New mixed phosphonate esters by transesterification of pinacol phosphonates and their use in aldehyde and ketone coupling reactions with nonstabilized phosphonates

Alkylpinacol phosphonates were prepared by rhodium-catalyzed olefin hydrophosphorylation, and attempted alpha-deprotonation of the pinacol derived alkyl phosphonates resulted in ring cleavage. The propensity of the alkylpinacol phosphonates to undergo ring opening was exploited to prepare phosphonic acid monomethyl esters in high yield by transesterification in acidulated methanol. Esterification and alkylation with aldehydes or ketones gave beta-hydroxy mixed phosphonate esters. tert-Butyl and benzylic phosphonate ester protective groups were introduced to improve the efficiency and functional group compatibility of beta-hydroxy phosphonate saponification. The beta-hydroxy phosphonic acid monomethyl esters were dehydrated with diisopropylcarbodiimide, which gave oxaphosphetane intermediates that collapse to an olefin. The overall reaction sequence complements the arsenal of Horner-Wadsworth-Emmons-type coupling reactions.     

Über eine Reaktion von o-Hydroxybenzylalkoholen mit Estern von Säuren des Phosphors mit der Koordinationszahl 3

Abstract

o-Hydroxybenzyl alcohol reacts with trimethyl phosphite under smooth conditions to o-hydroxyphenylmethane phosphonic acid dimethyl ester. This unusual reaction is of widest applicability. Derivatives of o-hydroxybenzyl alcohol independent of type, number or position of substituents in the ring, react with alkyl esters of phosphorous, phosphonous or phosphinous acids in an analogous process, forming the corresponding o-hydroxyphenylmethane phosphonic or phosphinic esters or phosphine oxides.     

Synthesis and surface activity of mono- and diphosphate ester mixture with different alkyl chain length

A series of alkyl phosphate esters were synthesized and each of them was a mixture of monophosphate and diphosphate esters in a high or low mono/dimole ratio. The structure of hexadecyl phosphate ester with a low mono/dimole ratio was confirmed by FTIR, ¹H NMR, and³¹P NMR. The surface tensions of these alkyl phosphate esters were analyzed using a surface tensionmeter. The results showed that the critical micelle concentration (CMC) and critical surface tension (γ_CMC) of phosphate esters with a high mono/di ratio decreased with the increase of alkyl chain length. However, for the phosphate esters with a low mono/di ratio, the CMC, and γ_CMC decreased initially and increased afterwards with the increase of alkyl chain length. Meanwhile, the butanol and octanol phosphate esters with a high mono/di ratio had higher CMC and γ_CMC than their low mono/di ones, while the dodecyl and hexadecyl phosphate esters presented an opposite result. The results indicated that the mono- and diphosphate esters in the mixture may have a synergistic effect on the arrangement of molecules.     

PHOSPHORUS-CONTAINING AMINOCARBOXYLIC ACIDS. COMMUNICATION IV.1 A CONVENIENT METHOD OF PHOSPHONIC ACIDS SYNTHESIS

Abstract

The communication is concerned with the synthesis of phosphonic aminocarboxylic acids by phosphorylation of diethyl ω-halogen alkyl acetamidomalonates with tris(trimethylsilyl) phosphite, followed by alcoholysis and acid hydrolysis of the resulting intermediate esters.     

Structural determination of nerve agent markers using gas chromatography mass spectrometry after derivatization with 3‐pyridyldiazomethane

Nerve agents are a class of organophosphorous chemicals that are prohibited under the Chemical Weapons Convention. Their degradation products, phosphonic acids, are analyzed as markers of nerve agent contamination and use. Because the phosphonic acids are non‐volatile and very polar, their identification by GC‐MS requires a derivatization step prior to analysis. Standard derivatization methods for gas‐chromatography electron‐impact mass‐spectrometry analysis give very similar spectra for many alkyl phosphonic acid isomers, which complicates the identification process. We present a new reagent, 3‐pyridyldiazomethane, for preparing picolinyl ester derivatives of alkyl methylphosphonic acids facilitating the determination of their structure by enhancing predictable fragmentation of the O‐alkyl chain. This fragmentation is directed by the nitrogen nucleus of the pyridyl moiety that abstracts hydrogen from the O‐alkyl chain, inducing radical cleavage of the carbon–carbon bonds and thereby causing extensive fragmentation that can be used for detailed structure elucidation of the O‐alkyl moiety. The separability of related isomers was tested by comparing the spectra of the picolinyl esters formed from twelve hexyl methylphosphonic acid isomers. Spectral library matches and principal component analysis showed that the picolinyl esters were more effectively separated than the corresponding trimethylsilyl derivatives used in the standard operating procedures. The suggested method will improve the unambiguous structural determination process for phosphonic acids. Copyright © 2013 John Wiley & Sons, Ltd.     

5-Hydroxypentylammonium acetate as a reusable ionic liquid catalyzes tandem Knoevenagel-phospha-Michael reaction of aldehydes, malononitrile and phosphites

5-Hydroxypentylammonium acetate as a task-specific ionic liquid promotes efficient tandem Knoevenagel-phospha-Michael reaction of phosphite esters with aryl/heteroaryl/alkyl/salicylaldehydes and malonitrile/ethyl cyanoacetate at room temperature in short reaction times. This simple procedure allows a series of ??-phosphonomalonates and 4-substituted 2-amino-4H-chromenes with phosphonic acid dialkyl esters to be synthesized in good to high yields in the presence of an ionic liquid for the first time.     

Phosphorus Analogues of Homoproline

Abstract

Aminophosphonic and aminophosphinic acid analogs of most of the natural amino acids have been synthesized recently (1). We describe here the synthesis of phosphonic and phosphinic analogs of the natural iminocarboxylic acid homoproline. The compounds were obtained by the iminoalkylation of P(O)H-containing organophosphorus compounds with the trimer of tetrahydropyridine. This trimer adds three equivalents of dialkyl phosphite or monoalkyl alkyl(ary1) phosphonite to form the esters of piperidine-2-phosphonic or piperidine-2-alkyl (ary1)phosphinic acids. Hydrolysis of the esters in acidic medium leads to the phosphorus analogs of homoproline.     

SIMPLE AND IMPROVED PREPARATION OF α-OXOPHOSPHONATE MONOLITHIUM SALTS

Some α-OxoPhosphonate monolithium salts were synthesized by a facile one-step procedure. In this way, α-(2,4-dichlorophenoxyacetoxy)alkyl phosphonic acid dimethyl esters 5 can be transformed into the corresponding phosophonate monolithium salts 6 without influence on the carboxylic ester group under mild conditions.     

Acetylene Phosphonates as Dienophiles: A Route to Carbocyclic and Aromatic Phosphonates and Diphos-Phonates

Abstract

Systematic research of unsaturated phosphonates, started at the end of the sixties, gave rise to a variety of acetylene phosphonic derivatives. The authors worked out two significant routes to these compounds, (1) action of PCl₅ upon some alkynes followed by HCl elimination which gives alkyne dichlorophosphonates. and (2) Arbuzov reaction of P_III esters with halo- and dihaloalkynes which gives different phosphono- and diphosphonoacetylenes. The phosphonic groups are electron-withdrawing, and acetylenephosphon-ates are typical dienophiles in Diels-Alder cycloaddition of diene-donor/dienophile-acceptor type. Phosphonic esters are less active than corresponding dichlorophosphonates, but diphosphonic esters expose high reactivity. Haloethyne- and dialkylaminoethynephosphonates are sufficiently active in the reaction with simple dienes (butadiene, iso-prene, 2,3-dimethylbutadiene and piperylene), but we were not able to introduce alkyl- or arylacetylene phosphonic esters in the cycloaddition.     

Comparative study of self‐assembly of a range of monofunctional aliphatic molecules on magnetron‐sputtered aluminium

The adsorption of a range of organic molecules from toluene onto the oxidized surface of magnetron‐sputtered aluminium metal is studied using sessile drop water contact angle measurements. Molecules with different head group functionalities and various chain lengths are considered, including alkyl carboxylic acids, alkyl phosphonic acids, alkyl amines, alkyl trimethoxysilanes, alkyl trichlorosilanes and epoxy alkanes. Alkyl phosphonic and carboxylic acids are identified as readily forming the most well‐packed monolayers on the aluminium surface, whereas the others adsorb less well and the chlorosilanes polymerize as a result of combination with moisture to form a thick deposit. The high‐adsorption‐density monolayers of alkyl phosphonic and carboxylic acids were studied using polarization modulation infrared reflection–absorption spectroscopy (PM‐IRRAS) and x‐ray photoelectron spectroscopy (XPS): PM‐IRRAS reveals relatively poorer ordering of the C₁₀ alkyl carboxylic acid monolayer compared with that formed from the phosphonic acid, and XPS data suggest that this is likely to relate to a lower ability to displace preadsorbed volatile organic compounds. Copyright © 2004 John Wiley & Sons, Ltd.     

Fragmentation‐Related Phosphonylation of Nucleophiles Utilizing P‐Alkyl 2,3‐oxaphosphabicyclo[2.2.2]octene 3‐oxide Precursors

New P‐alkyl 2,3‐oxaphosphabicyclo‐[2.2.2]octene 3‐oxides were synthesized by the Bayer–Villiger oxidation of the corresponding 7‐phosphanorbornene 7‐oxides and were used as precursors for reactive alkylmetaphosphonates useful in the phosphonylation of alcohols. This is the first case that the reactivity of the two regioisomers formed by O‐insertion was differentiated and that the fragmentation‐related phosphonylation leading to phosphonic acid‐esters was achieved under microwave‐assisted conditions.     

Organogels with Fe(III) complexes of phosphorus-containing amphiphiles as two-component isothermal gelators

The properties of thermally reversible organogels in which the gelators consist of a phosphonic acid monoester, phosphonic acid, or phosphoric acid monoester and a ferric salt are probed by IR and NMR spectroscopies, optical microscopy, X-ray diffraction, rheology, and light and small-angle neutron scattering (SANS) techniques. This is one of a small number of two-component molecular gelator systems in which gelation can be induced isothermally. The data indicate that complexation between the phosphonate moieties and Fe(III) is accompanied by their in situ polymerization to form self-assembled fibrillar networks that encapsulate and immobilize macroscopically the organic liquid component. From SANS measurements, the cross-sectional radii of the cyclindrical fibers are ca. 15 A. The efficiencies of the gelators (based on the diversity of the liquids gelated, the minimum concentration of gelator required to make a gel at room temperature, and the temporal and thermal stabilities of the gels) have been determined. With a common ferric salt and liquid component, phosphonic acid monoesters are generally more efficient than phosphinic acids or phosphoric acid esters. Of the phosphonic acid monoesters, monophosphonates are better gelator components than bisphosphonates, and introduction of an omega-hydroxy group on the alkyl chain directly attached to phosphorus reduces significantly gelation ability. Several of the gels are stable for very long periods at room temperature. When heated, they revert to sols over wide temperature ranges. The structures of the gelator complexes and the mechanism of their formation and transformation to gels in selected liquids are examined as well.     

Studies on reactions of the N-phosphonium salts of pyridines—XV : Direct carbonylation of amines with carbon dioxide by a hydrolysis-dehydration reaction with phosphorus compounds

Carbon dioxide reacts with amines in the presence of phosphorus compounds and tertiary amines to give the corresponding ureas in high yield, and carbon disulfide gave thioureas. The presence of tertiary amines such as pyridine or imidazole facilitated the reactions. Aryl esters of phosphorous, phosphonous, phosphinous and phosphonic acids were effective, whereas their corresponding alkyl esters were ineffective. Various molar ratios of phosphite:tartiary amine:amine (aniline), produced variations in yield showing that the reaction proceeds via a carbamoyloxy and a thiocarbamoylthioxy N-phosphonium salt of the tertiary amine.     

Zum Reaktionsverhalten chlorsubstituierter Methanphosphonsäuredialkylester gegenüber Trialkylphosphiten,Dialkylphosphiten und Alkohol/Natriumalkoholat

On the Reaction of Chloro-substituted Methane Phosphonic Acid Dialkylester with Dialkylphosphites, Trialkylphosphites, or Alcohol/Sodium Alcoholate Dialkylesters of trichloromethane phosphonic acid react analogous to carbon tetrachloride with dialkylphosphites and alcohol in the presence of tertiary amines or with trialkylphosphites and alcohol yielding diesters of dichlormethane phosphonic acids and triesters of phosphoric acid. When esters of trichlormethane or dichloromethane phosphonic acid react with alcohols in the presence of sodium alcoholates a quantitative cleavage of P? C bond occurs and triesters of phosphoric acid and CHCl₃ or CH₂Cl₂ are formed.     

Studies on aryl H-phosphonates. 3. Mechanistic investigations related to the disproportionation of diphenyl H-phosphonate under anhydrous basic conditions

Diphenyl H-phosphonate undergoes under anhydrous reaction conditions a base-promoted disproportionation to triphenyl phosphite and phenyl H-phosphonate. On the basis of ³¹P NMR data the most likely mechanism for this transformation was proposed. In order to substantiate these findings and to get a deeper insight into the chemistry of aryl H-phosphonate esters, we carried out also some studies on activation of phenyl and diphenyl H-phosphonates with various condensing agents. We found that aryl vs alkyl esters of phosphonic acid often follow different reaction pathways during the activation, and this can most likely be traced back to higher electrophilicity of the phosphorus centre and to higher reactivity of the P-H bonds in aryl H-phosphonate derivatives.     

Novel and Convenient Approach to Synthesis of AZT／d4T H-phosphonates

A convenient, efficient and general method has been developed for synthesis of H-phosphonate mono and diesters of AZT and d4T through one-pot reaction of phosphonic acid with AZT or d4T and different alcohols using pivaloyl chloride as condensing agent under mild conditions.     

Stability of self-assembled monolayers on titanium and gold

Methyl- and hydroxyl-terminated phosphonic acid self-assembled monolayers (SAMs) were coated on Ti from aqueous solution. Dodecyl phosphate and dodecyltrichlorosilane SAMs were also coated on Ti using solution-phase deposition. The stability of SAMs on Ti was investigated in Tris-buffered saline (TBS) at 37 degrees C using X-ray photoelectron spectroscopy, contact angle goniometry, and atomic force microscopy. For comparison purposes, a hydroxyl-terminated thiol SAM was coated on Au, and its stability was also investigated under similar conditions. In TBS, a significant proportion of phosphonic acid or phosphate molecules were desorbed from the Ti surface within 1 day, while the trichlorosilane SAM on Ti or thiol SAM on Au was stable for up to 7 days under similar conditions. The stability of hydroxyl-terminated phosphonic acid SAM coated Ti and thiol SAM coated Au was investigated in ambient air and ultraviolet (UV) light. In ambient air, the phosphonic acid SAM on Ti was stable for up to 14 days, while the thiol SAM on Au was not stable for 1 day. Under UV-radiation exposure, the alkyl chains of the phosphonic acid SAM were decomposed, leaving only the phosphonate groups on the Ti surface after 12 h. Under similar conditions, decomposition of alkyl chains of the thiol SAM was observed on the Au surface accompanied by oxidation of thiolates.     

An approach to differentiating between multi‐ and monolayers using MALDI‐TOF MS

Analysis and confirmation of monolayer film thickness on metal oxide surfaces has proven to be challenging. XPS and AFM have been used to investigate the monolayer formation. However, these techniques are difficult to access and/or determine the composition of the organic molecules on the surfaces. Here we demonstrate the ability of MALDI‐TOF to characterize long alkyl chain phosphonic acid molecules in thin films on titanium, iron and stainless steel. These systems are known to be stable, strongly adhered films. The thin films were characterized by IR, AFM, contact angle measurements and the results were confirmed by MALDI‐TOF. Moreover, the MALDI‐TOF was used to differentiate between mono‐ and multilayers on planar surfaces. Copyright © 2007 John Wiley & Sons, Ltd.     

Kinetics and mechanism of the hydrolysis of esters of hydroxymethylphosphonic and hydroxymethylethylphosphinic acids

Conclusions The reactivity of ethyl esters of phosphonic and phosphinic acids containing a hydroxymethyl group at the phosphorus atom in their reaction with hydroxide anion is usually high as a consequence of intramolecular catalysis of the cleavage of the ester bond involving the ionized OH group. The spontaneous hydrolysis of these esters proceeds according to a mechanism analogous to that for other alkyl esters of tetracoordinated phosphorus acids.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2139–2140, September, 1985.     

Solid-state NMR spectroscopic study of the structure of grafted layers of phosphonic acid ester-modified hydroxyapatite

Interaction of hydroxyapatite (HAP) surface with phosphonic acid esters is studied under different conditions. The urgency of the study is due to the fact that HAP is one of the main components of bone tissue and is widely applied in the production of materials designed for filling bone defects. Modification of the surface properties of HAP may result in the development of materials with increased biocompatibility. It is revealed that, in the absence of solvents or in the medium of an aprotic solvent, phosphonic acid esters interact with HAP surface to yield pyrophosphate groups. The interaction with the surface does not take place in the presence of protic solvents.