Chemoselective Reduction of Functionalized 5-Nitroisoxazoles: Synthesis of 5-Amino- and 5-[Hydroxy(tetrahydrofuran-2-yl)amino]isoxazoles
摘要:
Reduction by using SnCl2 of easily accessible 5-nitroisoxazoles substituted with an electron-withdrawing group (EWG) has been studied. Whereas the reaction in ethanol yielded 5-aminoisoxazoles, performing the reaction in tetrahydrofuran gave previously unknown 5-[hydroxy(tetrahydrofuran-2-yl)amino]isoxazoles. Both reduction procedures were optimized to afford the corresponding products in good to excellent yields. Some mechanistic details concerning the inclusion of the tetrahydrofuranyl moiety into the reaction product are discussed
Unexpected Heterocyclization of Electrophilic Alkenes by Tetranitromethane in the Presence of Triethylamine. Synthesis of 5-Nitroisoxazoles
作者:Yulia A. Volkova、Elena B. Averina、Dmitry A. Vasilenko、Kseniya N. Sedenkova、Yuri K. Grishin、Per Bruheim、Tamara S. Kuznetsova、Nikolai S. Zefirov
DOI:10.1021/acs.joc.8b03086
日期:2019.3.15
A novel reaction of tetranitromethane with electrophilic alkenes in the presence of triethylamine affording substituted 5-nitroisoxazoles is described. Triethylamine reacts with tetranitromethane to generate N-nitrotriethylammonium and trinitromethanide. This process provides the heterocyclization of electrophilic alkenes. A variety of α,β-unsaturated aldehydes, ketones, esters, amides, phosphonates
Reduction by using SnCl2 of easily accessible 5-nitroisoxazoles substituted with an electron-withdrawing group (EWG) has been studied. Whereas the reaction in ethanol yielded 5-aminoisoxazoles, performing the reaction in tetrahydrofuran gave previously unknown 5-[hydroxy(tetrahydrofuran-2-yl)amino]isoxazoles. Both reduction procedures were optimized to afford the corresponding products in good to excellent yields. Some mechanistic details concerning the inclusion of the tetrahydrofuranyl moiety into the reaction product are discussed