Reusable Cu_2O/PPh_3/TBAB System for the Cross-Couplings of Aryl Halides and Heteroaryl Halides with Terminal Alkynes

摘要

An efficient and reusable Cu_2O/PPh_3/TBAB (n-Bu_4NBr) system for the cross-coupling reactions of aryl and heteroaryl halides with terminal alkynes has been developed. Four types of Cu_2O, including bulky Cu_2O, cubic Cu_2O nanoparticles, octahedral Cu_2O nanoparticles, and spherical Cu_2O nanoparticles, were examined, and the octahedral Cu_2O nanoparticles were found to be the most effective catalyst for the reaction. In the presence of the octahedral Cu_2O nanoparticles, PPh_3, and TBAB, a variety of aryl and heteroaryl halides were reacted with alkynes including alkynols smoothly in moderate to good yields. Noteworthy is that the Cu_2O/ PPh_3/TBAB system can be recovered and reused several times without loss of any activities.