Tandem synthesis of 3-halo-5-substituted isoxazoles from 1-copper(I) alkynes and dihaloformaldoximes
A tandem synthesis of 3-halo-5-substituted isoxazoles has been developed from 1-copper(I) alkynes and dihaloformaldoximes under base-free conditions. Thus, 1,3-dipolar cycloaddition and all its drawbacks can now be avoided completely.