Jinheng Li

Wacker reaction in supercritical carbon dioxide

It is reported for the first time that the Wacker reaction can nbe carried out smoothly in supercritical carbon dioxide or nROH/supercritical carbon dioxide. Results show that both scCO2 nand co-solvent can remarkably affect the selectivity towards methyl ketone nand the presence of ROH accelerates the reaction.The mechanism of the nWacker reaction in scCO2 is also discussed.

A novel and efficient synthesis of maleic anhydrides by palladium-catalyzed dicarbonylation of terminal acetylenes in H2O/dioxane

Abstract Maleic anhydrides can be obtained in high yields by the PdCl2-catalyzed dicarbonylation of terminal acetylenes in H2O/dioxane. It is not necessary to add reoxidants to the reaction, but reoxidants can affect the yield and the rate. We also found that the rate decreased and only traces of maleic anhydrides were formed in the presence of KCl or LiCl.

Use of water as a direct hydrogen donor in supercritical carbon dioxide: a novel and efficient Zn–H2O–CO2 system for selective reduction of aldehydes to alcohols

This is the first report that nZn–H2O–CO2 is an excellent reducing nreagent for the reduction of aldehydes in supercritical carbon dioxide n(scCO2). The corresponding alcohols were obtained in good yields nand excellent selectivity. The experimental results showed that nscCO2 plays an important role in this reduction.

Solvent‐Free, Palladium‐Catalyzed Suzuki–Miyaura Cross‐Couplings of Aryl Chlorides with Arylboronic Acids

Abstract Pd(MeCN)2Cl2/PCy3 was found to be an efficient catalytic system for the Suzuki–Miyaura cross‐couplings of aryl chlorides with arylboronic acids under solvent‐free conditions. Furthermore, the presence of the conventional solvents had deleterious effect on the reaction. In the presence of Pd(MeCN)2Cl2, PCy3, and TBAF (tetra‐n‐butylammonium fluoride), a number of aryl chlorides including heteroaryl chlorides were coupled with arylboronic acids or heteroarylboronic acids smoothly to afford the corresponding products in moderate to excellent yields.

PALLADIUM-CATALYZED CARBONYLATION OF TERMINAL ACETYLENES: A NEW METHOD FOR SYNTHESIS OF ACETYLENECARBOXYLATES

Acetylenecarboxylates were easily prepared via palladium bromide-catalyzed carbonylation of terminal acetylenes in fair to good yields.

Palladium-catalyzed Ullmann-type coupling with zinc in the presence of H2O in liquid carbon dioxide

Carbon dioxide was used not only as a reaction medium but also as a reagent to activate ArCl in the palladium-catalyzed Ullmann-type coupling. In liquid carbon dioxide not only various aromatic iodides and bromides but also aromatic chlorides, non-reactivated substrates in earlier reports, were coupled in moderate to good yields in the presence of Pd/C, zinc and H2O at room temperature overnight.

Respective conversion of n-butylamine to methyl N-n-butylcarbamate and oxalbutyline in supercritical carbon dioxide

O2 and the solvent (MeOH–supercritical carbon ndioxide) can control the chemoselectivity of the palladium-catalyzed ncarbonylation of amines; methyl N-n-butylcarbamate or oxalbutyline ncould be obtained in high yields upon varying the conditions.

Palladium(II)-catalyzed oxidation of acrylate esters to acetals in supercritical carbon dioxide

The development of a new palladium(II)-catalyzed oxidation of methyl acrylate, affording methyl 3,3-dimethoxypropanoate in excellent conversion and selectivity in supercritical CO2, is presented.

New role of carbon dioxide in Lewis assisted Brönsted acid accelerated diiodination of alkynes in water

CO2 is reported here as a Lewis assisted Bronsted acid accelerator to promote diiodination of alkynes. In the presence of CO2, quantitative yields of trans-1,2-diiodoalkenes were obtained by diiodination of both electron-rich and electron-deficient alkynes with I2 in H2O.

A Novel Stereoselective Synthesis of Maleate Derivatives via Palladium-Catalyzed Dicarboalkoxylation of Terminal Alkynes

Abstract Alkynes were dicarboalkoxylated efficiently and stereoselectively in high yields reacting for about 2h under atmospheric pressure of carbon monoxide at room temperature using a catalytic amount of PdCl2, and a stoichiometric amount of CuCl2.