Tetraorganylargentate(III) Complexes: Key Intermediates in Silver-Mediated Cross-Coupling Reactions

Abstract

The use of silver as a catalyst in cross-coupling reactions remains underdeveloped. We show by means of electrospray-ionization mass spectrometry that the diorganylargentates LiAgR′ 2 •Li(CN) (R′ = Me, Bu) formed in situ react with a wide scope of alkyl and aryl halides RX to afford the tetraorganylargentate(III) complexes R′ 3 AgR − . Upon fragmentation in the gas phase, these high-valent species readily undergo reductive elimination. The trimethylorganylargentates Me 3 AgR − furnish the synthetically desired crosscoupling products MeR with high selectivity, whereas the tributylorganylargentates Bu 3 AgR − yield more of the homocoupling product Bu 2 . Quantum chemical calculations reproduce the experimentally observed trends in reactivity and moreover provide insight into the structures and energetics of the species involved. Our findings indicate that the facile formation of tetraorganylargentate complexes and their high tendency toward reductive elimination can be exploited for the development of silver-mediated cross-coupling reactions as a viable alternative to established synthetic methods.

Unimolecular Reactivity of [Cu(R)(CF3)3]−Complexes (R=Organyl): Stepwise versus Concerted Mechanism in Copper‐Mediated Trifluoromethylation

“…A similar situation was found for the reductive elimination from high-valent organoargentates. [26] While the mechanistic insight obtained refers directly only to the probed gas-phase systems, the observed competition between concerted reductive elimination and stepwise radical losses presumably is also relevant for the reactivity of certain [Cu(R)(CF 3 ) 3 ] À ions in solution. For complexes bearing (secondary) alkyl groups R, cross-coupling reactions proceeding via a consecutive radical release and subsequent recombination should be taken into consideration.…”

Fully Automated Unconstrained Analysis of High-Resolution Mass Spectrometry Data with Machine Learning

“…Complex mixtures are important in many areas of life sciences and chemistry, from the analysis of natural products , and metabolomics , to the investigation of chemical reaction mechanisms. − Due to its superior resolution and sensitivity, high-resolution mass spectrometry (MS) with an electrospray ionization source is one of the most versatile analysis methods. ,, Modern instruments detect compounds with tiny concentrations down to trace signals and can perform structure elucidation via tandem mass spectrometry experiments. This opens new ways for an in-depth understanding of complex dynamic processes, for instance, in biology and medicine. , Unfortunately, the main strengths of the method (sensitivity and resolution) result in very complex spectra, drastically increasing the interpretation time and requiring high qualification for the scientist. , As an example, less than 20% of metabolites were identified in the untargeted analysis. , It is not uncommon when ∼80% of signals remain uninterpreted in the recorded mass spectrum of reaction mixtures, biomolecular systems, natural organic matter, and others.…”

Origin of the different reactivity of the high‐valent coinage‐metal complexes [RCuiiiMe3]− and [RAgiiiMe3]− (R=allyl)**

“…[1,2] In contrast, analogous silver-mediated transformations are by far not that well established, [3,4] but the potential of silver to mediate the formation of carbon-carbon bonds has become a greater focus of attention just recently. [5][6][7][8][9][10] While the usefulness of organo-LiAgMe 2 •LiI/RI reaction system (Figure 1). [7] In the reaction solution of the organocuprate, the analogous ate complex [RCuMe 3 ] À was detected as well, but the results of the RI-NMR spectroscopic experiments indicated that the latter reacted towards the neutral [RCuMe 2 ] species and did not undergo a CÀ C coupling reaction (Figure 1, top).…”

“…Copper‐mediated C−C coupling reactions play an outstanding role in the field of organic synthesis [1,2] . In contrast, analogous silver‐mediated transformations are by far not that well established, [3,4] but the potential of silver to mediate the formation of carbon‐carbon bonds has become a greater focus of attention just recently [5–10] . While the usefulness of organoargentates in stoichiometric alkylation reactions was questioned on the basis of theoretical calculations and gas‐phase experiments in the past, [11,12] a collaboration between a few of us and the Ogle group has recently shown that a LiAgMe 2 ⋅LiI reagent indeed undergoes a cross‐coupling reaction with allyl iodide in THF [7] .…”

“…[ 1 , 2 ] In contrast, analogous silver‐mediated transformations are by far not that well established,[ 3 , 4 ] but the potential of silver to mediate the formation of carbon‐carbon bonds has become a greater focus of attention just recently. [ 5 , 6 , 7 , 8 , 9 , 10 ] While the usefulness of organoargentates in stoichiometric alkylation reactions was questioned on the basis of theoretical calculations and gas‐phase experiments in the past,[ 11 , 12 ] a collaboration between a few of us and the Ogle group has recently shown that a LiAgMe 2 ⋅LiI reagent indeed undergoes a cross‐coupling reaction with allyl iodide in THF. [7] By means of rapid‐injection (RI) NMR spectroscopy, the argentate( iii ) complex [RAgMe 3 ] − (R=allyl) formed from [AgMe 2 ] − was identified as the key intermediate in this reaction.…”