Synthesis and Reactivity of Palladium Trifluorides and Fluorides Towards Aryl C-CF3 and C-F Bond Formation.

Abstract

The installation of carbon–fluorine and carbon-trifluoromethyl bonds in organic compounds can have a significant effect on the chemical and biological of the molecules. However, synthetically the selective incorporation of C–F/C–CF3 bonds into important biological targets remains a significant challenge. Palladium catalysis has been extremely successful in the selective incorporation of C-X (X = Cl, Br, I, OAc, Ar, N) bonds into molecules. Thus, an attractive strategy would be to utilize palladium C–X coupling methodologies to promote C–F/C–CF3 bond formation. This dissertation will discuss structural and mechanistic studies of palladium intermediates modeling Pd(0)/Pd(II) and Pd(II)/Pd(IV) catalytic systems towards aryl fluorination and trifluoromethylation. Structural analysis of Pd(II)-fluoride complexes will be presented focusing on the affects of steric and electronics on the metal center and the implications towards Pd(0)/Pd(II) Aryl–F coupling. Additionally, the reactivity of aryl Pd(II)–F and Pd(II)–CF3 complexes with stoichiometric quantities of electrophilic fluorinating agents resulting in Aryl–F and Aryl-CF3 bond coupling will be discussed. These reactions proceed to generate both electron rich and electron poor aryl fluorides and trifluorides in good yield. Observation of C–F/C–CF3 bond coupling from isolated sigma-aryl PdIV–F and PdIV–CF3 complexes will emphasize the viability of C–F/C–CF3 bond formation in a Pd(II)/Pd(IV) catalytic system.