CoCl2 为催化剂，苯甲醇和苯胺衍生物脱氢偶联，微波辅助合成 E-醛亚胺、N-杂环和 H2,The Journal of Organic Chemistry

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CoCl2 为催化剂，苯甲醇和苯胺衍生物脱氢偶联，微波辅助合成 E-醛亚胺、N-杂环和 H2
The Journal of Organic Chemistry ( IF 3.3 ) Pub Date : 2023-06-09 , DOI: 10.1021/acs.joc.3c00682
Adwitiya Pal ₁ , Krishna Mohan Das ₁ , Arunabha Thakur ₁

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醇与胺之间的无受体脱氢偶联（ADC）生产亚胺主要是通过使用贵金属基配合物或地球丰富的金属离子与敏感且复杂的配体体系的配合物作为催化剂来实现的，并且大多在恶劣的反应条件下实现。尚未探索使用容易获得的地球丰富的金属盐作为催化剂而不需要配体、氧化剂或任何外部添加剂的方法。我们报道了前所未有的微波辅助CoCl ₂催化苯甲醇和胺的无受体脱氢偶联，用于合成E-醛亚胺、N-杂环和H ₂条件温和，无需任何复杂的外源配体模板、氧化剂或其他添加剂。这种环境友好的方法表现出广泛的底物范围（43 种，包括 7 种新产品），并且苯胺环上的官能团具有良好的耐受性。通过气相色谱(GC)和HRMS检测金属相关中间体、通过GC检测H _{2以及动力学同位素效应揭示了该CoCl}₂催化反应的机制是通过ADC。此外，动力学实验和哈米特分析对苯胺环上取代基性质的变化揭示了对不同取代基反应机理的洞察。

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Microwave-Assisted Synthesis of E-Aldimines, N-Heterocycles, and H2 by Dehydrogenative Coupling of Benzyl Alcohol and Aniline Derivatives Using CoCl2 as a Catalyst

The acceptorless dehydrogenative coupling (ADC) between alcohols and amines to produce imines has been achieved mostly by employing precious-metal-based complexes or complexes of earth-abundant metal ions with sensitive and complicated ligand systems as catalysts mostly under harsh reaction conditions. Methodologies using readily available earth-abundant metal salts as catalysts without the requirement of ligand, oxidant, or any external additives are not explored. We report an unprecedented microwave-assisted CoCl₂-catalyzed acceptorless dehydrogenative coupling of benzyl alcohol and amine for the synthesis of E-aldimines, N-heterocycles, and H₂ under mild condition, without any complicated exogenous ligand template, oxidant, or other additives. This environmentally benign methodology exhibits broad substrate scope (43 including 7 new products) with fair functional-group tolerance on the aniline ring. Detection of metal-associated intermediate by gas chromatography (GC) and HRMS, H₂ detection by GC, and kinetic isotope effect reveal the mechanism of this CoCl_2-catalyzed reaction to be via ADC. Furthermore, kinetic experiments and Hammett analysis with variation in the nature of substituents over the aniline ring reveal the insight into the reaction mechanism with different substituents.

更新日期：2023-06-09

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