LUMO LOWERING

Abstract

One of the applications of Transition Metals in organic chemistry is due to their capability to function as catalysts for many reactions. Metals with empty d orbitals can coordinate with organic compounds, leading to high levels of yields and control of the expected products. Several reactions related to different projects have been setted up. The principal projects involved the Phauson-Khand reaction as well as the Carboxylic Acid-Selective Aldol Reaction. In the Phauson-Khand reaction an alkyne coordinates with a transition metal forming an complex that will react with a reactive partner, finally leading to the production of five membered carbocycles. Five membered carbocycles are important building blocks for many biological active molecules. Moreover, some cyclopentenones (e.g. cyclopentenone prostaglandins) exhibit characteristic biological activity. Alkene compounds have been studied to be interesting reactive partners. Their reactivity is related to the back donation of electrons from the d orbitals of a transition metal atom to the p* orbitals of the alkene. In our study we tried to synthetize a proper boronic acid to function as a co-catalyst in the Phauson-Khand reaction, consistent with the LUMO lowering strategies for increase the scope of this reaction. A second series of reactions were related to the Carboxylic Acid-Selective Aldol Reaction. Different boronic acids have been used to catalyze a reaction between a specific aldehyde and phenilacetic acid using a set of different bases as well as solvents. The scope was to screen the best conditions for this reaction to give rise to the expected product in acceptable yields. Proton NMR, Thin Layer Chromatography, IR spectrometry and GC-MS have been useful tools to analyze the outcome of the different reactions setted up so far. Rotor Vaporation, Vacuum filtration and Column Chromatography have been used for each specific reaction to purify the samples before performing the analytical investigations