Fluorine and Gold: A Fruitful Partnership

Abstract

Gold-catalyzed reactions have witnessed an exponential growth in the past decade. When the unique modes of activation exhibited by gold species meet species with either fluorinated building blocks or fluorinating reagents, new opportunities arise for the development of new methodologies in fluoroorganic chemistry. Indeed, gold and fluorine truly formed a very fruitful partnership, and different types of reactivity emerged from their combination. This review gives an overview of such endeavors. The special properties imparted by fluorine to organic molecules have been exploited in gold-catalyzed processes, allowing for the generation of unprecedented fluorinated chemical entities. Thus, the interaction of gold salts with fluorinated building blocks has been revised. In a second section, recent developments in gold-catalyzed nucleophilic fluorinations have been covered. The development of new gold catalysts that stabilize the Au-F bond as well as recent mechanistic studies in the field raised the interest of these types of methodologies for the generation of new C-F bonds. The use of electrophilic fluorine sources enabled new modes of gold catalysis. The incorporation of Selectfluor as an external oxidant constituted a new paradigm in gold chemistry, incorporating the elusive Au(I)/Au(III) redox couple in gold-catalyzed transformations. This strategy provided access to both new fluorinated chemical entities and nonfluorinated derivatives by means of coupling reactions. Those topics have been reviewed in the last two sections.

An Organogold(III) Difluoride with a trans Arrangement

“…[1] Thed ifferences rely on the distinct effects induced by the most electronegative of the elements, fluorine,and are particularly conspicuous in gold chemistry. Yett hey are frequently proposed as key reaction intermediates, [3] just af ew are sufficiently stable to enable isolation. Yett hey are frequently proposed as key reaction intermediates, [3] just af ew are sufficiently stable to enable isolation.…”

“…[4] Focusing on gold(III), there is as mall set of monofluoride derivatives currently known, [5] but the number of available compounds decreases dramatically with increasing fluoride content. [7,8] As far as we know,t he single example of organogold(III) difluoride with trans geometry is given by the anion [trans-(CF 3 ) 2 AuF 2 ] À ,w hich was detected in solution along with the trifluoride [CF 3 AuF 3 ] À and various other species,b ut could not be separated. [7,8] As far as we know,t he single example of organogold(III) difluoride with trans geometry is given by the anion [trans-(CF 3 ) 2 AuF 2 ] À ,w hich was detected in solution along with the trifluoride [CF 3 AuF 3 ] À and various other species,b ut could not be separated.…”

“…[7,8] As far as we know,t he single example of organogold(III) difluoride with trans geometry is given by the anion [trans-(CF 3 ) 2 AuF 2 ] À ,w hich was detected in solution along with the trifluoride [CF 3 AuF 3 ] À and various other species,b ut could not be separated. [12] Now we report on an efficient and stereoselective synthesis of the elusive species [trans-(CF 3 ( 1). [12] Now we report on an efficient and stereoselective synthesis of the elusive species [trans-(CF 3 ( 1).…”

“…[7] The[trans-(CF 3 ) 2 AuF 2 ] À anion shows interesting behavior in the gas phase,a se xamined by tandem mass spectrometry (MS 2 ). Thus,a pparent elimination of CF 4 gives rise to small amounts of the mixed organogold(I) species [CF 3 AuF] À (Scheme 2c). By far the most favored process involves CF 2 extrusion [14] and formation of the trifluoride complex [CF 3 AuF 3 ] À with no change in the metal oxidation state (Scheme 2a).…”

Nobler than the Noblest: Noncubic Gold Microcrystallites

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Conventional gold comprising the cubic lattice is universally knownf or its stability.H owever,w ell knownt o chemists and metallurgists,t his nobility is challenged by reagents such as aqua regia, which dissolve gold to form as alt solution. [2] Thes urface stability of Au has been the subject matter of numerous experimental and theoretical studies in the last few decades. Herein, we report ac ombined experimental and theoretical investigation of the stability of Au microcrystallites bearing unconventional crystal lattices that exhibit enhanced stability towards Hg and aqua regia and practically no interaction with Cu during electroless plating.

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