Synthesis of 3-Substituted Isoxazolecarboxamides as Potential Fungicides

A series of new 3-substituted isoxazolecarboxamides have been prepared from aldehydes. A key step was a 1,3-dipolar cycloaddition of nitrile oxides to α,β-unsaturated esters. Some of these compounds exhibited high fungicidal activities against Alternaria alternate, Botrytis cinerea, Rhizoctonia solani, Fusarium culmorum, and Phytophthora cactorum.