The asymmetric synthesis of β-lactams. Stereocontrolled asymmetric tandem Michael additions and alkylations of α,β-unsaturated acyl ligands bound to the chiral auxiliary [(η5-C5H5)Fe(CO)(PPh3)]
Davies SG., Dordor-Hedgecock IM., Sutton KH., Walker JC.
Michael addition of lithium benzylamide to the enantiomerically pure (S)-E-crotonyl complex of [(η5-C5H5)Fe(CO)(PPh3)] followed by trapping of the resultant enolate with methyl iodide or methanol occurs with high diastereoselectivity and gives after decomplexation the essentially optically pure (3R), (4S)-(-)-3,4-dimethyl- and (4S)-(-)-4-methyl-N-benzyl-β-lactams respectively. Similarly, tandem addition of lithium benzylamide and methylation of the corresponding enantiomerically pure R-(-)-acryloyl complex gave after decomplexation the essentially optically pure (3S)-(-)-3-methyl-N-benzyl-β-lactam. © 1986.