Synthesis and Glutamate-Agonistic Acitivity of (S)-2-Amino-3-(2,5-dihydro-5-oxo-3-isoxazolyl)-propanoic Acid Derivatives

(S)-2-Amino-3-(2,5-dihydro-5-oxo-3-isoxazolyl)propanoic acid, (3a) and its analogs (3b-h) were prepared and evaluated for glutamate receptor-agonistic and antifungal activities. Several(S)-and (R)-2-amino-3-isoxazolylpropanoic acid derivatives (3a-d) were synthesized starting with (S)-and (R)-N-tert-butoxycarbonyaspartic acid α-methyl esters (4,n=1) by means of Masamune's chain extension reaction followed by isoxazolone formation with hydroxylamine and subsequent deprotection reactions. Furthermore, (S)-and (R)-N-tert-butoxycarbonylglutamic acid α-methyl esters (4,n=2) were converted to (S)- and (R)-2-amino-4-isoxazolylbutyric acid derivatives (3e-h) via the same sequence of reactions.