ChemInform Abstract: X=Y-ZH Systems as Potential 1,3-Dipoles. Part 17. Sequential Michael Addition-5-endo-trig Cyclization of Arylidene Imines of α-Amino Acid Esters.

ChemInform Abstract

Regiospecific Michael addition between the amino acid ester imines (I) and methyl acrylate or acrylonitrile (II) yields the adducts (III), which are cyclized to give mixtures of the polysubstituted proline esters (IV)-(VI). Mechanistic studies, involving chiral intermediates, show the formation of (IV) and (V) to be an example of a disfavored 5-(enolexo)-endo-trig process. The X-ray structure of (IVa) is determined (space group P2₁/c, Z=4).