4,5-Dihydro-7H-pyrano[3,4-c]isoxazoles (II, III), bicyclic isoxazoles, have been designed and synthesized via intramolecular [2+3] cycloaddition of nitroether 3 as a key step. The broad spectrum of fungicidal activities of pyranoisoxazoles (II, III) were observed on plant pathogens at 250 ppm. Pyranoisoxazole II, III with chlorophenyl at 6-position and bromomethyl or alkylated oxime group at 3-position gave effective control of plant diseases.