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Organic Letters Jul 2010Arylphosphines and dialkylbiarylphosphines react with singlet oxygen to form phosphine oxides and phosphinate esters. For mixed arylphosphines, the most electron-rich...
Arylphosphines and dialkylbiarylphosphines react with singlet oxygen to form phosphine oxides and phosphinate esters. For mixed arylphosphines, the most electron-rich aryl group migrates to form the phosphinate, while for dialkylbiarylphosphines migration of the alkyl group occurs. Dialkylbiarylphosphines also yield arene epoxides, especially in electron-rich systems. Phosphinate ester formation is increased at high temperature, while protic solvents increase the yield of epoxide. The product distribution provides evidence for Buchwald's recent conformational model for the aerobic oxidation of dialkylbiarylphosphines.
Topics: Esters; Molecular Structure; Oxidation-Reduction; Oxides; Oxygen; Phosphines; Photochemistry; Stereoisomerism
PubMed: 20527907
DOI: 10.1021/ol101122u -
Chemical Society Reviews Jun 2008Nucleophilic phosphine catalysis has proven to be a powerful tool in organic synthesis, which can provide easy access to cyclic, bicyclic or polycyclic carbocycles and... (Review)
Review
Nucleophilic phosphine catalysis has proven to be a powerful tool in organic synthesis, which can provide easy access to cyclic, bicyclic or polycyclic carbocycles and heterocycles. Owing to their comparatively strong and readily tunable nucleophilicity, phosphines can be easily tailored to efficient annulation reactions with good control over reaction selectivity. This has resulted in a tremendous increase in their scope and in a concomitant number of reports where phosphine-triggered annulation reactions occur. This tutorial review summarizes the recent achievements in this area.
Topics: Catalysis; Cyclization; Molecular Structure; Organic Chemicals; Phosphines
PubMed: 18497927
DOI: 10.1039/b717758e -
Angewandte Chemie (International Ed. in... Sep 2017We report a fast Staudinger reaction between perfluoroaryl azides (PFAAs) and aryl phosphines, which occurs readily under ambient conditions. A rate constant as high as...
We report a fast Staudinger reaction between perfluoroaryl azides (PFAAs) and aryl phosphines, which occurs readily under ambient conditions. A rate constant as high as 18 m s was obtained between methyl 4-azido-2,3,5,6-tetrafluorobenzoate and methyl 2-(diphenylphosphanyl)benzoate in CD CN/D O. Furthermore, the iminophosphorane product was stable toward hydrolysis and aza-phosphonium ylide reactions. This PFAA Staudinger reaction proved to be an excellent bioothorgonal reaction. PFAA-derivatized mannosamine and galactosamine were successfully transformed into cell-surface glycans and efficiently labeled with phosphine-derivatized fluorophore-conjugated bovine serum albumin.
Topics: Azides; Fluorescent Dyes; Fluorine Compounds; Hydrolysis; Kinetics; Microscopy, Fluorescence; Phosphines; Polysaccharides; Proton Magnetic Resonance Spectroscopy
PubMed: 28796447
DOI: 10.1002/anie.201705346 -
Nature Dec 2020Hydroamination of alkenes, the addition of the N-H bond of an amine across an alkene, is a fundamental, yet challenging, organic transformation that creates an...
Hydroamination of alkenes, the addition of the N-H bond of an amine across an alkene, is a fundamental, yet challenging, organic transformation that creates an alkylamine from two abundant chemical feedstocks, alkenes and amines, with full atom economy. The reaction is particularly important because amines, especially chiral amines, are prevalent substructures in a wide range of natural products and drugs. Although extensive efforts have been dedicated to developing catalysts for hydroamination, the vast majority of alkenes that undergo intermolecular hydroamination have been limited to conjugated, strained, or terminal alkenes; only a few examples occur by the direct addition of the N-H bond of amines across unactivated internal alkenes, including photocatalytic hydroamination, and no asymmetric intermolecular additions to such alkenes are known. In fact, current examples of direct, enantioselective intermolecular hydroamination of any type of unactivated alkene lacking a directing group occur with only moderate enantioselectivity. Here we report a cationic iridium system that catalyses intermolecular hydroamination of a range of unactivated, internal alkenes, including those in both acyclic and cyclic alkenes, to afford chiral amines with high enantioselectivity. The catalyst contains a phosphine ligand bearing trimethylsilyl-substituted aryl groups and a triflimide counteranion, and the reaction design includes 2-amino-6-methylpyridine as the amine to enhance the rates of multiple steps within the catalytic cycle while serving as an ammonia surrogate. These design principles point the way to the addition of N-H bonds of other reagents, as well as O-H and C-H bonds, across unactivated internal alkenes to streamline the synthesis of functional molecules from basic feedstocks.
Topics: Alkenes; Amination; Amines; Aminopyridines; Ammonia; Catalysis; Chemistry Techniques, Synthetic; Hydrogen; Indicators and Reagents; Iridium; Ligands; Nitrogen; Phosphines
PubMed: 33142305
DOI: 10.1038/s41586-020-2919-z -
ACS Combinatorial Science Feb 2018We demonstrate that the Knoevenagel condensation can be exploited in combinatorial synthesis on the solid phase. Condensation products from such reactions were...
We demonstrate that the Knoevenagel condensation can be exploited in combinatorial synthesis on the solid phase. Condensation products from such reactions were structurally characterized, and their Michael reactivity with thiol and phosphine nucleophiles is described. Cyanoacrylamides were previously reported to react reversibly with thiols, and notably, we show that dilution into low pH buffer can trap covalent adducts, which are isolable via chromatography. Finally, we synthesized both traditional and DNA-encoded one-bead, one-compound libraries containing cyanoacrylamides as a source of cysteine-reactive reversibly covalent protein ligands.
Topics: Acrylamides; Combinatorial Chemistry Techniques; Cysteine; DNA; Gene Library; Ligands; Molecular Structure; Nitriles; Phosphines; Proteins; Solid-Phase Synthesis Techniques; Sulfhydryl Compounds
PubMed: 29298042
DOI: 10.1021/acscombsci.7b00169 -
Nature Communications Jul 2022Although transition metal-catalyzed reactions have evolved with ligand development, ligand design for palladium-catalyzed photoreactions remains less explored. Here, we...
Although transition metal-catalyzed reactions have evolved with ligand development, ligand design for palladium-catalyzed photoreactions remains less explored. Here, we report a secondary phosphine oxide ligand bearing a visible-light sensitization moiety and apply it to Pd-catalyzed radical cross-coupling reactions. The tautomeric phosphinous acid coordinates to palladium in situ, allowing for pseudo-intramolecular single-electron transfer between the ligand and palladium. Molecular design of the metal complexes aided by time-dependent density functional theory calculations enables the involvement of allyl radicals from π-allyl palladium(II) complexes, and alkyl and aryl radicals from the corresponding halides and palladium(0) complex. This complex enables radical cross-couplings by ligand-to-Pd(II) and Pd(0)-to-ligand single-electron transfer under visible-light irradiation.
Topics: Catalysis; Ligands; Oxides; Palladium; Phosphines
PubMed: 35831306
DOI: 10.1038/s41467-022-31613-9 -
ChemistryOpen Jan 2023We describe the synthesis and characterization of two classes of hybrid phosphino ligands functionalized with amino ester or amino acid groups. These compounds are built...
We describe the synthesis and characterization of two classes of hybrid phosphino ligands functionalized with amino ester or amino acid groups. These compounds are built either on a rigid planar phenyl platform or on a functionalized - conformationally controlled - rotational ferrocene backbone. Modifications at the -PR phosphino groups (R=aryl and alkyl, with various steric bulk, Ph, Mes, i-Pr, Cy) and at the amino acid/amino ester functions are reported, showing a valuable high modularity. The coordination chemistry of these compounds regarding palladium and gold was investigated, in particular with respect to the coordination mode of the phosphino groups and the preferred interaction with metals for the amino ester and amino acid functions. For all the hybrid ligands, based either on ferrocenyl or phenyl platforms, the (P,N)-chelating effect dominates in solution for coordination to Pd(II), while linear P-Au(I) complexes without interaction with the amino groups are assumed. The investigation of the catalytic activity of these new ligands in the demanding palladium-catalyzed Suzuki-Miyaura coupling of o-dibromoarenes with fluorophenylboronic acid underlined the importance of the amino ester dicyclohexylphosphinoferrocene for avoiding the deleterious homocoupling and arene oligomerization side-reactions that were otherwise observed with the other phosphine ligands.
Topics: Palladium; Amino Acids; Phosphines
PubMed: 36635048
DOI: 10.1002/open.202200190 -
Chemical Society Reviews May 2014Nucleophilic phosphine catalysis of allenes with electrophiles is one of the most powerful and straightforward synthetic strategies for the generation of highly... (Review)
Review
Nucleophilic phosphine catalysis of allenes with electrophiles is one of the most powerful and straightforward synthetic strategies for the generation of highly functionalized carbocycle or heterocycle structural motifs, which are present in a wide range of bioactive natural products and medicinally important substances. The reaction topologies can be controlled through a judicious choice of the phosphine catalyst and the structural variations of starting materials. This Tutorial Review presents selected examples of nucleophilic phosphine catalysis using allenes and electrophiles.
Topics: Aldehydes; Alkadienes; Alkenes; Catalysis; Imines; Ketones; Phosphines
PubMed: 24663290
DOI: 10.1039/c4cs00054d -
Angewandte Chemie (International Ed. in... Dec 2020RNA-RNA interactions are essential for biology, but they can be difficult to study due to their transient nature. While crosslinking strategies can in principle be used...
RNA-RNA interactions are essential for biology, but they can be difficult to study due to their transient nature. While crosslinking strategies can in principle be used to trap such interactions, virtually all existing strategies for crosslinking are poorly reversible, chemically modifying the RNA and hindering molecular analysis. We describe a soluble crosslinker design (BINARI) that reacts with RNA through acylation. We show that it efficiently crosslinks noncovalent RNA complexes with mimimal sequence bias and establish that the crosslink can be reversed by phosphine reduction of azide trigger groups, thereby liberating the individual RNA components for further analysis. The utility of the new approach is demonstrated by reversible protection against nuclease degradation and trapping transient RNA complexes of E. coli DsrA-rpoS derived bulge-loop interactions, which underlines the potential of BINARI crosslinkers to probe RNA regulatory networks.
Topics: Acylation; Azides; Cross-Linking Reagents; Escherichia coli; Phosphines; RNA, Bacterial
PubMed: 32845055
DOI: 10.1002/anie.202010861 -
The Journal of Organic Chemistry Jul 2022The arylthiol 4-mercaptophenylacetic acid (MPAA) is a powerful catalyst of selenosulfide bond reduction by the triarylphosphine...
The arylthiol 4-mercaptophenylacetic acid (MPAA) is a powerful catalyst of selenosulfide bond reduction by the triarylphosphine 3,3',3″-phosphanetriyltris(benzenesulfonic acid) trisodium salt (TPPTS). Both reagents are water-soluble at neutral pH and are particularly adapted for working with unprotected peptidic substrates. Contrary to trialkylphosphines such as tris(2-carboxyethyl)phosphine hydrochloride (TCEP), TPPTS has the advantage of not inducing deselenization reactions. We believe that the work reported here will be of value for those manipulating selenosulfide bonds in peptidic or protein molecules.
Topics: Catalysis; Indicators and Reagents; Peptides; Phosphines; Proteins; Sulfhydryl Compounds
PubMed: 35763672
DOI: 10.1021/acs.joc.2c00934