Palladium(0)-Catalyzed Isomerization Reactions of Aziridines Bearing an α,β-Unsaturated Ester Group: A Thermodynamic Preference for Chiral Alkyl (2<i>E</i>)-4,5-<i>cis</i>-4,5-Epimino-<i>N</i>-(alkyl- or arylsulfonyl) 2-Enoates over the Other Three Stereoisomers
Palladium(0)-catalyzedreactions of five sets of four stereoisomeric 4,5-epimino-N-(methanesulfonyl) or -N-(arylsulfonyl) 2-enoates reveal that 4,5-cis-(2E)-isomers are thermodynamically more stable than other isomers, in accord with calculations. A highly stereoselective synthesis of (E)-alkene dipeptide isosteres having the desired stereochemistries from unwanted stereoisomeric 4,5-epimino-N-(arylsulfonyl)
A thermodynamic preference of chiral cis-γ,δ-epimino-(E)-α,β-unsaturated esters over other stereoisomers: Synthetically useful Pd(0)-catalyzed equilibrated reactions of aziridines bearing an α,β-unsaturated ester group
A practical synthesis of chiral N-arylsulfonyl-cis-γ,δ-epimino-(E)-α,β-enoates, key intermediates for the synthesis of (E)-alkene dipeptide isosteres via Pd(0)-catalyzedequilibratedreactions, has been successfully achieved by exposing N-arylsulfonyl-γ,δ-epimino-α,β-unsaturatedesters to a catalytic amount of Pd(PPh3)4 in THF at 0 ∼ 20 °C.