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 reactions with chiral enolates derived from (S,S)-(+)-pseudoephedrine amides has been developed leading to gamma-aminoamides in good yields. The diastereoselectivity of the reaction becomes controlled by the presence of the chiral auxiliary on the enolate, although the stereogenic center contained in the structure of the aziridine has a striking influence on the stereochemical course of the reaction which results in the presence of the corresponding matched and mismatched combinations. Besides, the sense of the asymmetric induction of the chiral auxiliary has resulted to be the opposite to the one found 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 epoxides. Finally, the obtained gamma-aminoamide adducts were converted into enantiopure gamma-amino acids, gamma-aminoesters, and pyrrolidin-2-ones using easy to perform and high yielding reactions.
Vicario
J L
JL
Departamento de Química Orgánica II, Facultad de Ciencias, Universidad del País Vasco/Euskal Herriko Unibertsitatea, P.O. Box 644, E-48080 Bilbao, Spain.
Badía
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D
Carrillo
L
L