Mixed aldehyde condensations on copper glycinate

Glycine coordinated to cupric ions reacts in basic solution with a stoichiometric quantity of aldehydes to give β-hydroxyaminoacids. When the reaction contains a mixture of aldehydes, one of them being acetaldehyde, threonine is produced in the solution together with a variable amount of the bulkier substituted serine. An intermediate complex may be isolated which affords a larger proportion of substituted serines with predominance of the threo isomers. Acetaldehyde and benzaldehyde give a 66% yield of threo β-phenylserine.