The use N‐sulfonyl‐protected hydroxylamines as bi‐nucleophiles in iron‐catalyzed propargylic substitutions allows the selective one‐potsynthesis of four classes of substituted isoxazoles or isoxazolines from the same propargylic alcohols (21 examples) by simply tuning the nature of the base. By using an iron(III) catalyst and a base such as triethylamine (3 equiv), isoxazoles 3 are obtained in good