An expeditious aqueous Suzuki-Miyaura method for the substituted aryl heterocyclics

Palladium-catalyzed cross-coupling reactions utilizing aryl halides have become a widely used strategy for the formation of new carbon-carbon bonds and in particular for the synthesis of biaryls. The replacement of expensive, toxic, and flammable organic solvents by water is highly desirable for reducing costs and for developing environmentally benign synthetic reactions that facilitate catalyst recycling. Herein, we report an efficient Suzuki-Miyaura cross-coupling reaction using a variety of heterocyclic halides in neat water. Employing air- and moisture-stable palladium-phosphinous acid catalyst [(t-Bu)2P(OH)]2PdCl2(POPd) allows formation of substituted aryl heterocyclics in moderate to high yields. The organic cosolvents are not required. The feasibility of catalyst recycling has also been demonstrated.