Concise Synthesis of Phosphonylated Heteroarenes from NitroHeteroarenes by Dearomatization/Elimination

Abstract

Aromatic organophosphorus compounds have significant applications in catalysis, organic synthesis, me-dicinal chemistry, and materials science. Herein, we report a metal-free, Et3Nmediated phosphorylation of 4-nitroisoxazoles with secondary phosphine oxides. The protocol proceeds via a unique dearomatization-elimination process, affording functionalized phosphonylated isoxazoles with good yields under mild conditions. Furthermore, some other aromatic substrates, including nitrofuran, nitroindole, nitrothio-phene and nitroquinoxaline derivatives can also undergo this reaction to afford corresponding phospho-nylated heteroarenes.Gram-scaled synthesis and synthetic transformations further suggest that this methodology has practical applicability and synthetic value. Additionally, we successfully synthesized novel phosphonylated enaminones via a one-pot cascade dearomatization/elimination/reductive ringopening process.