摘要:
The reaction of 4-acetyl-5-methyl-3-isoxazolyl carboxylate with a variety of hydrazines and semicarbazides yielded molecules which are viable antagonist candidates for the AMPA receptor. Molecular modeling studies used in conjunction with the x-ray crystal structures of these derivatives show a close correlation between the hydrogen bonding characteristics of AMPA with that of the hydrazone and semicarbazone isoxazole derivatives. Uncyclized hydrazones and semicarbazones (1-5) were formed by using corresponding hydrazines and semicarbazides containing strong electron withdrawing groups to prevent cyclization with the ethyl ester. The crystals of 1 are orthorhombic with a = 14.2997(3), b = 15.4112(4), c = 16.0153(4) Angstrom, Z = 8, and space group Pbca; 2 monoclinic with a = 19.738(2), b = 10.4155(7), c = 15.583(1) Angstrom, beta = 92.348(2)degrees, Z = 8, and space group C2/c; 3 triclinic with a = 8.3365(5), b = 8.4930(5), c = 12.2379(7) Angstrom, alpha = 92.568(2), beta = 102.229(2), gamma = 104.449(1)degrees, Z = 2, and space group P(1)over bar.