854045-93-5Relevant academic research and scientific papers
Expanding Ligand Space: Preparation, Characterization, and Synthetic Applications of Air-Stable, Odorless Di- tert-alkylphosphine Surrogates
Barber, Thomas,Argent, Stephen P.,Ball, Liam T.
, p. 5454 - 5461 (2020)
The di-tert-alkylphosphino motif is common to many best-in-class ligands for late-transition-metal catalysis. However, the structural diversity of these privileged substructures is currently limited by the need to manipulate highly toxic, highly reactive reagents and intermediates in their synthesis. In response to this longstanding challenge, we report an umpolung strategy for the synthesis of structurally diverse di-tert-alkylphosphine building blocks via SN1 alkylation of in situ generated PH3 gas. We show that the products - which are isolated as air-stable, odorless phosphonium salts - can be used directly in the preparation of key synthetic intermediates and ligand classes. The di-tert-alkylphosphino building blocks that are accessible using our methodology therefore enable facile expansion of extant ligand classes by modification of a previously invariant vector; we demonstrate that these modifications affect the steric and electronic properties of the ligands and can be used to tune their performance in catalysis.
Synthesis of L-Au(I)-CF2H Complexes and Their Application as Transmetalation Shuttles to the Difluoromethylation of Aryl Iodides
García-Domínguez, Patricia
, p. 2923 - 2928 (2021/09/07)
We describe herein two alternative protocols to efficiently prepare difluoromethylgold(I) complexes bearing ancillary ligands with different electronic and steric properties. LAu-OX (X = H andt-Bu) species, formed in the presence of base, have been identified as intermediate complexes involved in these transformations. The application of these compounds as “CF2H transmetalation shuttles” from gold to palladium has been demonstrated in a Pd-catalyzed difluoromethylation reaction of aryl iodides, in which the Au-to-Pd transfer of “CF2H” is feasible under stoichiometric conditions. These findings will pave the way for catalytic manifolds in gold chemistry.
Synthesis, reactivity and catalytic activity of Au-PAd3complexes
Voloshkin, Vladislav A.,Saab, Marina,Van Hecke, Kristof,Lau, Sii Hong,Carrow, Bradley P.,Nolan, Steven P.
, p. 13872 - 13879 (2020/10/27)
Tri(1-adamantyl)phosphine (PAd3) possesses unique steric and electronic properties positioning it at the border between tertiary phosphines and N-heterocyclic carbenes (NHC). Novel Au-PAd3complexes were synthesized from the known [Au(PAd3)Cl]. We have optimised reaction conditions for the synthesis of this useful synthon in order to circumvent the formation of the [Au(PAd3)2]Cl. [Au(PAd3)Cl] was used to access a number of derivatives and some were deployed as catalysts. The hydration of alkynes was targeted to gauge the reactivity of Au-PAd3complexes and permit comparison with NHC and tertiary phosphine congeners.
Gold(I)-Catalyzed and Nucleophile-Guided Ligand-Directed Divergent Synthesis
Lee, Yen-Chun,Knauer, Lena,Louven, Kathrin,Golz, Christopher,Strohmann, Carsten,Waldmann, Herbert,Kumar, Kamal
supporting information, p. 5688 - 5699 (2018/10/31)
Transition metal catalysts can mediate a plethora of skeleton rearrangements of a range of substrates to construct complex small molecules. Yet, their potential to transform common substrates into distinct molecular scaffolds has not been fully explored to deliver biologically relevant small molecules. Gold(I)-catalyzed transformations of enynes are amongst the most intriguing rearrangements and provide opportunities to access a range of diverse scaffolds efficiently. In ligand-directed divergent synthesis (LDS), variation of ligands in metal complexes determines the fate of substrates during their transformation into distinct scaffolds. For instance, variation of ligands for the gold(I) catalysts helps to transform oxindole derived 1,6-enynes into several distinct molecular frameworks. In this report, we present how ligand variation in gold(I) catalysts, nucleophile-additives and alkyl and alkynyl substitutions on the 1,6-enynes as well as replacement of the oxindole ring with a different privileged ring-system (PRS) influence the LDS approach to access a wider chemical space. Based on the experimental results, we propose several mechanistic pathways in gold(I)-catalyzed cycloisomerizations and cascade reactions of 1,6-enyne substrates leading to structurally distinct chemotypes.
Predicting Counterion Effects Using a Gold Affinity Index and a Hydrogen Bonding Basicity Index
Lu, Zhichao,Han, Junbin,Okoromoba, Otome E.,Shimizu, Naoto,Amii, Hideki,Tormena, Cláudio F.,Hammond, Gerald B.,Xu, Bo
supporting information, p. 5848 - 5851 (2017/11/10)
We have developed a gold affinity index and hydrogen bonding basicity index for counterions and have used these indexes to forecast their reactivity in cationic gold catalysis.
Building polycyclic indole scaffolds via gold(I)-catalyzed intra- and inter-molecular cyclization reactions of 1,6-enynes
Pérez-Galán, Patricia,Waldmann, Herbert,Kumar, Kamal
supporting information, p. 3647 - 3652 (2016/06/06)
A gold(I) catalyzed cycloisomerization of indolyl-1,6-enynes via 5-exo-dig cyclization is reported. The reaction passes through an intermediate whose fate can be steered to yield different indole polycyclic scaffolds through various intra- and inter-molecular cyclization reactions. One of the key transformations of indolyl-1,6-enynes was a formal [2+2+2] cycloaddition reaction with various aldehydes to afford natural product-like tetracyclic indoles.
Synthesis of Substituted Quinolizidines via a Gold-Catalyzed Double Cyclization Cascade
Nonaka, Shiori,Sugimoto, Kenji,Ueda, Hirofumi,Tokuyama, Hidetoshi
supporting information, p. 380 - 385 (2016/02/12)
A novel synthesis of quinolizidines by a cationic gold-catalyzed double cyclization cascade has been developed. The reaction was initiated by the gold-catalyzed 6-exo-dig cyclization of ynamides, which was followed by a second cyclization of an enamide intermediate to provide the corresponding quinolizidine derivatives. The utility of this reaction was demonstrated by application to the synthesis of multi-substituted quinolizidines and by the total synthesis of a quinolizidine alkaloid, (±)-lupinine.
Autotandem catalysis: Synthesis of pyrroles by gold-catalyzed cascade reaction
Ueda, Hirofumi,Yamaguchi, Minami,Kameya, Hiroshi,Sugimoto, Kenji,Tokuyama, Hidetoshi
supporting information, p. 4948 - 4951 (2015/04/27)
A novel synthesis of substituted pyrroles by a gold(I)-catalyzed cascade reaction has been developed. The reaction proceeded with an autotandem catalysis consisting of an initial addition of gold-acetylide to an acetal moiety and was followed by gold-catalyzed 5-endo-dig cyclization and aromatization. Gold catalysts play a dual role in activating nucleophilicity or electrophilicity of terminal acetylenes by forming gold-acetylides or by π-coordination. The formal (3 + 2) annulation of two components provided a variety of substituted pyrroles in a modular fashion.
Mechanistic study of gold(I)-catalyzed hydroamination of alkynes: Outer or inner sphere mechanism?
Zhdanko, Alexander,Maier, Martin E.
, p. 7760 - 7764 (2014/08/05)
An experimental mechanistic study of the gold(I)-catalyzed hydroamination shows the formation of conformationally flexible auro-iminium salts Au-Im, which originate from the protonation of a vinyl gold species. Rotation around the C-CAu bond is the reason
Cationic gold catalyst poisoning and reactivation
Kumar, Manish,Hammond, Gerald B.,Xu, Bo
supporting information, p. 3452 - 3455 (2014/07/21)
High gold affinity impurities (halides, bases) in solvents, starting materials, filtration, or drying agents could affect the reactivity of gold catalyst adversely, which may significantly reduce the TON of cationic gold-catalyzed reactions. Use of a suit
