Isoxazole derivatives and process for producing the same

A process of producing an isoxazole derivative represented by the following formula (I):

• (wherein:
• R1 represents a hydrogen atom, optionally substituted C1-C20 hydrocarbon group, or —C(═O)OR1a (wherein R1a is an optionally substituted C1-C10 alkyl group, optionally substituted C2-C10 alkenyl group or optionally substituted C2-C10 alkynyl group);
• R2 and R3, which may be the same or different, each independently represents a hydrogen atom, halogen atom, hydroxy group, optionally substituted C1-C20 alkyl group, or optionally substituted C6-C20 aryl group;
• R4, which may be the same or different, each independently represents a hydrogen atom, halogen atom, hydroxy group, cyano group, nitro group, optionally substituted amino group, optionally substituted C1-C20 hydrocarbon group, optionally substituted C1-C10 alkoxy group, optionally substituted C1-C10 acyl group or optionally substituted 5- to 7-membered heterocyclic group;
• R5 represents a hydrogen atom, halogen atom, hydroxy group, optionally substituted C1-C20 hydrocarbon group, optionally substituted C1-C20 alkoxy group or optionally substituted 5- to 7-membered heterocyclic group;
• and,
• n represents 0, 1, 2, 3 or 4),
• which comprises reacting a compound represented by the following formula (II):
• (wherein R1, R2 and R3 are the same as stated above;
• Z represents —O−M+ (wherein M represents Na, K or NEt3), oxo or hydroxy group;
• and the dotted line represents a chemical bond when Z is —O−M+ or hydroxy group) with a compound represented by the following formula (III):
• (wherein R4, R5 and n are the same as stated above;
• and Y represents —CNO) in the absence of a solvent or in a solvent inert to the reaction.