The impact of water, catechol, and hexafluoroantimonic acid co-catalyts on palladium(II) catalyzed hydroarylation of acetylene

Hydroarylation of alkynes has been a reaction of high interest in the field of homogenous catalysis because this process creates a new carbon-carbon bond by direct addition of an arene and an alkyne. This type of reaction is beneficial in synthesis of pharmaceuticals and natural products since it can shorten a multi-step synthetic path. The challenge of this research is to improve the efficiency of the reaction. Previous studies have proven palladium(II) complex catalyst [Pd(PNP)(C2H4)](SbF6)2 and water as co-catalyst as a useful catalytic system. The main goal of this thesis is to increase the TON to more than 100 for the addition of pentamethylbenzene to acetylene as hydroarylation test reaction. First, the standard protocol using 3 equiv of water/ PdII catalyst was re-tested for reproducibility purpose studying the substrate : catalyst ratios of 50:1, 100:1, 150:1, and 200:1. Due to the limits of water, hexafluoroantimonic acid and catechol were studied as alternative co-catalysts. Using ~10 equiv of HSbF6/ PdII catalyst acetylene polymerization was strongly promoted. Catechol was studied using 1, 3, 6 and 9 equiv/ PdII catalyst and showed higher efficiency than water as proton shuttle. The conversion of the reactions was determined by 1H NMR spectroscopy