One-Step Synthesis 3-Nitroisoxazoles

Significance

Reported is a general method for the synthesis of 3-nitroisoxazoles by reacting activated (Et₃N) tetranitromethane with various α,β-unsaturated compounds containing an electron-withdrawing group. Thus, α,β-unsaturated ketones, aldehydes, carboxylic acid esters, amides, and nitroalkenes were all successfully reacted to form the corresponding substituted 3-nitroisoxazoles. The substrate scope was well studied and the yields range from poor to good. The least ­succesful reaction was that with acrylic amides, which in six out of seven examples led to mixtures of isoxazole and Michael addition products (A and B, respectively).