Abstract
Palladium cross couplings are some of the most important reactions in medicinal chemistry today. The catalyst’s ability to make complex C-C bonds has made it a vital part of modern-day chemistry. Since palladium-catalysed reactions have become vital to the field it is naturalthat research on finding mild, safe, and effective palladium reactions has become a topic ofinterest in modern day chemistry. Other palladium ligands such as neutral bidentate ligandshave been researched and many protocols have appeared over the years but most of theseprotocols require harsher reaction environments or need expensive reaction materials like theones in Larock’s protocols. The reaction in this project is mild and cheap in comparison. The aim of this project is to test three novel anionic palladium ligands computationally and experimentally in the model decarboxylative reaction using 2,6-dimethoxybenzoic acid andacetonitrile as reactants to make 2,6-dimethoxyacetophenone. The purpose was to investigate how the anionic ligands compared to the existing bidentate ligand used in the same reaction.The computational results show that the calculated energy barriers were around 46-60 kJ mol-1 depending on the ligand and configuration calculated. This meant that the ligands have reasonable energy barriers for the nitrile insertion step indicating that the ligands are not being rejected by the calculations and are potential ligands for the reaction. Experimental synthesis results show that ligand 1 (6-methylpicolinic acid) and ligand 3 (6-methyl-N-(methylsulfonyl)-2-pyridinecarboxamide) were comparable to the reference ligand(6-methyl-2,2’-bipyridine). This was the case in different reaction conditions in the form ofchanges in temperature and solvent content ratio. Ligand 2 (6-methylpyridine-2-sulfonic acid)was also synthesized but not tested experimentally. The yield of the model reaction of all theexperimentally tested ligands varied between 23-60% depending on the ligand, temperatureand solvent ratio used in the reaction.