{"title":"Elementary Steps of Silver- and Gold-Mediated Trifluoromethylation Reactions","authors":"Bastian Zimmer, Konrad Koszinowski","doi":"10.1021/acs.organomet.4c00051","DOIUrl":null,"url":null,"abstract":"Due to the importance of the trifluoromethyl group in medicinal chemistry, trifluoromethylation reactions are in high demand. Most of the reported trifluoromethylation protocols rely on copper complexes, whose mechanistic role in these transformations has been analyzed extensively. First evidence also points to the potential of silver and gold complexes for enabling trifluoromethylation reactions, but a more detailed mechanistic understanding of these processes is still lacking. Here, we use electrospray-ionization mass spectrometry to study the formation of [Ag(R)(CF<sub>3</sub>)<sub>3</sub>]<sup>−</sup> and [Au(R)(CF<sub>3</sub>)<sub>3</sub>]<sup>−</sup> (R = Me, Et, <sup><i>n</i></sup>Bu, <sup><i>s</i></sup>Bu, allyl, aryl) in solution and characterize their unimolecular reactivity by gas-phase fragmentation experiments and quantum chemical calculations. The argentate complexes undergo both concerted reductive eliminations of RCF<sub>3</sub> and 2-fold radical losses of R<sup>•</sup> and CF<sub>3</sub><sup>•</sup>. Like in the case of the analogous cuprate complexes, the branching ratio between the two competing fragmentation channels is controlled by the stability of the R<sup>•</sup> radicals. In contrast, the calculated barriers of the corresponding fragmentation reactions of the aurates are much higher, for which reason these complexes dissociate by alternative pathways and do not afford the RCF<sub>3</sub> products.","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.5000,"publicationDate":"2024-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Organometallics","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1021/acs.organomet.4c00051","RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, INORGANIC & NUCLEAR","Score":null,"Total":0}
引用次数: 0
Abstract
Due to the importance of the trifluoromethyl group in medicinal chemistry, trifluoromethylation reactions are in high demand. Most of the reported trifluoromethylation protocols rely on copper complexes, whose mechanistic role in these transformations has been analyzed extensively. First evidence also points to the potential of silver and gold complexes for enabling trifluoromethylation reactions, but a more detailed mechanistic understanding of these processes is still lacking. Here, we use electrospray-ionization mass spectrometry to study the formation of [Ag(R)(CF3)3]− and [Au(R)(CF3)3]− (R = Me, Et, nBu, sBu, allyl, aryl) in solution and characterize their unimolecular reactivity by gas-phase fragmentation experiments and quantum chemical calculations. The argentate complexes undergo both concerted reductive eliminations of RCF3 and 2-fold radical losses of R• and CF3•. Like in the case of the analogous cuprate complexes, the branching ratio between the two competing fragmentation channels is controlled by the stability of the R• radicals. In contrast, the calculated barriers of the corresponding fragmentation reactions of the aurates are much higher, for which reason these complexes dissociate by alternative pathways and do not afford the RCF3 products.
期刊介绍:
Organometallics is the flagship journal of organometallic chemistry and records progress in one of the most active fields of science, bridging organic and inorganic chemistry. The journal publishes Articles, Communications, Reviews, and Tutorials (instructional overviews) that depict research on the synthesis, structure, bonding, chemical reactivity, and reaction mechanisms for a variety of applications, including catalyst design and catalytic processes; main-group, transition-metal, and lanthanide and actinide metal chemistry; synthetic aspects of polymer science and materials science; and bioorganometallic chemistry.