Iodoarenes alkyne coupling

Cul as cocatalyst seems to be necessary for the conversion of dibromoarenes into the corresponding alkynylated products, but Linstrumelle demonstrated that if iodoarenes are coupled in the presence of a suitable amine, Cul can be omitted. The presence of Cul however does not seem to harm the progress of the reaction, and insofar it can always be added. Its proposed role is the formation of a copper(I) o- or jT-acetylide to activate the alkyne toward transmeta-lation. The matter has been discussed thoroughly by Osakada and Yamamoto. ... 

Ethynyl-3-pyridinols undergo coupling with iodoarenes, aryl triflates, and enol triflates in the presence of PdCl2(PPh3)2 and Cul. Nucleophilic attack of oxygen onto the arylated alkyne product occurs in situ to give... 

Dienes Consecutive reactions of alkynes with CpjZr (from CpjZrClj and BuLi) and allyl trimethylsilyl ether generate (l,4-dien-l-yl)zirconocene derivatives which can be used to couple with iodoarenes under Pd(0)-Cu(I) catalysis. 

In 2006, Dupont s group tilso reported a simple and efficient copper-free catalytic system based on some ptJladacycle cattilysts (Figure 1.31) [109]. The coupling of iodoarenes and activated bro-moarenes could be conducted with terminal alkynes at room temperature. The yields were generally good and TONs of up to 100 000 could be obtained with iodoarene substrates (Figure 1.31). 

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