Synthesis of 5‐Fluoro‐ and 5‐Bromoalkylisoxazoles via Nitrosation of 1,1‐Dihalocyclopropanes with Sulfur Trioxide Activated Nitrosyl Chloride.

Abstract A method for the synthesis of 5-fluoro- and 5-bromoalkylisoxazoles via nitrosation of alkylated gem -dihalocyclopropanes with a nitrosyl chloride sulfur trioxide adduct has been developed. In the case of bromofluorocyclopropanes the reaction proceeded with excellent chemoselectivity thus providing exclusively 5-fluoroisoxazoles.