Although the selective conversion of cyclohexanone oximes to primary anilines would be a good complement to the classical synthetic methods for primary anilines, which utilize arenes as the starting materials, there have been no general and efficient methods for the conversion of cyclohexanone oximes to primary anilines until now. In this study, we have successfully realized the efficient conversion of cyclohexanone oximes to primary anilines by utilizing a Mg–Al layered double hydroxide supported Pd catalyst (Pd(OH)_x/LDH) under ligand-, additive-, and hydrogen-acceptor-free conditions. The substrate scope was very broad with respect to both cyclohexanone oximes and cyclohexenone oximes, which gave the corresponding primary anilines in high yields with high selectivities (17 examples, 75% to >99% yields). The reaction could be scaled up (gram-scale) with a reduced amount of the catalyst (0.2 mol %). Furthermore, the one-pot synthesis of primary anilines directly from cyclohexanones and hydroxylamine was also successful (five examples, 66–99% yields). The catalysis was intrinsically heterogeneous, and the catalyst could be reused for the conversion of cyclohexanone oxime to aniline at least five times with keeping its high catalytic performance. Kinetic studies and several control experiments showed that the high activity and selectivity of the present catalyst system were attributed to the concerted catalysis of the basic LDH support and the active Pd species on LDH. The present transformation of cyclohexanone oximes to primary anilines proceeds through a dehydration/dehydrogenation sequence, and herein the plausible reaction mechanism is proposed on the basis of several pieces of experimental evidence.

中文翻译：

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Mg-Al层状双氢氧化物负载钯催化剂的协同催化选择性从环己酮肟合成伯胺

尽管将环己酮肟选择性转化为伯氨基苯胺是对经典合成苯胺的传统方法的很好的补充，后者使用芳烃作为起始原料，但一直没有通用有效的方法将环己酮肟转化为伯苯胺。现在。在这项研究中，我们已经成功地实现了利用Mg-Al层状双氢氧化物负载的Pd催化剂（Pd（OH）_x/ LDH）在无配体，无添加剂和无氢的条件下进行。相对于环己酮肟和环己烯酮肟而言，底物范围非常广泛，以高收率和高选择性提供了相应的伯苯胺（17个实例，收率75％至> 99％）。可以用减少量的催化剂（0.2mol％）扩大反应规模（克规模）。此外，直接从环己酮和羟胺一锅法合成伯苯胺也很成功（五个例子，产率为66-99％）。该催化剂本质上是非均相的，并且该催化剂可以重复使用至少五次以保持其高催化性能而将环己酮肟转化为苯胺。动力学研究和一些对照实验表明，本催化剂体系的高活性和选择性归因于碱性LDH载体和LDH上活性Pd物种的协同催化作用。环己酮肟向伯苯胺的当前转化通过脱水/脱氢序列进行，并且在此基于若干实验证据提出了合理的反应机理。