Synthese von Derivaten des chiralen Ferrocenphosphan-Chelatliganden (BPPFA)

Sihler, R.; Werz, Udo; Brune, Hans Albert

doi:10.1016/0022-328x(89)85317-3

Cited by 15 publications

(8 citation statements)

References 5 publications

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“…Preparation of 2-[Di(2-trifluoromethylphenyl)phosphino]anisole ((2-BTF) 2 P( o -anis)). A solution of 0.667 g (1.67 mmol) of bis[2-(trifluoromethyl)phenyl]monochlorophosphine in dry THF was chilled to −78 °C under nitrogen in a 50-mL Schlenk flask. A Grignard solution prepared from 0.411 g (2.20 mmol) of 2-bromoanisole and 58.8 mg (2.40 mmol) of Mg was added dropwise via cannula.…”

Section: Methodsmentioning

confidence: 99%

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A Fluorescence-Based Assay for High-Throughput Screening of Coupling Reactions. Application to Heck Chemistry

1999

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A new fluorescence-based assay for high-throughput screening of reactions that couple two organic molecules is described. The assay involves reaction of one substrate containing a tethered fluorophore with a second molecule that is attached to a solid support. A successful coupling process is signaled by fluorescence of the solid support, which can be isolated by either simple centrifugation or filtration. To evaluate this assay in the context of a catalytic process under intense current study, we searched for improved, readily available phosphines for Heck chemistry. An acrylate containing a tethered coumarin was reacted with an aryl halide supported on a cross-linked polystyrene resin. Comparison of the results from our fluorescence-based assay with results from serial GC analysis showed that the fluorescence-based assay accurately selected the most active ligands for the Heck coupling of aryl bromides and chlorides. Two ligands chosen by the assay, tri(tert-butyl)phosphine and di(tert-butylphosphino)ferrocene, were found to be the most active systems to date for the olefination of unactivated aryl bromides, and di(tert-butylphosphino)ferrocene is the most efficient ligand for olefination of unactivated aryl chlorides.

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Section: Methodsmentioning

confidence: 99%

“…The residue was recrystallized from ethanol to give white crystals (1.54 g, 18%), mp ) 139 °C. 74 in dry THF was chilled to -78 °C under nitrogen in a 50-mL Schlenk flask. A Grignard solution prepared from 0.411 g (2.20 mmol) of 2-bromoanisole and 58.8 mg (2.40 mmol) of Mg was added dropwise via cannula.…”

Section: Methodsmentioning

confidence: 99%

A Fluorescence-Based Assay for High-Throughput Screening of Coupling Reactions. Application to Heck Chemistry

1999

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“…Dichloromethane was distilled from calcium hydride prior to use. Bis[2-(trifluoromethyl)phenyl]monochlorophosphine, o -(diphenylphosphino)methoxymethylbenzene ( 5 ), 1-[2‘-(diphenylphosphino)phenyl]methoxyethane ( 6 ), and tris( o -methoxymethylphenyl)phosphine ( 7 ) 48 were prepared by literature procedures. 4,4‘-Dibromobenzophenone ( 10 ), 1,4-dibromobenzene ( 14 ), 4,4‘-dibrombiphenyl, diphenylamine, and ditolylamine were purchased from commercial suppliers and were sublimed under reduced pressure prior to use; 1,3-dibromobenzene ( 17 ) was similarly purchased and vacuum distilled from calcium hydride.…”

Section: Methodsmentioning

confidence: 99%

Palladium-Catalyzed Synthesis of Pure, Regiodefined Polymeric Triarylamines

1999

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Triarylamine polymers were prepared by palladium-catalyzed amination of aryl halides, and the electrochemical and magnetic properties of these materials were studied. Through a careful evaluation of the catalytic and polymer chemistry involved in this process, triarylamine polymers that are exclusively linear and free of phosphorus impurity in the polymer chain have been prepared. To suppress molecular weight-limiting side reactions from palladium-catalyzed poly(N-arylaniline) polymerizations, a number of phosphines were screened in reactions of small molecules to form triarylamines. Of these phosphines, tris(o-methoxymethylphenyl)phosphine (7) and tri(tert-butyl)phosphine (8) led to quantitative amination without ligand arylation, aryl bromide hydrodehalogenation, or exchange of phosphine aryl groups with the aryl bromide. When these phosphines were used in polymerizations, significant improvements in molecular weights were observed, but an additional molecular weight limiting side reaction, the formation of cyclic oligomers, was not affected. Strategies to minimize cyclizations that compete with chain growth were explored, including the use of oligomeric monomers that greatly reduced the formation of cyclic oligomers. A chromatographic method completely removed low molecular weight cyclic oligomers. A number of poly(N-arylaniline) derivatives with M w values as high as 105 g/mol were synthesized by using the optimized palladium-catalyzed method, and the electronic and magnetic properties of these materials were investigated by cyclic voltammetry, magnetic susceptibility, and EPR spectroscopy.

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“…A few 1,1′-substituted ferrocenyl compounds with two dimesitylphosphanyl groups have been previously synthesized by reacting modified dilithioferrocene with Mes 2 PCl as reagents (G, H and I, Scheme 2). 54,55 However, their properties as bidentate ligands in metal complexation and homogeneous catalysis have not been explored in detail, except for a few instances of silver-mediated nucleophilic fluorination. 55 The synthesis of our mesityl-substituted bisphosphano ligand 1 was carried out by two complementary pathways.…”

Section: Syntheses and Complexationmentioning

confidence: 99%