Sekar Pranesh Kavin, Rengan Ramesh, Sundarraman Balaji
Centre for Organometallic Chemistry, School of Chemistry, Bharathidasan University, Tiruchirappalli, Tamilnadu 620 024, India.
Department of Chemistry, Indian Institute of Technology, Guwahati, Assam 781039, India.
J Org Chem. 2024 Aug 16;89(16):11161-11172. doi: 10.1021/acs.joc.4c00621. Epub 2024 Jul 30.
A sustainable catalytic synthesis of selective monoalkylated amines from nitroarenes and alcohols by new palladium(II)-NNO pincer-type complexes has been described. Herein, a series of Pd(II) complexes [Pd(NNO)PPh] (-) are synthesized and characterized by analytical and spectroscopic (IR, NMR, and HR-MS) methods. The solid-state molecular structures of two complexes are established by X-ray single-crystal diffraction. Furthermore, the catalytic N-alkylation of challenging nitroarenes with primary and secondary alcohols has been performed by the well-defined palladium(II) complexes via borrowing hydrogen strategy. The current protocol offers a wide range of monoalkylated amines (26 examples) with a maximum yield of 87% utilizing 1 mol % of catalyst loading. Gratifyingly, the catalytic system works well under mild reaction conditions and atom economy with water is the only byproduct. Furthermore, control experiments confirm the formation of probable intermediates (aniline, aldehyde, and imine), and deuterium labeling authenticates the borrowing hydrogen mechanism. A gram-scale synthesis of an alkylated product clearly demonstrates the synthetic efficacy of the present catalytic methodology.
已报道了一种通过新型钯（II）-NNO钳型配合物从硝基芳烃和醇类可持续催化合成选择性单烷基化胺的方法。在此，合成了一系列钯（II）配合物Pd（NNO）PPh，并通过分析和光谱（红外、核磁共振和高分辨质谱）方法对其进行了表征。通过X射线单晶衍射确定了两种配合物的固态分子结构。此外，明确的钯（II）配合物通过借氢策略实现了具有挑战性的硝基芳烃与伯醇和仲醇的催化N-烷基化反应。当前方案以1 mol%的催化剂负载量提供了多种单烷基化胺（26个实例），最高产率为87%。令人欣慰的是，该催化体系在温和的反应条件下运行良好，原子经济性高，唯一的副产物是水。此外，对照实验证实了可能中间体（苯胺、醛和亚胺）的形成，氘标记验证了借氢机理。烷基化产物的克级合成清楚地证明了本催化方法的合成效果。
