Reactions with Aryl Chlorides and Other Organic Electrophiles

Reactions with Aryl Chlorides and Other Organic Electrophiles 

One of the challenges in the Suzuki-type cross-coupling is to extend this reaction from electron-rich aryl iodides, bromides, and triflates to less reactive aryl sulfonates and aryl chlorides, which show poor reactivity in terms of oxidative addition in the catalytic cycle. Aryl mesylates, benzenesulfonates, and tosylates are much less expensive than triflates, and are unreactive toward palladium catalysts. The Ni(0)-catalyzed Suzuki-type cross-coupling reaction of aryl sulfonates, including mesylates, with arylboronic acids in the presence of K3P04 has been reported [123]. 

One limitation in the scope of the Suzuki reaction has been its inefficiency when aryl chlorides are employed as substrates, although there have been several accounts of the coupling of electron-poor aryl chlorides [124]. 

Most recently, Fu and co-workers [126] have reported that the use of Pd2(dba)3/PtBu3 as a catalyst for a wide range of aryl and vinyl halides, including chlorides, facilitates their Suzuki cross-coupling with arylboronic acids, giving the coupled products in very good yield, typi- 

Aryl Chloride Boronic Acid Product Temp. ( C) Yield (%) 

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