Quaternary imine salts, hydrolysis

The asymmetric alkylation of glycine derivatives constitutes a general means of accessing a wide range of natural and unnatural oc-amino acids.111 Recently it has been established that the quaternary ammonium salt, (lS,2S,4S,5/ ,l / )-l-anthracen-9-yl)methyl-2-[benzyloxy(quinolin-4-yl)methyl]-5-ethyl-l-azoniabicyclo [2.2.2]octane bromide, is a highly effective catalyst in the asymmetric liquid-liquid phase-transfer alkylation of tert-butyl AI-(diphenylmethylene)glycinate. Subsequent hydrolysis of the imine provides access to a wide range of a-amino acid fcrt-butyl... 

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