Electrogenerated chiral cationic glycine equivalents - Part 2: Chiral 3-methoxy-2,5-morpholinediones from (S)-α-hydroxy acids and dimethyl aminomalonate

Article abstract of DOI:10.1016/S0040-4020(98)00082-9

Chiral 3-methoxy-2,5-morpholinediones which are cyclic N,O-acetals have proved to be excellent chiral cationic amino acid equivalents, especially if larger nucleophiles are employed. They are easily obtained from dipeptolides formed between chiral α-hydroxy acids and dimethyl amino malonate via regioselective electrochemical methoxylation followed by intramolecular lactonizatian after decarboxylation. The lactonization can be performed quantitatively from the open-chain peptolide by condenzation under reduced pressure at elevated temperature. The easy separation of the desired amino acid and the α-hydroxy acid being the chiral auxiliary by extraction is valuable.