3-Isoxazolepropanoic acid, 5-methyl- 3-Methyl-5-isoxazolepropionic acid 5(3)-Methyl-3(5)-isoxazolepropionic acid 5-Methyl-3-isoxazolepropanoic acid 5-Methyl-3-isoxazolepropionic acid 80073-32-1 MeIPA