Chelated enolates were found to be good nucleophiles for reactions
with acyl halides affording α-amino-β-keto esters.
In most cases, the reactions are over after a few minutes and preparatively
useful yields are obtained, independent of the protecting groups
and halides used. Besides acyl halides, also the corresponding imidazolides
can be used with similar success. With chloroformates as acylating
agents different protected amino malonates become accessible.
acylation - acyl halides - amino acids - amino
malonates - chelated enolates - ketones