Unexpected heterocyclization of electrophilic alkenes by tetranitromethane in the presence of triethylamine. Synthesis of 3-nitroisoxazoles.

Novel reaction of tetranitromethane (TNM) with electrophilic alkenes in the presence of triethylamine yielding substituted 3-nitroisoxazoles was found and studied. Triethylamine increases the reactivity of TNM toward electrophilic alkenes promoting their heterocyclization, and the reactions proceed in an unusual way. A variety of alpha,beta-unsaturated aldehydes, ketones, esters, amides, phosphonates, and nitro and sulfur compounds was involved in the heterocyclization reaction, and a wide range of functionalized 3-nitroisoxazoles was obtained in good to high yields. The scope and limitations of the reaction and the mechanistic aspects are discussed.