Asymmetric alkylation of glycine imines using in situ generated phase-transfer catalysts

In this paper we report an investigation into the possibility of effecting the asymmetric alkylation of glycine imines using chiral quaternary ammonium salt catalysts that are generated in situ. It is demonstrated that O-alkyl N-alkyldihydrocinchonidinium salts can be assembled from the parent alkaloid under the reaction conditions required for the liquid–liquid phase-transfer alkylation of glycine imines, and that reactions performed in this way give enantioselectivities comparable to those obtained using pre-prepared catalysts. Utilization of this methodolgy in the generation and screening of catalyst libraries is also demonstrated.