Enantioselective synthesis of (S)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propanoic acid (S)-AMPA

(S)-AMPA (11) is an isoxazole containing α-amino acid used for selectively labeling the homonymous excitatory amino acid (EAA) receptor. Until now only enzymatic methods have been devised for its preparation. An asymmetric synthesis of (S)-AMPA is reported which exploits the formation of 3-bromo-4-hydroxymethyl-5-methylisoxazole intermediate 3 in a potassium fluoride promoted 1,3-dipolar cycloaddition and the application of the bislactim ether methodology for introducing the chiral α-amino acid center.