Search results for "cross-coupling"
showing 10 items of 56 documents
Iodocyclization of 2-Methylthiophenylacetylenes to 3-Iodobenzothiophenes and their coupling Reactions under More Sustainable Conditions
2022
We report the first example of iodocyclization of readily available 2-methylthiophenylacetylenes in a deep eutectic solvent (ChCl/urea 1/2, mol/mol) as recyclable and more sustainable solvent with respect to the classical VOCs employed so far. The process successfully afforded a variety of 3-iodobenzothiophenes in good to high yields starting from differently substituted substrates, with the possibility to recycle the DES several times without appreciable lowering of the product yield. The 3-iodothiophenes thus synthesized are known to be important precursors of biologically active molecules and functionalized heterocycles, and were successfully employed for performing representative Sonoga…
Carbon–Phosphorus Coupling from C^N Cyclometalated Au III Complexes
2020
Abstract With the aim of exploiting new organometallic species for cross‐coupling reactions, we report here on the AuIII‐mediated Caryl−P bond formation occurring upon reaction of C^N cyclometalated AuIII complexes with phosphines. The [Au(C^N)Cl2] complex 1 featuring the bidentate 2‐benzoylpyridine (CCON) scaffold was found to react with PTA (1,3,5‐triaza‐7‐phosphaadamantane) under mild conditions, including in water, to afford the corresponding phosphonium 5 through C−P reductive elimination. A mechanism is proposed for the title reaction based on in situ 31P{1H} NMR and HR‐ESI‐MS analyses combined with DFT calculations. The C−P coupling has been generalized to other C^N cyclometalated Au…
Palladium nanoparticles immobilized on halloysite nanotubes covered by a multilayer network for catalytic applications
2018
The synthesis of pure fine chemicals for industrial purposes is one of the most attractive challenges of chemical research. The use of catalytic pathways mediated by palladium nanoparticles (PdNPs) for C-C bond formation is a useful way to obtain these kinds of compounds. To achieve this objective, the PdNPs can be efficiently loaded on a functionalized natural nanostructured support such as halloysite nanotubes (HNTs). Hybrid materials based on thiol functionalized halloysite nanotubes and highly cross-linked imidazolium salts were successfully developed and used for the stabilization of PdNPs. The HNT/Pd hybrids were thoroughly characterized from a physico-chemical point of view and teste…
Iron-Catalyzed Cross-Coupling Reactions of Alkyl Grignards with Aryl Chlorobenzenesulfonates
2021
Aryl sulfonate esters are versatile synthetic intermediates in organic chemistry as well as attractive architectures due to their bioactive properties. Herein, we report the synthesis of alkyl-substituted benzenesulfonate esters by iron-catalyzed C(sp2)–C(sp3) cross-coupling of Grignard reagents with aryl chlorides. The method operates using an environmentally benign and sustainable iron catalytic system, employing benign urea ligands. A broad range of chlorobenzenesulfonates as well as challenging alkyl organometallics containing β-hydrogens are compatible with these conditions, affording alkylated products in high to excellent yields. The study reveals that aryl sulfonate esters are the m…
Triazolopyridines 23.1 Synthesis of 5,5'-bi[1,2,3]triazolo[5,1-a]isoquinoline
2004
5,5'-Bi[1,2,3]triazolo[5,1-a]isoquinoline 6 has been synthesised from [1,2,3]triazolo[5,1-a] isoquinoline 5 by four procedures, dimerisation by LDA, Stille and Suzuki self-coupling reactions, and Suzuki cross-coupling reaction. The last is the best. Compound 6 gives 1,1'- bi(acetoxymethyl)-3,3'-biisoquinoline 10 by triazolo ring opening by acetic acid. Abarca Gonzalez, Belen, Belen.Abarca@uv.es ; Ballesteros Campos, Rafael, Rafael.Ballesteros@uv.es ; Gay Roig, Bernat, bergay@alumni.uv.es
tBuLi-Mediated One-Pot Direct Highly Selective Cross-Coupling of Two Distinct Aryl Bromides.
2015
A Pd-catalyzed direct cross-coupling of two distinct aryl bromides mediated by tBuLi is described. The use of [Pd-PEPPSI-IPr] or [Pd-PEPPSI-IPent] as catalyst allows for the efficient one-pot synthesis of unsymmetrical biaryls at room temperature. The key for this selective cross-coupling is the use of an ortho-substituted bromide that undergoes lithium-halogen exchange preferentially.
Synthesis and stereochemical properties of "extended" biphenols bridged by ortho-, meta-, and para-phenylene spacers
2009
A series of isomeric biphenols based on para- (1), meta- (2), and ortho- (3) terphenyl backbones was synthesized. Suzuki cross-coupling methodology was employed for the construction of the terphenyl backbone of their methyl-protected precursors (respectively 8, 13, and 16). Using K2CO3 as the base, the best reaction conditions involved DMF at 100 °C as solvent. Anhydrous conditions greatly improved the yields of the sterically crowded systems (particularly 16). ortho-Terphenyls 3 and 16 exist as mixtures of syn/anti atropisomers in solution. Compound 16 crystallizes in the anti-in form. DFT calculations at the B3LYP/6-311+G(d,p) level indicate that for both compounds the anti-in form is mor…
Performances of symmetrical achiral ferrocenylphosphine ligands in palladium-catalyzed cross-coupling reactions: A review of syntheses, catalytic app…
2007
Abstract Ferrocene derivatives bearing donor atoms led to the generation of several classes of metallo-ligands, which collectively show an impressive diversity of applications, especially in metal-catalyzed modern organic reactions. Based on the impetus provided by the use of the diphosphine 1,1′-bis(diphenylphosphino)ferrocene (dppf) the investigations directed towards the synthesis of new ferrocenylphosphines remain of fundamental and industrial interest. The present review aims to describe the performances in palladium-catalyzed cross-coupling reactions of symmetrical achiral ferrocenylphosphine ligands, mainly diphosphines. We specifically choose to restrict our review efforts to these …
Evidences of release and catch mechanism in the Heck reaction catalyzed by palladium immobilized on highly cross-linked-supported imidazolium salts
2014
Abstract Palladium (10 wt%) on a highly cross-linked imidazolium-based material was used as catalyst in 0.1 mol% in the Heck reaction between several alkenes and aryl iodides. Products were obtained from good to high yields. Deeper investigations showed a release of Pd species in solution and their capture by the imidazolium-based support. When a sixfold amount of support was employed the re-captured Pd species (0.5–0.6 wt%) were not anymore catalytically active. This result represents a new interesting aspect of this work since the highly cross-linked imidazolium-based material can act also as Pd scavenger avoiding the release of the metal in solution. Important differences between Heck an…
Iron‐Catalyzed C(sp2)−C(sp3) Cross‐Coupling of Chlorobenzamides with Alkyl Grignard Reagents: Development of Catalyst System, Synthetic Scope, and Ap…
2019
Direct preparation of alkylated amide‐derivatives by cross‐coupling chemistry using sustainable protocols is challenging due to sensitivity of the amide functional group to reaction conditions. Herein, we report the synthesis of alkyl‐substituted amides by iron‐catalyzed C(sp2)−C(sp3) cross‐coupling of Grignard reagents with aryl chlorides. The products of these reactions are broadly used in the synthesis of pharmaceuticals, agrochemicals and other biologically‐active molecules. Furthermore, amides are used as versatile intermediates that can participate in the synthesis of valuable ketones and amines, providing access to motifs of broad synthetic interest. The reaction is characterized by …