Iridium-catalyzed Acceptorless Dehydrogenative Coupling Of Arylhydrazines And Alcohols For The Synthesis Of Arylhydrazones

Arylhydrazones derivatives are an important class of nitrogen-containing heterocyclic compounds, because it is contain lively unsaturated C=N double bond of the imine compounds that can happen a variety of reaction to synthesis of indole, carbazole, pyrazole, indazole heterocyclic compounds, so arylhydrazones is also an important intermediate of synthesis of heterocyclic compounds, they exhibit remarkable broad application in medicine, pesticide, organic synthesis, natural products and industrial synthesis. The structure of aromatic hydrazone existed widely in physiological and pharmacological activity of compounds and natural products, and of the indispensable substances that constitute some organisms and life activities, for example, some of them as inhibitors of macrophage migration inhibitory factor (MIF), trypanosomatid parasites antagonists, monoamine oxidase (MAO) inhibitors, protein tyrosine phosphatase-2 (Shp2) inhibitors, and potent antimalarial agents.The traditional method for the synthesis of aromatic hydrazone compounds involves the condensation reaction of aromatic hydrazine or its salt with aldehydes or ketones, however, the reaction process of these reactions are usually some deficiencies:materials aldenhydes or ketons with great toxicity and easy metamorphism should not be stored, reaction of low atomic economy, environmental pollution, toxic by-products generated catalyst load is larg and expensive and limited the scope of substrates. The team to explore and implement the use of transition metal catalysts [Cp*IrCl2]2 (Cp*=pentamethylclopentadienyl) catalytic acceptorless dehydrogenative coupling of arylhydrazines and alcohols for the direct synthesis of arylhydrazones, the most important thing is that the high selectivity of reaction, in the course of the reaction completely into the target product, and no N-alkylation and other by-products. This method uses less convenient and accessible, catalyst load catalysts, reaction results high selectivity and stability of product is strong, high atomic economy reaction process and the by-products of hydrogen gas and water pollution to the environment. In addition, the method of the substrate scope is widespread, including aromatic hydrazine, aromatic primary alcohol, aromatic secondary alcohol, fatty alcohols.In the second chapter, the 1-methyl-1-phenylhydrazine and benzyl alcohol was selected as a model to explore the feasibility of reaction, the catalytic systems was finally determined [Cp*IrCl2]2/KOH, implements the catalytic activation of alcohol as electrophilic reagent to synthesis of arylhydrazones derivatives, and the reaction mechanism of experiments that were tested. It is important to emphasize that the reaction system has many obvious advantages: simple materials accessible, catalytic results high selectivity, high atom economy and green, pollution-free.This study mainly discuss a class of new homogeneous catalytic system for the low load, using low-toxic raw material synthesis of aromatic hydrazone compounds, at the same time production of byproduct of no damage to the environment, open the alcohol as electrophilic reagents in organic synthesis research scope, and also promote the green chemistry guide the development of green organic synthesis reaction, and further expanded the aromatic hydrazone synthetic research field.