- 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.
- Zhao, Zhongkui,Li, Renzhi,Li, Yu,Wang, Guiru
-
-
Read Online
- Highly efficient and clean synthesis of 1-amino-2-acetylanthraquinone by copper-catalyzed reductive cleavage of isoxazole motif
-
A clean and highly efficient synthesis of 1-amino-2-acetylanthraquinone via reductive isoxazole ring cleavage of 3-methylanthra[1,2-c]isoxazole-6,11-dione catalyzed by trace copper using hydrazine hydrate as a clean reducing agent and water as a green reaction medium under mild reaction conditions was investigated. Various transition-metal catalysts were screened for the reductive ring-opening reaction, and Cu(NO3)2 was shown to be an excellent catalyst. A conversion of 97.2% and 1-amino-2-acetylanthraquinone selectivity greater than 95% were obtained in the presence of 2.6 mol% Cu(NO3)2 (turnover number 38) with 1.3 equiv. of hydrazine hydrate for 2 h in water. The structure of the product was confirmed by 1H nuclear magnetic resonance spectroscopy and mass spectrometry; the main byproduct was hydroxyl-substituted 1-amino-2-acetylanthraquinone. A possible reaction mechanism for the copper-catalyzed ring cleavage of 3-methylanthra[1,2-c]isoxazole-6,11-dione with hydrazine hydrate was proposed.
- Zhao, Zhongkui,Li, Renzhi,Li, Yu
-
-
Read Online