Carbon dioxide was found as a selective agent to promote the palladium-catalyzed cyclotrimerization of alkynes in water. Both aryl and alkylacetylenes afforded the corresponding cyclotrimerization products regioselect...Carbon dioxide was found as a selective agent to promote the palladium-catalyzed cyclotrimerization of alkynes in water. Both aryl and alkylacetylenes afforded the corresponding cyclotrimerization products regioselectively in high yields using PdCl2, CuCl2, and CO2 as the catalytic system. However, tert-butylacetylene bearing a bulky group gave a dimerization product. Mechanism of this reaction was also discussed.展开更多
Carbon dioxide as both a selective agent and reaction media in the palladium-catalyzed Ullmann-type coupling has been described. The results showed that aryl chlorides could be easily activated in the presence of carb...Carbon dioxide as both a selective agent and reaction media in the palladium-catalyzed Ullmann-type coupling has been described. The results showed that aryl chlorides could be easily activated in the presence of carbon diox-ide and the chemoselectivity shifted toward the palladium-catalyzed Ullmann-type coupling reaction. In liquid car-bon dioxide, homocoupling reactions of aryl halides, including less reactive aryl chlorides, were carried out smoothly in moderate to good yields using Pd/C, zinc, and H2O as the catalytic system at room temperature.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 20202002) Hunan Province Education Department (No. 02C211) and Hunan Normal University (2001).
文摘Carbon dioxide was found as a selective agent to promote the palladium-catalyzed cyclotrimerization of alkynes in water. Both aryl and alkylacetylenes afforded the corresponding cyclotrimerization products regioselectively in high yields using PdCl2, CuCl2, and CO2 as the catalytic system. However, tert-butylacetylene bearing a bulky group gave a dimerization product. Mechanism of this reaction was also discussed.
基金the National Natural Science Foundation of China (No. 20202002), Hunan Province Department of Education (No. 02C211) and Hunan Normal University (2001).
文摘Carbon dioxide as both a selective agent and reaction media in the palladium-catalyzed Ullmann-type coupling has been described. The results showed that aryl chlorides could be easily activated in the presence of carbon diox-ide and the chemoselectivity shifted toward the palladium-catalyzed Ullmann-type coupling reaction. In liquid car-bon dioxide, homocoupling reactions of aryl halides, including less reactive aryl chlorides, were carried out smoothly in moderate to good yields using Pd/C, zinc, and H2O as the catalytic system at room temperature.
