Simple primary amine catalyzed aerobic reductive ring-cleavage of isoxazole motif

A clean and highly efficient catalytic aerobic reductive ring-cleavage of 3–methylanthra[1,2-c]isoxazole-6,11-dione to 1-amino-2-acetylanthraquinone was performed using simple organic amines as organocatalysts and water as a green reaction medium. This method provides a new clean transformation of isoxazole-containing compounds to the corresponding ortho-amino ketones. The catalytic performance of various organic amines was carefully screened, and simple organic primary amines were found to be promising practical catalysts with outstanding catalytic performance. Isopropylamine as the organocatalyst gave 97.2% conversion of 3–methylanthra[1,2-c]isoxazole-6,11-dione, with 97.2% selectivity to 1-amino-2–acetylanthraquinone, in the presence of oxygen only, using 1 equiv. of hydrazine hydrate at room temperature for 3 h. A possible mechanism is also proposed.

Graphical AbstractA simple organic-primary-amine-catalyzed aerobic reductive isoxazole ring-cleavage strategy for clean and highly efficient 1-amino-2-acetylanthraquinone production was described.Figure optionsDownload full-size imageDownload as PowerPoint slide