NEW DIMETHYL(METHYLENEOXYARYL)-PHOSPHINE OXIDES

Abstract

From dimethyl-chloromethyl-phosphine oxides and sodium phenolates of the corresponding mono-, di-and triphenols are prepared by the Williamson reaction new dimethyl(methyleneoxyaryl)phosphine oxides containing one, two or three phosphoryl groups.     

Coulombic Basis for Relative Hydrogen-Bonding Basicities and Conformational Energies of Tertiary Amine Oxides and Phosphine Oxides

The structures, energies, and natural atomic charges of 2-dimethylaminophenol oxide, 2-Me₂N-(O)C₆H₄OH, and 2-dimethylphosphinylphenol, 2-Me₂P(O)C₆H₄OH, in three different conformations were computed at the ab initio MP2/6-31G* level. Computed natural charges indicate distributions of electron density in amine oxides and phosphine oxides that are quite different from what is normally assumed on the basis of the formal charges in the usual representations of these compounds. The charges on nitrogen and phosphorus in these compounds are typically computed to be approximately zero on nitrogen and +2 on phosphorus, and the oxygen is considerably more negative in the phosphine oxide than in the amino oxide. Electronegativity differences thus play a larger role and formal charges a smaller one in determining atomic charges in these compounds than is generally believed. Despite the more negative oxygen in phosphine oxides, amine oxides are computed to be considerably more basic when participating in hydrogen bonding. Calculations treating the computed natural charges on these six conformations as point charges for classical approximations of the coulombic energies support the idea that the quantum mechanically computed relative energies are largely determined by coulombic interactions.     

Synthesis of ferrocene-based phosphine ligands via Cu-catalyzed reductive coupling of ferrocenyl ketone-derived tosylhydrazones and H-phosphorus oxides

Ferrocene-based phosphine oxides with various substituents at phosphorous atoms were synthesized by Cu-catalyzed reductive coupling of ferrocenyl ketone-derived tosylhydrazones and H-phosphorus oxides. Followed by the reduction of ferrocene-based phosphine oxides, 1-substituted ferrocene-based phosphine ligand 7 and 1,1′-disubstituted ferrocene-based phosphine ligand 9 were obtained. Josiphos type ligand 8 were produced after ortho-lithiation of 7 and trapping with chlorodiphenyl phosphine or chlorodicyclohexylphosphine.     

Thermal rearrangement of bis(hydroxymethyl)phosphines as a way to P-chiral phosphine oxides

Bis(hydroxymethyl)(2-pyridyl)- and bis(hydroxymethyl)-[(2-pyridyl)ethyl]phosphines on heating to 180 °C undergorearrangement leading to racemic P-chiral tertiary P-methyl-P-(hydroxymethyl)-containing phosphine oxides. The spontaneous self-resolution of these enantiomer mixtures during the crystallization was demonstrated.     

Evaluation of bifunctional chiral phosphine oxide catalysts for the asymmetric hydrosilylation of ketimines

A series of bifunctional phosphine oxides have been prepared and evaluated as catalysts for the trichlorosilane mediated asymmetric hydrosilylation of ketimines. bis-Phosphine oxides, hydroxy-phosphine oxides, and biaryl phosphine oxides all demonstrated good catalytic activity, but poor to moderate enantioselectivity. A bis-P-chiral phosphine oxide displayed the highest enantioselectivity of 60%.     

Synthesis of polymers containing tertiary phosphine oxides using complex bases

Tertiary phosphine oxides have been prepared in excellent yield from primary alkyl halides or aromatic halides and activated sodium phosphinates obtained by reaction of dialkyl phosphine oxides with complex bases (NaNH₂/tBuONa). This reaction has been successfully applied to soluble and cross-linked bromopolystyrenes and to macroporous polystyrenes with bromooctyl substituents giving polymers which contain pendant phosphine oxide groups.     

Studies on highly regio- and stereoselective fluorohydroxylation reaction of 3-aryl-1,2-allenyl phosphine oxides with Selectfluor

The fluorohydroxylation of allenyl phosphine oxides with Selectfluor in commercial MeCN without prior treatment or a mixed solvent of anhydrous MeCN (refluxed over CaH₂ and distilled before use) and 7.0 equiv of H₂O or MeNO₂/H₂O=10/1 afforded 2-fluoro-3-hydroxy-1(E)-alkenyl diphenyl phosphine oxides in moderate yields with very high regio- and stereoselectivities. The E-stereoselectivity is believed to be controlled by the phosphine oxide functionality. In the reaction of 3-(4-methoxyphenyl)-1,2-propadienyl diphenyl phosphine oxide, further fluorination on the electron-rich phenyl ring was also observed.     

Synthesis of chelating tertiary phosphine oxides via palladium-catalysed C–P bond formation

Bis(diphenylphosphine oxides) and bis(tert-butyl(phenyl)phosphine oxides) of 1,10-phenanthroline, 2,2′-bipyridine and pyridine were synthesised in good yields via the Pd(OAc)₂/dppf mediated cross-coupling reactions between 6,6′-dichloro-2,2′-bipyridine, 2,9-dichloro-1,10-phenanthroline, or 2,6-dichloropyridine and the corresponding secondary phosphine oxides. These compounds represent potential tetradentate chelating ligands for ions of f-block elements.     

Addition of secondary phosphines to a vinyl ether of diacetone-d-glucose: a new approach to optically active phosphines and their derivatives

Secondary phosphines react readily with a vinyl ether of diacetone-d-glucose under radical initiation conditions to give, in high yield, anti-Markovnikov adducts, diorganyl{2-[3-O-(1,2:5,6-di-O-isopropylidene)-d-glucofuranosyloxy]ethyl}phosphines, which oxidize almost quantitatively upon reacting with air oxygen or elemental sulfur to form the corresponding optically active phosphine oxides or sulfides.     

Metal-free reduction of tertiary phosphine oxides with Hantzsch ester简

The （COCl）2/Hantzsch ester is found to be an effective system for the metal-free reduction of tertiary phosphine oxides. The reaction proceeds under mild conditions, and is applicable to triarylphosphine oxides and alkyldiarylphosphine oxides to produce the corresponding tertiary phosphines in good to excellent yields. This new finding provides a practical, convenient and metal-free method for the reduction of tertiary phosphine oxides to tertiary phosphines, and shows potential application in organic synthesis.     

Structures and Unexpected Dynamic Properties of Phosphine Oxides Adsorbed on Silica Surfaces

Solid‐state NMR spectroscopy of selected phosphine oxides adsorbed on silica surfaces establishes the surface mobilities, even of phosphine oxides with high melting points. Crystal structures of the adducts Ph₃PO ? HOSiPh₃ and Cy₃PO ? H₂O indicate that the interactions with silica involve hydrogen bonding of the P?O group to adsorbed water and surface silanol groups.     

Phosphorus-based allenes as scaffolds in cycloaddition and cyclization reactions

ABSTRACT

In this article, we describe some of our results on the reactions of allenylphosphonates/allenyl phosphine oxides and allenyl diazaphosphole oxides, primarily cycloaddition and cyclization reactions. Depending on the substituents, both the α,β and β,γ -cycloaddition products have been observed. A novel cyclization reaction of a functionalized allenylphosphine oxide with diethylamine leading to 3-diethylamino-4-diphenylphosphinoyl-1-naphthol is reported. Representative compounds have been characterized by X-ray crystallography.     

Synthesis of allyl phosphine oxides/boranes via Horner reaction of bis(diphenylphosphine)ethane monoxide reagent with an aldehyde

The Horner-Wittig addition-elimination reaction using bis(diphenylphosphine)ethane monoxide [DIPHOS(O)] with an aldehyde affords Z-allyl phosphine oxides/boranes. Alternatively, the stereoselective Lewis acid mediated intermolecular reduction of its γ-ketobisphosphoranes and stereoselective intramolecular reduction of γ-ketophosphine·borane derivatives followed by elimination of diphenylphosphinate affords E-allyl phosphine oxides/boranes with good to high selectivity. Allyl phosphine oxides are common intermediates in the synthesis of polyenes.     

Bifunctionalized allenes. Part XXI. Electrophilic cyclization and addition reactions of 3-(α- or β-hydroxyalkyl)-allenylphosphonates and allenyl phosphine oxides

Abstract

The present paper discusses the electrophilic cyclization and addition reactions of 3-(α- or β-hydroxyalkyl)-allenylphosphonates and phosphine oxides. Treatment of 3-(α- or β-hydroxy-alkyl)-allenylphosphonates with electrophiles takes place with 5-endo-trig cyclization and gives 2-methoxy-2,5-dihydro-1,2-oxaphosphole 2-oxides as a result of the neighboring phosphonate group participation in the electrophilic cyclization. On the other hand, 3-(α- or β-hydroxyalkyl)-alk-(1E)-en-1-yl phosphine oxides were prepared by chemo-, regio-, and stereoselective electrophilic addition to the C²-C³-double bond in the 3-(α- or β-hydroxyalkyl)-alka-1,2-dienyl phosphine oxides and subsequent attack of the external nucleophile (halide anion). The paper proposes a possible mechanism that involves electrophilic cyclization and addition reactions of the phosphorylated (α- or β-hydroxyalkyl)allenes.     

Lipase-mediated stereoselective transformations of chiral organophosphorus P-boranes revisited: revision of the absolute configuration of alkoxy(hydroxymethyl)phenylphosphine P-boranes

The lipase-promoted kinetic resolution of a series of alkoxy(hydroxymethyl)phenylphosphine P-boranes proceeded with moderate stereoselectivity to give both the unreacted substrates and their O-acetyl derivatives. The absolute configurations of the products, which were earlier ascribed on the basis of the stereoselective reduction of the corresponding phosphine oxides with borane and comparison with the literature data concerning bicyclic phosphine oxides, were disputed by theoretical calculation. Some additional studies were carried out, including theoretical calculations and more accurate chemical correlation, which proved that the borane reduction of acyclic phosphine oxides proceeded with inversion of configuration at the phosphorus center and, therefore, the former assignment of the absolute configurations was incorrect. On this basis, the stereochemistry of the enzymatic reaction was ultimately determined. A mechanism of the borane reduction of acyclic phosphine oxides explaining inversion of configuration at phosphorus is proposed.     

Catalytic oxidation of organic substrates with hydrogen peroxide in two-phase systems in the presence of peroxo-polyoxotungstates containing organic ligands

The prospects of using bifunctional homogeneous metal-complex catalysts based on peroxo-polyoxotungstates with organic ligands (tertiary phosphine oxides) were exemplified by oxidation of benzyl alcohol and cyclooctene with hydrogen peroxide in two-phase systems (organic phase — liquid phase).     

Studies on highly regio- and stereoselective selenohydroxylation reaction of 1,2-allenyl phosphine oxides with PhSeCl

The selenohydroxylation of readily available 1,2-allenyl phosphine oxides with PhSeCl in MeCN/H₂O afforded 3-hydroxy-2-phenylselanyl-1(E)-alkenyl diphenyl phosphine oxides in good yields with very high regio- and stereoselectivities including the high efficiency of the axial chirality transfer. The E-stereoselectivity is believed to be determined by the neighboring group participation effect of the diphenyl phosphine oxide functionality.     

Synthesis of organic phosphines and phosphine oxides from elemental phosphorus and phosphine in the presence of strong bases

Data on the reactions of elemental phosphorus and phosphine with electrophilic reagents are described systematically and analyzed. These reactions occur in the presence of strong bases and yield primary, secondary, and tertiary phosphines and phosphine oxides. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1695–1702, September, 1998.     

Efficient and green syntheses of novel γ-aminophosphonate and phosphine oxide derivatives

Two synthetic protocols leading to novel γ-aminophosphonate and phosphine oxide derivatives, by reductive amination of γ-phosphonylketones, are reported. The first method involved a two-step procedure. Imine intermediates were first isolated from the p-toluenesulfonic acid-catalyzed reaction of primary amines with γ-ketophosphonates and phosphine oxides, then reduced with NaBH₄ in refluxing ethanol. The second method consists of a one-pot procedure which includes the condensation of γ-ketophosphonates and phosphine oxides with primary amines, in the presence of molecular sieves, followed by reduction with NaBH₄. These methods offer significant advantages over prior reports, such as efficiency, generality, and good yields. Furthermore, they are green protocols avoiding hazardous hydrides and solvents.     

Facile synthesis of bisphosphine monoxides from Morita–Baylis–Hillman carbonates

A facile two-step synthesis of bisphosphine monoxides (BPMOs, with both the phosphine and phosphine oxide moieties within one molecule) from readily available Morita–Baylis–Hillman (MBH) carbonates was realized. Under the catalysis of DABCO, the MBH carbonates undergo allylic phosphorylation reaction with diphenylphosphine oxide or diethyl phosphonate to give monophosphine oxides bearing an activated alkene moiety; subsequent base-catalyzed hydrophosphination of the prepared monophosphine oxide with HPPh₂ readily affords the BPMOs.