA reaction components, which thus gave enantioenriched 1,3-dialkylated moieties. The absolute configurations were determined by using vibrational circular dichroism (VCD) and optical rotatory dispersion (ORD) spectroscopy, in combination with DFT calculations and X-ray analysis. Interestingly, DFT calculations for the mechanism of enantioselective 1,6-addition by using an unprecedented Cu-Zn bimetallic catalytic system confirmed this attribution. Lastly, exploring intramolecular cyclization avenues for enantioenriched 1,3-dialkylated products provided access to the challenging drimane skeleton.
- Subjects
COPPER catalysts; CATALYSIS; NUCLEOPHILES; PHOSPHORAMIDITES; LIGANDS (Chemistry)
- Publication
Chemistry - A European Journal, 2017, Vol 23, Issue 31, p7515
- ISSN
0947-6539
- Publication type
Article
- DOI
10.1002/chem.201606034