钯催化超临界CO_2中合成四取代烯烃

在超临界CO2中,钯作为催化剂,CsOAc作为碱,用易得的芳基碘、内炔、芳基硼酸三组分偶联高产率地一步合成四取代烯烃。超临界CO2中三组分偶联的最后优化条件是在100℃、PCO2=7.5 MPa下,芳基碘（0.5 mmol）,内炔（0.25 mmol）,芳基硼酸（0.5 mmol）,PdCl2（2 mol%）和CsOAc（1 mmol）反应24 h。超临界二氧化碳作为溶剂优化了这个钯催化体系并且大大的提高了目标产物四取代烯烃的产率。此方法是内炔的全顺式加成,且超临界体系是一个对环境友好的高效体系。

Palladium-Catalyzed Synthesis of Tetrasubstituted Olefins in Supercritical Carbon Dioxide

The Pd-catalyzed three-component coupling of readily available aryl iodides,internal alkynes,and arylboronic acids provides a convenient,one-step route to tetrasubstituted olefins in good to excellent yields in scCO2 using CsOAc as base.The final optimized reaction conditions for the three-component coupling in scCO2 was determined to be aryl iodides(0.5 mmol),internal alkynes(0.25 mmol),and arylboronic acids(0.5 mmol) in the presence of PdCl2(2 mol%) and CsOAc(0.75 mmol) in scCO2(PCO2= 7.5 MPa) at 100 ℃ for 24 h.The presence of scCO2 generally substantially improved the Pd-catalyzed system and increased the yields of the desired tetrasubstituted olefins.The reaction involved full cis-addition of internal alkynes and the system in scCO2 was an effective and environmental friendly alternative to the previous methods involving organic solvent.