Abstract 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.

中文翻译：

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通过铜催化异恶唑基序的还原裂解高效清洁合成 1-氨基-2-乙酰蒽醌

摘要 以水合肼为清洁还原剂，通过痕量铜催化 3-甲基蒽[1,2-c]异恶唑-6,11-二酮的还原异恶唑环裂解，清洁高效合成 1-氨基-2-乙酰蒽醌并在温和的反应条件下研究了水作为绿色反应介质。为还原开环反应筛选了各种过渡金属催化剂，结果表明 Cu(NO3)2 是一种极好的催化剂。在 2.6 mol% Cu(NO3)2（周转数 38）和 1.3 当量的存在下，获得了 97.2% 的转化率和大于 95% 的 1-氨基-2-乙酰蒽醌选择性。水合肼在水中 2 小时。产物结构经1H核磁共振波谱和质谱确证；主要副产品是羟基取代的 1-氨基-2-乙酰蒽醌。提出了铜催化 3-甲基蒽[1,2-c]异恶唑-6,11-二酮与水合肼开环的可能反应机理。