Nitroolefins are usually synthesized using the Henry reaction. Here we report an alternative metal-free decarboxylative nitration protocol for the preparation of the nitroolefins from α,β-unsaturated carboxylic acids using t-butylnitrite (t-BuONO) and TEMPO. α,β-Unsaturated carboxylic acids bearing β-aromatic and β-heteroaromatic substituents gave (E)-nitroolefins exclusively under mild conditions. A radical based pathway has been proposed for this decarboxylative nitration reaction.
硝基烯烃通常通过Henry反应合成。本文报道了一种无需
金属催化、通过脱羧硝化方法制备硝基烯烃的替代方案,该方法使用叔丁基
亚硝酸酯(t-BuONO)和
TEMPO作为试剂,从α,β-不饱和
羧酸制备硝基烯烃。在温和条件下,含有β-芳香和β-杂芳香取代基的α,β-不饱和
羧酸能够专一性地生成(E)-硝基烯烃。该脱羧硝化反应被认为遵循自由基反应途径。