N-sulfinyl metalloenamine conjugate additions: asymmetric synthesis of piperidines.
[reaction: see text] The first examples of conjugate additions of N-tert-butanesulfinyl metalloenamines are reported. Highly stereoselective conjugate additions (97:3 to 99:1 dr) were observed between metalloenamines derived from N-sulfinyl ketimines and alpha,beta-unsaturated ketones bearing either alkyl or aryl substituents. The conjugate addition products could rapidly be converted with high diastereoselectivity to 2,4,6-trisubstituted piperidines, which are difficult to access by other methods.
Peltier
Hillary M
HM
Center for New Directions in Organic Synthesis, Department of Chemistry, University of California, Berkeley, California 94720, USA.
Ellman
Jonathan A
JA