Copper Mediated, Transmetallation Coupling Reactions using High Intensity Ultrasound

This dissertation summarizes research efforts focused on the use of boron and copper acetate to form new carbon-carbon and carbon-heteroatom bonds. Two new methods were developed using high intensity ultrasound as the reaction energy source. The first focused on the homocoupling of various aryl compounds using a commercially available polymer support. The use of this polymer support allows the reaction to proceed in an aqueous solvent system with only minimal preparation. The product yields were better than values reported in the literature using traditional reaction conditions and reaction times were decreased from 24-72 hours to 6 hours. The second method involved the application of ultrasound irradiation to the Chan-Evans-Lam reaction for the O-arylation of phenols, N-arylation of anilines and indoles, and S-arylation of thiols. The application of ultrasound to the Chan-Evans-Lam reaction decreased the reaction time from 72 hours to 4 hours while improving the product yield an average of 20% over reported results.

Reactions from both methods were expanded successfully from the millimole scale to the gram level while maintaining good product yields indicating potential applications in industrial processes. A mechanism study indicated that the two methods are related in that there was a similar transformation of the copper salt. Comparing these study results to literature reports suggests that the methods involve an oxidative addition / reduction elimination mechanism similar to the classic Ullmann reaction. The methodology of the research described herein can be characterized as atom efficient, scalable, environmentally friendly, inexpensive, and capable of rapidly producing high yields of the desired products.