Suzuki coupling microwave-enhanced

Scheme 16 Microwave-enhanced Suzuki couplings and inhibitory activities of unsymmet-ric HIV-1 protease inhibitors...

A solventless Suzuki coupling reaction has been developed using both thermal and microwave enhancement. A potassium fluoride-alumina mixture is utilized along with palladium... 

Using a conventional dorm-room quality microwave oven, we have successfully performed Suzuki-Miyaura cross-coupling reactions catalyzed by Pd/C. Shorter reaction times are obtained (13 min of irradiation) using microwave irradiation compared to conventional methods of heating (> 1 h). Yields with relatively non-volatile aryl bromides range from 65 to 83%. Lower yields (15 - 27%) are obtained with relatively volatile aryl bromides substrates which may be evaporating during the course of the reaction. Ease of reaction set-up, rate enhancement from the microwave irradiation and facile work-up provided by the use of Pd/C makes this a very efficient procedure to mn. 

Villemin et al. (2001) studied the possibility of the Suzuki-Miyaura cross-coupling reaction of heteroaryl halides in monomethylformamide (MMF), which has a higher polarity than water and other amides under microwave irradiation. The commercially available nontoxic sodium tetraphenylborate has been used in water (or MMF) for the phenylation of heteroarylhalides under mono-mode microwave irradiation. The rate of reaction was enhanced and this afforded products in a more rapid and clean manner. 

---