Phosphorus coupling products, aryl halide

Biaryl formation using Stille coupling suffers from the problem of by-product formation, which is apparently due to ligand exchange between palladium and phosphorus subsequent to oxidative addition of the aryl halide to palladium (Scheme 4-35). A detailed paper dealing with this phenomenon has appeared [128]. In unfavorable cases the required biaryl can be the minor product. 

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