Palladium Nanoparticle-Catalyzed Direct Ethynylation of Aliphatic Carboxylic Acid Derivatives via C(sp3)-H Bond Functionalization

We have developed a sulfur-modified, gold-supported palladium material (SAuPd) with palladium, Pd, nanoparticles on its surface; it is a recyclable, low-leaching Pd catalyst. Here we report, using SAuPd, the first example of Pd nanoparticle-catalyzed, unactivated C(sp(3))H bond functionalization of amides, using 8-aminoquinoline as a directing group, to yield ethynylated products. The low leaching properties of SAuPd enabled it to be recycled and reused 10 times for C(sp(3))H bond functionalization.