Diastereoselective Synthesis of alpha,alpha-Disubstituted gamma-Carboxypyroglutamates via Sm(III)-Azomethine Ylide Cycloadditions.
Sm(III)-azomethine ylides 2 have been generated from ketones 1. Cycloaddition of ylides 2 with alpha,beta-unsaturated esters 3 through a transition state chelation-controlled by the metal allowed for the asymmetric synthesis of gamma-carboxypyroglutamates having a quaternary alpha-carbon that are potentially useful in the synthesis of neuroprotective agents.
Alvarez-Ibarra
Carlos
C
Departamento de Química Orgánica I, Facultad de Química, Universidad Complutense, 28040 Madrid, Spain.
Csákÿ
Aurelio G.
AG
López De Silanes
Isabel
I
Quiroga
M. Luz
ML