Aziridine ring-opening reactions with chiral enolates. Stereocontrolled synthesis of 5-substituted-3-methyl-pyrrolidin-2-ones

A procedure for performing stereocontrolled aziridine ring-opening reaction s with chiral enolates derived from (S,S)-(+)-pseudoephedrine amides has be en developed leading to gamma -aminoamides in good yields. The diastereosel ectivity of the reaction becomes controlled by the presence of the chiral a uxiliary on the enolate, although the stereogenic center contained in the s tructure of the aziridine has a striking influence on the stereochemical co urse of the reaction which results in the presence of the corresponding mat ched and mismatched combinations. Besides, the sense of the asymmetric indu ction of the chiral auxiliary has resulted to be the opposite to the one fo und with other type of electrophiles, although it is in good agreement with the trend observed in the reaction of the same kind of enolates with epoxi des. Finally, the obtained gamma -aminoamide adducts were converted into en antiopure gamma -amino acids, gamma -aminoesters, and pyrrolidin-2-ones usi ng easy to perform and high yielding reactions.