suzuki homocoupling;
high-intensity ultrasound;
reaction in water;
biaryls;
oxygen;
3-bromo-4-hydroxycoumarin;
D O I:
10.1016/j.ultsonch.2004.05.005
中图分类号:
O42 [声学];
学科分类号:
070206 ;
082403 ;
摘要:
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. (C) 2004 Elsevier B.V. All rights reserved.