1202007-27-9Relevant academic research and scientific papers
Diastereo- and enantioselective synthesis of functionalized β-lactams from oxiranecarbaldimines and lithium ester enolates
Michel, Kristin,Froehlich, Roland,Wuerthwein, Ernst-Ulrich
experimental part, p. 5653 - 5665 (2010/03/03)
The addition of nucleophiles like lithium ester enolates 6 to oxiranecarbaldimines 1 leads to new oxiranyl-functionalised β-lactams 7 in excellent enantio- and diastereoselectivity. A simple one-pot procedure affords β-lactams (azetidin-2-ones) with three or four neighbouring stereogenic centres and unlike preference. Products resulting from oxirane ring-opening reactions were not observed. An enantiomerically enriched example (2S,3S)-1g gave the corresponding β-lactam (S,S,R)-7f in excellent enantiomeric excess. According to quantum chemical calculations the observed diastereoselectivity is the result of a diastereofacial differentiation of the two faces of the iminic double bond in the transition state.
