Abstract
Highly site-selective Mukaiyama-Michael additions of silyl
ketene imines to α,β-unsaturated aldehydes and
ketones are described. The combination of silicon tetrachloride
and a chiral bisphosphoramide provides an effective catalyst system
for promoting the addition of silyl ketene imines to a variety of
aromatic enals with high site selectivity and moderate to good diastereo-
and enantioselectivity.
Key words
Lewis base - asymmetric catalysis - Michael
addition - aldehydes - quaternary carbon
References and Notes
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The crystallographic coordinates of 7 have been deposited with the Cambridge
Crystallographic Data Centre (CCDC); deposition no. 776146. These
data can be obtained free of charge from the CCDC via www.ccdc.cam.ac.uk/data_request/cif.
<A NAME="RY00710ST-22">22 </A>
For computational and mechanistic
studies, see ref. 15g. For a full kinetic analysis, see ref. 19.
