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 α-nitrocinnamates has been developed. Ethyl α-nitrocinnamates react smoothly with α-nitro carbonyl compounds to produce isoxazoles in good yields. Michael addition of pyridinium ylides to ethyl α-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.