A General Palladium-Catalyzed Hiyama Cross-Coupling Reaction of Aryl and Heteroaryl Chlorides

KGaA, Weinheim. A general palladium-catalyzed Hiyama cross-coupling reaction of aryl and heteroaryl chlorides with aryl and heteroaryl trialkoxysilanes by a Pd(OAc)2/L2 catalytic system is presented. A newly developed water addition protocol can dramatically improve the product yields. The conjugation of the Pd/L2 system and the water addition protocol can efficiently catalyze a broad range of electron-rich, -neutral, -deficient, and sterically hindered aryl chlorides and heteroaryl chlorides with excellent yields within three hours and the catalyst loading can be down to 0.05 mol % Pd for the first time. Hiyama coupling of heteroaryl chlorides with heteroaryl silanes is also reported for the first time. The reaction can be easily scaled up 200 times (100 mmol) without any degasification and purification of reactants; this facilitates the practical application in routine synthesis.