Ethyl α-Nitrocinnamates in the Synthesis of Highly Functionalized Isoxazoles

An effective method for the synthesis of highly functionalized isoxazoles from readily available starting ethyl u-nitrocinnamates has been developed. Ethyl u-nitrocinnamates react smoothly with alpha-nitro carbonyl compounds to produce isoxazoles in good yields. Michael addition of pyridinium ylides to ethyl alpha-nitrocinnamates can also produce these isoxazoles effectively. These pyridinium salts can be generated in situ from the corresponding alkyl bromides. The one-pot multicomponent process was also developed. Isoxazoles can be produced directly from readily available aromatic aldehydes, ethyl nitroacetate, and pyridinium salts.