Palladium-catalyzed Heck alkynylation of benzyl chlorides

An efficient and general protocol for the palladium-catalyzed Heck alkynylation of benzyl chlorides was developed. A catalyst system comprised of PdCl2(CH3CN)(2) and 2-dicyclohexyl-phosphino-2',4',6'-triisopropylbiphenyI (XPhos), with CS2CO3 as the base, efficiently couples a wide range of functionalized terminal alkynes and substituted benzyl chlorides at 65 degrees C. We have also demonstrated that the corresponding aryl allene product can be selected for using an excess amount of base and higher reaction temperatures (80 degrees C) in a one-pot procedure.