Abstract

The Knorr cyclization of β-ketoanilides to form 2-quinolones in the presence of acid is well documented chemistry. Double Knorr cyclization is rare, with very few examples appearing in the literature to date. The double Knorr methodology can provide access to tricyclic 1,8-diazaanthraquinones, a scaffold seen in the diazaquinomycin family. The optimized synthesis of diazaquinomycin A and structural analogues thereof via double Knorr cyclization of di-β-ketoanilide precursor substrates is reported. The scope and generality of the double Knorr cyclization were investigated along with an optimization study. The double Knorr cyclization was found to be sensitive to steric bulk on precursor substrates. In addition, the presence of a 5-hydroxy group on the 1,3-di-β-ketoanilide facilitated the double Knorr cyclization, possibly due to its stabilizing effect on the carbocation intermediates formed during the reaction.

The Knorr cyclization of β-ketoanilides to form 2-quinolones in the presence of acid is well documented chemistry. Double Knorr cyclization is rare, with very few examples appearing in the literature to date. The double Knorr methodology can provide access to tricyclic 1,8-diazaanthraquinones, a scaffold seen in the diazaquinomycin family. The optimized synthesis of diazaquinomycin A and structural analogues thereof via double Knorr cyclization of di-β-ketoanilide precursor substrates is reported. The scope and generality of the double Knorr cyclization were investigated along with an optimization study. The double Knorr cyclization was found to be sensitive to steric bulk on precursor substrates. In addition, the presence of a 5-hydroxy group on the 1,3-di-β-ketoanilide facilitated the double Knorr cyclization, possibly due to its stabilizing effect on the carbocation intermediates formed during the reaction.

中文翻译：

---

双重克诺尔环化的范围和优化：新型对称和不对称的三环1,8-二氮杂蒽醌的合成

摘要

在酸的存在下，β-酮基苯胺的克诺尔环化反应形成2-喹诺酮已被充分证明。双重克诺尔环化很少见，迄今为止在文献中很少出现。双重克诺尔方法可以提供三环1,8-二氮杂蒽醌（一种在二氮杂奎宁家族中发现的支架）的途径。报道了通过二-β-酮苯胺化物前体底物的双重克诺尔环化来最优化地合成二氮杂喹诺霉素A及其结构类似物。研究了双克诺尔环化的范围和一般性，并进行了优化研究。发现双重克诺尔环化对前体底物上的空间体积敏感。此外，在1,3-二-β-酮基苯胺上存在5-羟基有助于双克诺尔环化，

在酸的存在下，β-酮基苯胺的克诺尔环化反应形成2-喹诺酮已被充分证明。双重克诺尔环化很少见，迄今为止在文献中很少出现。双重克诺尔方法可以提供三环1,8-二氮杂蒽醌（一种在二氮杂奎宁家族中发现的支架）的途径。报道了通过二-β-酮苯胺化物前体底物的双重克诺尔环化来最优化地合成二氮杂喹诺霉素A及其结构类似物。研究了双克诺尔环化的范围和一般性，并进行了优化研究。发现双重克诺尔环化对前体底物上的空间体积敏感。此外，在1,3-二-β-酮基苯胺上存在5-羟基有助于双克诺尔环化，