The Suzuki homocoupling reaction under high-intensity ultrasound.
The Pd-catalysed Suzuki homocoupling of boronic acids was successfully carried out in water under high-intensity ultrasound (HIU). Heterogeneous catalysis with Pd/C, facilitating work up and purification, could be used without adding phosphine ligands. Reaction rates and yields were strongly influenced by the oxidant employed; excellent results were obtained using either molecular oxygen or 3-bromo-4-hydroxycoumarin. 3-Arylation of the latter with the Suzuki procedure had failed, exclusively affording the homocoupling products, symmetric biaryls. Besides offering a number of operational advantages, the use of HIU broadens the field of application for the Suzuki reaction.
Dipartimento di Scienza e Tecnologia del Farmaco, Università di Torino, Via Giuria 9, 10125 Torino, Italy. giancarlo.cravotto@unito.it
Giancarlo
G
Cravotto
Giovanni
G
Palmisano
Stefano
S
Tollari
Gian Mario
GM
Nano
Andrea
A
Penoni
D001897:Boronic Acids / Q000737:chemistry* / Q000528:radiation effects*; D003374:Coumarins / Q000737:chemistry* / Q000528:radiation effects*; D011829:Radiation Dosage; D013010:Sonication; D014867:Water / Q000737:chemistry*
D001897:Boronic Acids; D003374:Coumarins; D014867:Water