Thiols copper-catalyzed coupling with aryl

Copper-Catalyzed Coupling of Aryl Halides with Alcohols and Thiols... 

Some of the advantages of copper catalysts are that they are inexpensive, abundant etc. In 2013, Fu, Peters and their co-workers reported a copper-catalyzed coupling of aryl halides with thiols via a single-electron transfer pathway. In order to prove the reaction mechanism, they performed the reaction of allyl-o-iodophenol with thiophenol as well. No cyclized product could be produced when the reactions were performed in the dark, while 57% of dihydrobenzofuran was formed when hv was introduced (Scheme 2.40). 

A common feature of the above described processes is that only aryl substituents are tolerated on the side of the acid chloride 4 and aryl iodide 6 due to ketene formation and jd-H elimination from aliphatic derivatives. However, primary alkyl-substituted alkynones 1 can be obtained by a palladium-catalyzed cross-coupling of corresponding thiol-esters 9 with terminal alkynes 5 in the presence of overstoichiometric amounts of copper (2003SL1512, 2010SL1239) (Scheme 4). 

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