Synthesis of Fluorinated Building Blocks by Transition‐Metal‐Mediated Hydrodefluorination Reactions

Abstract

The activation and functionalization of carbon-fluorine bonds can be considered as a major challenge in organometallic chemistry. The growing demand for means to introduce fluorine into new materials or into biologically active molecules has inspired the development of diverse synthetic strategies. Hydrodefluorination is regarded as a promising approach to access partially fluorinated building blocks from readily available perfluorinated bulk chemicals. We provide an overview of transition-metal-based complexes and catalysts that were developed to mediate hydrodefluorination reactions. Special emphasis will be placed on discussing the underlying mechanistic patterns and their impact on scope and selectivity. In addition, future requirements for further developing this field will be highlighted.

Influence of the Diphosphine Coordinated to Molybdenum and Tungsten Triangular M3S4 Cluster Hydrides in the Catalytic Hydrodefluorination of Pentafluoropyridine

“…Selective removal of fluorine atoms provides high value building blocks for the preparation of organofluorine fine chemicals [4]. In this sense, the simplest and more promising transformation consists in the replacement of C-F bonds by C-H bonds, commonly known as hydrodefluorination (HDF), which has been extensively studied in presence of transition metal complexes and a hydrogen source [5]. One of the most common reaction types described for intermolecular HDF involves the hydrogen/fluorine exchange between a metal-hydrido complex and the fluorinated organic substrate, as represented in equation 1, to form the hydrogen substituted organic product and the metal-fluorine complex.…”

Palladium-Mediated Organofluorine Chemistry

“…This topic has been reviewed recently covering all metal-catalyzed processes, 254 but just palladium mediated reactions will be discussed here. The replacement of fluorine by hydrogen is a reaction that has been observed in the catalytic hydrogenation of allylic, vinylic, benzylic and aromatic fluorides using heterogeneous palladium catalysts such as Pd on carbon.…”

Palladium-Catalyzed Cross-Coupling Reactions of Perfluoro Organic Compounds

“…The ORTEP drawing of 3 definitely shows that the palladium in 3 adopted a square-planar coordination geometry and was coordinated with two PPh 3 ligands in a trans manner (Figure 1). Complex 3 is the first example of a mononuclear trifluorovinyl complex generated by the carbon-fluorine bond cleavage of 1 with a well-defined structure [53,66]. Complex 3 seemed to be a promising reaction intermediate for the preparation of various trifluorovinyl compounds via cross-coupling reactions of TFE with organometallic reagents.…”

“…Against such a background, we started developing a novel strategy for their preparation from 1, because 1 is an economical bulk organofluorine feedstock for the production of poly(tetrafluoroethylene) and co-polymers with other alkenes [38][39][40]. However, to the best of our knowledge, no catalytic reactions involving 1 had been reported until we reported the first catalytic transformation reaction [41], while homogeneous catalytic reactions involving C-F bond activation have received an increasing amount of attention [42][43][44][45][46][47][48][49][50][51][52][53]. The C-F bond activation reaction of 1 had been achieved only in a few stoichiometric reactions [54][55][56].…”