A Palladium-Catalyzed Aqueous Suzuki Cross-Coupling Reaction Without Additional Ligands

Abstract

The invention discloses a palladium-catalyzed water-phase Suzuki cross-coupling reaction without external ligands. Palladium is used as a catalytic species, water is used as a solvent, and a quaternary ammonium base and an emulsifier are used to perform a highly efficient palladium-catalyzed carbon-carbon bond cross-coupling reaction. Synthesis of biaryl hydrocarbons. The reaction system of the invention is green, the reaction conditions are mild, and the catalysis can be completed in 3 minutes at a relatively high temperature, which provides the possibility for catalysis on a fluid bed. And the catalyst has no external ligands. Compared with the traditional inorganic base, the quaternary ammonium base can stabilize the catalytic species palladium to a certain extent, reduce the amount of palladium, and can be directly reused in the recycling process without significantly reducing It can be reused more than 8 times under the premise of activity. The catalytic product can be crystallized directly in the system, and the pure product can be obtained by filtering and washing, which saves the step of column chromatography, and the operation is simple and safe. In addition, the reaction system has good universality for reaction substrates and has great practical application value.

Description

technical field [0001] The invention belongs to the technical field of organic synthesis, and specifically relates to a simple, efficient and green palladium-catalyzed water-phase Suzuki cross-coupling reaction without external ligands. Background technique [0002] Transition metal palladium-catalyzed Suzuki cross-coupling reaction of aryl boronic acid compounds and halogenated aromatic hydrocarbons is an effective method to construct carbon-carbon bonds, and has been widely used in the synthesis of natural products, drugs, advanced functional materials and fine chemical intermediates . At present, what is mainly used in industry is the palladium complex obtained under the situation of adding organic ligands (such as triphenylphosphine, etc.) as a homogeneous catalyst, with traditional organic solvents as the reaction medium, and the entire catalytic process usually requires nitrogen or The argon atmosphere is used for protection, the operation process is cumbersome, and i...

AI Technical Summary

Problems solved by technology

At present, what is mainly used in industry is the palladium complex obtained under the situation of adding organic ligands (such as triphenylphosphine, etc.) as a homogeneous catalyst, using traditional organic solvents as the reaction medium, and the entire catalytic process usually requires nitrogen or Protected by argon atmosphere, the operation process is cumbersome, and it will pollute the environment

In recent years, more and more attention has been paid to green chemistry. As an ideal reaction medium, water has the advantages of abundant resources, cheap and easy to obtain, non-toxic, and non-polluting. There have been many reports on the Suzuki reaction system using water as the medium. However, most reaction systems need to add water-soluble ligands to promote the reaction. The synthesis steps of most ligands are relatively complicated and expensive, and the separation of the ligands after the reaction is also time-consuming and laborious. In order to avoid the catalytic species palladium in the reaction Inactivation due to agglomeration during the process, and the demand for palladium is relatively large, which limits the scope of application

Moreover, whether it is in a homogeneous catalysis or a heterogeneous catalysis system, the separation and purification of products requires the use of column chromatography, which is cumbersome to operate, and petroleum ether, silica gel, etc. are required in the process of product separation and purification, which is highly toxic and expensive.

In addition, traditional product separation and purification methods make it difficult to reuse the catalytic system, increasing the pressure of sewage discharge and consumption costs

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