Isoxazoles. XIX. Synthesis and Cleavage Reaction of Some 3, 4-Disubstituted Isoxazoles

抄録

Nine bicyclic isoxazolines (IVa-g and Va-b) were prepared by 1, 3-dipolar cycloaddition of nitrile oxides to the following heterocyclic olefins : 2, 3-and 2, 5-dihydrofurans, 5-methyl-2, 3-dihydrofuran, 2, 3-dihydropyran, and N-acetyl-2-piperidein. Acid-catalized cleavage of IVa-d gave the corresponding 4-substituted 3-phenylisoxazoles (VIa-c and IIIg). Nine 4-aminoalkyl-3-phenylisoxazoles (IIIa-i) were prepared for pharmacological testings in comparison with those of 3- and 5-aminoalkyl analogs (I and II). Base-catalized cleavage of the adducts (IVa-c and Va) was also investigated and in some cases the lactones (XIIa and XIIb) were obtained besides the isoxazoles (VIa and VIb). In this connection the Hofmann reactions of the bicyclic isoxazoline-3-carbon-amides (IVe'and IVf') were studied.