Diastereoselective Synthesis of Dialkylated Bis(phosphino)ferrocenes: Their Use in Promoting Silver-Mediated Nucleophilic Fluorination of Chloroquinolines
International audience; The diastereoselective synthesis of dialkylated ferrocenyl bis(phosphane)s bearing aryl, alkyl, and hetero- or polycyclic substituents on the phosphino groups is reported, together with their characterization in the solid state by X-ray structure analysis and in solution by multinuclear NMR spectroscopy. Introduction of various alkyl groups on the ferrocene backbone, namely, tert-butyl, isopropyl, and trimethylsilyl, has a significant influence on the stereoselectivity of the ensuing lithiation/phosphination reactions. Only the introduction of the tert-butyl groups ensures both a high yield and perfect diastereoselectivity, which leads to the exclusive formation of t…
Functionalized Tri‐ and Tetraphosphine Ligands as a General Approach for Controlled Implantation of Phosphorus Donors with a High Local Density in Immobilized Molecular Catalysts
Supported phosphine ligands are auxiliaries of topical academic and industrial interest in catalysis promoted by transition metals. However, both controlled implantation and controlled conformation of ligands should be achieved to produce immobilized catalysts that are able to structurally “copy” efficient homogeneous systems. We provide herein a general synthetic strategy for assembling a new class of branched tetra- and triphosphine ligands with a unique controlled rigid conformation, and thus providing a high local density of phosphorus atoms for extended coordination to the metal center. We prepared new functionalized cyclopentadienyl (Cp) salts to design polyphosphines that were “ready…
Hexaphosphine: A Multifaceted Ligand for Transition Metal Coordination
We report the synthesis and characterization of the first ferrocenyl polyphosphane incorporating six phosphorus donor atoms. In this unique ligand, the cyclopentadienyl rings of the ferrocenyl backbone adopt a staggered position, which leads to a piano-stool arrangement for each of the two sets of three P atoms facing the same direction. As a consequence of its remarkable flexibility, this hexaphosphane displays versatile coordination behaviour towards metals, leading to unexpected structures of palladium and platinum bimetallic complexes. Analogous molybdenum and rhodium complexes are more classical.
Conformational Control of Metallocene Backbone by Cyclopentadienyl Ring Substitution: a New Concept in Polyphosphane Ligands Evidenced by “Through-Space” Nuclear Spin-Spin Coupling. Application in heteroaromatics arylation by direct C–H activation
The present study deals with the conformational control of the metallocene backbone within ferrocenyl polyphosphane ligands and their performance in the highly topical palladium-catalyzed heteroaromatics arylation by direct C−H activation. New substituted cyclopentadienyl rings were synthesized, which allowed the assembling of original tri- and diphosphanes. The bulky cyclopentadienyl lithium salts diphenylphosphino-3-(triphenyl)methylcyclopentadienyllithium (4) and 1,2-bis(diphenylphosphino)-4-(triphenyl)methylcyclopentadienyllithium (5) were prepared in excellent yield. The assembling of these new hindered cyclopentadienyl salts (Cp) with other Cp fragments was performed in order to prepa…
Modular functionalized polyphosphines for supported materials: previously unobserved (31)P-NMR «through-space» ABCD spin systems and heterogeneous palladium-catalysed C-C and C-H arylation.
The modular design of polyphosphines, diversely functionalized for facile immobilization on virtually any kind of support, is reported. Previously unobserved ABCD (31)P NMR spin-spin systems evidence the control exercised on the polyphosphines conformation. We illustrate the catalytic performance at low Pd loading of the recyclable immobilized polyphosphines in C-C bond formation reactions.
New concepts in multidentate ligand chemistry: effects of multidentarity on catalytic and spectroscopic properties of ferrocenyl polyphosphines.
This tutorial review devoted to ligand chemistry deals with the design and properties of ferrocenyl polyphosphines, an original class of multidentate ligands. The development of a varied library of ferrocenyl tetra-, tri- and diphosphine ligands is reviewed. The multidentate nature of these species has led to unique spectroscopic and catalytic properties, in which the spatial proximity of phosphorus atoms is crucial. Regarding their catalytic applications, the key issues of catalyst longevity and ultralow catalyst loadings are discussed. Another part is concerned with fundamental advances gained in physical chemistry for structure elucidation by the study of the intriguing “through-space” N…
ChemInform Abstract: New Concepts in Multidentate Ligand Chemistry: Effects of Multidentarity on Catalytic and Spectroscopic Properties of Ferrocenyl Polyphosphines
This tutorial review devoted to ligand chemistry deals with the design and properties of ferrocenyl polyphosphines, an original class of multidentate ligands. The development of a varied library of ferrocenyl tetra-, tri- and diphosphine ligands is reviewed. The multidentate nature of these species has led to unique spectroscopic and catalytic properties, in which the spatial proximity of phosphorus atoms is crucial. Regarding their catalytic applications, the key issues of catalyst longevity and ultralow catalyst loadings are discussed. Another part is concerned with fundamental advances gained in physical chemistry for structure elucidation by the study of the intriguing “through-space” N…
Ferrocenyl (P,N)-diphosphines incorporating pyrrolyl, imidazolyl or benzazaphospholyl moieties: Synthesis, coordination to group 10 metals and performances in palladium-catalyzed arylation reactions
Abstract Three novel symmetrical ferrocenyl diphosphines with tertiary phosphorus atoms holding respectively nitrogen-containing heterocyclic derivatives of pyrrole, imidazole and benzazaphosphole were synthesized and characterized. Up to now, integration of heteroaromatic fragments, or more generally hetero-cycles, as substituents on the tertiary phosphines of symmetrical ferrocenyl diphosphines has been limited to the furyl motif. Their coordination to palladium and platinum group 10 transition metals was exemplified, and analyzed using single crystal X-ray diffraction. The performances obtained in palladium-catalyzed copper-free Sonogashira and Suzuki cross-coupling reactions using bromo…
CCDC 988195: Experimental Crystal Structure Determination
Related Article: Matthieu Beaupérin, Radomyr Smaliy, Hélène Cattey, Philippe Meunier, Jun Ou, Patrick H. Toy, Jean-Cyrille Hierso|2014|Chem.Commun.|50|9505|doi:10.1039/C4CC04307C
CCDC 988196: Experimental Crystal Structure Determination
Related Article: Matthieu Beaupérin, Radomyr Smaliy, Hélène Cattey, Philippe Meunier, Jun Ou, Patrick H. Toy, Jean-Cyrille Hierso|2014|Chem.Commun.|50|9505|doi:10.1039/C4CC04307C