Copper-catalyzed asymmetric conjugate addition of alkenyl- and alkylalanes to α,β-unsaturated lactams.
Alkenyl and alkyl groups have been successfully introduced to six-membered α,β-unsaturated lactams via a copper-catalyzed asymmetric 1,4-addition of the corresponding alanes. Moderate to good yields and good to excellent enantioselectivities are achieved by using a combination of the very cheap copper(II) naphthenate and a readily available phosphine amine ligand. The creation of an all-carbon quaternary stereogenic center, via Michael addition to a trisubstituted conjugated lactam, is also disclosed for the first time.
Department of Organic Chemistry, University of Geneva, Quai Ernest Ansermet 30, CH-1211 Geneva 4, Switzerland.
Pierre
P
Cottet
Daniel
D
Müller
Alexandre
A
Alexakis