SmI2-Mediated Coupling of Nitrones and tert-Butanesulfinyl Imines with Allenoates: Synthesis of β-Methylenyl-γ-lactams and Tetramic Acids
journal contributionposted on 20.04.2012, 00:00 by Chu-Pei Xu, Pei-Qiang Huang, Sandrine Py
Nitrones and tert-butanesulfinyl imines undergo conjugate addition to alkyl allenoates under SmI2-mediated reductive coupling conditions to produce novel β-methylenyl-substituted γ-amino esters. The latter were readily transformed into the corresponding β-methylenyl-γ-lactams by simple zinc reduction (N-hydroxy amines) or by acid hydrolysis (sulfinamides). The diastereoselective preparation of various β-methylenyl-γ-lactams offers a route to tetramic acids, the key structural features of an important class of bioactive natural products.