Features of the reaction of 4-bromobut-2-enylphosphonium salts with monosubstituted hydrazines

(4-Bromobut-2-en-1-yl)triphenylphosphonium bromide reacted with phenylhydrazine at 2°C in the presence of sodium carbonate to form triphenyl[4-(2-phenylhydrazinylidene)but-2-en-1-yl]phosphonium bromide in 62% yield. The obtained N-phenylhydrazine derivatives cyclized into the corresponding pyrazoline derivatives of phosphonium salts. Unlike phenylhydrazine, ethylhydrazine reacted with (4-bromobut-2-ene-1-yl)triphenylphosphonium bromide under the same conditions to afford triphenyl[(1-ethyl-4,5-dihydro-1Hpyrazol-3-yl)methyl]- and -[(1-ethyl-1H-pyrazol-3-yl)methyl]phosphonium bromides in yields of 60 and 40%.     

Intramolecular dehydrochlorination of [2-(N’,N’-dialkylhydrazino)ethyl]phosphonium salts. Chemoselective alkaline hydrolysis of triphenylphosphonioalkylhydrazinium salts

The reactions of N,N-dimethylhydrazine and N-aminopiperidine with potential triphenylvinyl-and-propenylphosphonium bromides were used to obtain adducts by the α,β-double bonds of the latter. The resulting [2-(N’,N’-dimethylhydrazino)ethyl]phosphonium salts just on moderate heating in alcohol undergo dehydration leading to the corresponding hydrazone or α,β-unsaturated hydrazine derivatives. Contrary to that, [2-(N’,N’dimethylhydrazino)-2-methylethyl]triphenylphosphonium bromide under the same conditions does not undergo dehydration. The reaction of (3-bromopropyl)-and (4-bromobutyl)triphenylphosphonium bromides with N,N-dimethylhydrazine gives phosphoniohydrazinium salts with a tri-or tetramethylene common radical. When treated with equimolar amount of ethanolic sodium ethylate, the latter products undergo alkaline reduction of one of the phenyl groups to give the corresponding diphenylphosphinoylalkylhydrazinium salts in high yields.     

Reactions of (E)-(3-Aryl-3-oxoprop-1-en-1-yl)triphenylphosphonium Bromides with Arylhydrazines

(E)-(3-Aryl-3-oxoprop-1en-1-yl)triphenylphosphonium bromides reacted with arylhydrazines in an acidic medium to form hydrazones, the intramolecular heterocyclization of which led to the formation of (2,5- diaryl-2,3-dihydro-1H-pyrazol-3-yl)triphenylphosphonium bromides. Under the action of hydrobromic acid, the resulting quaternary phosphonium salts produced saturated (3-aryl-3-oxopropyl)triphenylphosphonium salts.

     

New Synthetic Routes to β-Olefinic Triphenylphosphonium Salts via (Diolefin)tricarbonyliron Complexes

The regio- and stereospecific preparation of β-olefinic triphenylphosphonium salts, starting from (diolefin)tricarbonyliron compounds is described. The latter are converted by various routes into either [(allyl)Fe(CO)₄]⁺ - or [(dienyl)Fe(CO)₃]⁺ - derivatives. The allylic cations, when reacted with P (C₆H₅)₃, yield uncomplexed (2-en-l-yl)triphenylphosphonium salts in good yields, while treatment of the dienyl cations with P(C₆H₅)₃ leads to the quantitative formation of (2,4-diene-l-yl)triphenylphosphonium ions still coordinated to the Fe (CO)₃-moiety. A method of oxidative decomplexation is described, by which the free phosphonium salts can be obtained. All new compounds were characterized by ¹³C-NMR spectra and also, where necessary, by ¹H-NMR decoupling experiments to confirm the stereochemical assignments. Many of the new phosphonium salts, potentially useful as Wittig reagents for natural product syntheses, are difficult to obtain by conventional unequivocal routes.     

Reaction of triphenyl(phenylethynyl)phosphonium bromide with α-aminoethers,dipiperidinomethane, and secondary amines

The reactions of triphenyl(phenylethynyl)phosphonium bromide with α-aminoethers lead to formation of triphenyl(2-amino-2-phenylvinyl)phosphonium bromides. In the case of acyclic aminoethers, this reaction is accompanied by the formation of the corresponding amine hydrobromide and triphenylphosphine oxide by a scheme analogous to that of alkaline hydrolysis of phosphonium salts and involving attack of the amine on the phosphorus atom. The reaction of the same salt with diethyl-or dipropylamine affords hydrobromides of the latter, while with piperidine, together with salts, its adduct by the triple bond is formed. Piperidinomethane with the same salt forms triphenylphosphonium (2-phenyl-2-piperidinovinyl)phosphonium bromide. Original Russian Text G.B. Bagdasaryan, P.S. Pogosyan, G.A. Panosyan, M.G. Indzhikyan, 2007, published in Zhurnal Obshchei Khimii, 2007, Vol. 77, No. 5, pp. 769–773.     

Tautomerization of α,β-and β,γ-unsaturated phosphonium salts resulting from the reaction of triphenylphosphine with β-bromomethacrylic acid. Nucleophilic addition at the γ position of the allyl group in phosphonium salt

Temperature factor was found to be determining in the isomerization of 2-carboxyprop-1-en-1-yl-and 2-carboxyprop-2-en-1-yl(triphenyl)phosphonium bromides. Elevated temperature favors formation of isomer with the double bond in the β,γ position with respect to the phosphonium group. Alkaline hydrolysis at room temperature promotes the reverse isomerization. The isomerization of 2-carboxyprop-1-en-1-yl(triphenyl)phosphonium bromide is hampered by addition of hydrobromic acid, as well as by carrying out its synthesis in the presence of aqueous HBr. Alkaline hydrolysis of 2-carboxyprop-1-enyl(triphenyl)phosphonium bromide and (E)-(2-carboxyvinyl)triphenylphosphonium chloride is accompanied by phenyl group migration to the α-position with formation of 2-methyl-3-(diphenylphosphoryl)-3-phenylpropionic acid and 3-(diphenyl-phosphoryl)-3-phenylpropionic acid, respectively. The possibility for nucleophilic addition at the γ position of the allyl group in 2-carboxyprop-2-enyl(triphenyl)phosphonium bromide was demonstrated using the reaction with triphenylphosphine as an example.     

Preparation of New Wittig Reagents and Their Application to the Synthesis of alpha,beta-Unsaturated Phosphonates

The Wittig reagent [(diethoxyphosphinyl)methylidene]triphenylphosphorane (1b) has been successfully synthesized for the first time via its phosphonium triflate salt (4a), by treating (diethoxyphosphinyl)methyl triflate with triphenylphosphine. The procedure has been applied to the synthesis of other phosphoranes and phosphonium salts. The new Wittig reagents thus synthesized were treated with various aldehydes and an activated ketone, affording the corresponding alpha,beta-unsaturated phosphonates. Triphenylphosphorane 1b and triphenylphosphonium 4a led to both cis and trans isomers with the latter being predominant, while trans isomers were almost exclusively formed when tributyl reagents (1c and 4d) were used.     

Cyclocondensations of Amidophenacylation Products of Triphenylphosphoranylideneacetonitrile

When heated in polyphosphoric acid, the products of amidophenacylation of the available triphenylphosphoranylideneacetonitrile undergo the Robinson-Gabriel cyclization followed by other transformations. Treatment of the resulting mixture with sodium perchlorate gave quaternary phosphonium salts of two types, viz. (2, 5-diaryl-1, 3-oxazol-4-ylmethyl) triphenylphosphonium perchlorates and [2-aryl-5-hydroxynaphtho[2, 1-d][1,3]oxazol-4-yl]triphenylphosphonium perchlorates. The first of these products was identified by alkaline dephosphorylation, and the structure of one of the representatives of the second class of compounds was established by X-ray diffraction.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005, pp. 556–560.Original Russian Text Copyright © 2005 by Panchishin, Smolii, Chernega, Rusanov, Drach.     

Reactions of 4-halo-2-alken(arylen)ylphosphonium salts with binucleophiles

Phosphonium salts with a 4-bromo-3-chlorobut-2-enyl or a 3-chlorobuta-1,3-dienyl group react with phenylhydrazine to give phenylhydrazones of corresponding 4-phospohonio-substituted 2-chloro-2-butenals. Reactions of phosphonium salts containing a 4-bromo-3-chlorobut-2-enyl group with a series of binucleophiles were studied. Under the action of urea, 1,4-dehydrobromination takes place to form a salt with a conjugated diene group, which undergoes partial 3,4-3,4-cyclization under the reaction conditions. Nucleophilic substitution reactions of [o-(bromomethyl)benzyl]triphenylphosphonium bromide with binucleophiles were also carried out.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 12, 2004, pp. 1992–1997.Original Russian Text Copyright © 2004 by Ovakimyan, Barsegyan, Pogosyan, Kikoyan, Panosyan, Indzhikyan.This revised version was published online in April 2005 with a corrected cover date.     

Laser microprobe mass spectrometry of quaternary phosphonium salts: Direct versus matrix-assisted laser desorption

The use of laser microprobe mass spectrometry (LMMS) for the structural characterization of thermolabile quaternary phosphonium salts has been evaluated. A comparison has been made between LM mass spectra obtained by direct analysis of “neat” organic salts and the corresponding “matrix-assisted” LM mass spectra. Main limitations of LMMS for the direct analysis of neat organic salts (i.e., no matrix) result from (1) formation of artifact ions that originate from thermal degradation and surface recombination reactions and (2) poor shot-to-shot reproducibility of the spectra. Dilution of the organic salts in a suitable, UV-absorbing matrix (e.g., nicotinic acid) significantly enhances the quality of the LM mass spectra. Improvements are: (1) an increase of the ion yield of preformed cations, (2) reduction or elimination of thermal decomposition and other deleterious surface reactions, and (3) a much better shot-to-shot spectral reproducibility. An interesting analytical feature is that these LM mass spectra, which contain only a few matrix peaks, can be obtained for subnanogram amounts of sample. The results also show that triphenylphosphonium salts with polycyclic aromatic substituents can be used as “molecular thermometers” to probe both the temperatures experienced by the sample molecules during the laser-induced desorption ionization process and the internal energies of the desorbed ion species. In this way, quaternary phosphonium salts can be used for evaluating whether improvements have been achieved by applying different sample treatments. Comparison of four different matrices (i.e., nicotinic acid, ammonium chloride, glycerol, and 3-nitrobenzylalcohol) indicates that the effectiveness of a matrix to reduce thermal degradation and to decrease the internal energies of the ions depends on the UV-absorption characteristics and the volatilization/sublimation temperature of the matrix material.     

Reactions of trialkyl(aryl)phosphonium-substituted acetals with resorcinol and its derivatives

The reactions of 2-tributylphosphonioacetaldehyde acetal with resorcinol and 2-methylresorcinol in an acidic aqueous-ethanol medium afford calix[4]resorcinols containing four tributylphosphonium groups at the lower rim. The corresponding reactions of the triphenylphosphonium analog give phosphonium salts containing the 2,2-diarylethyl moiety.     

Phosphonioethylation of phenylhydrazine and hydroxylamine and selected properties of the resulting derivatives

The reactions of phenylhydrazine and hydroxylamine with (-X-ethyl)triphenylphosphonium salts (X = Ph, Ph₃P⁺Br^–) (1, 2) afforded the corresponding -N-ethyl-substituted triphenylphosphonium salts (3, 4). The reaction of triphenyl(2-phenylhydrazinoethyl)phosphonium bromide 3with an aqueous solution of NaOH in benzene afforded a statistical mixture of the nisand transisomers of 2-(diphenylphosphoryl)acetaldehyde phenylhydrazone. (2-Hydroxyaminoethyl)triphenylphosphonium bromide reacted with sodium methoxide to give O-phosphobetaine.     

Interaction of 1-acylamino-2,2-dichloroethenyl(triphenyl)phosphonium chlorides with alkanolamines

Abstract

It is shown that the interaction of 1-acylamino-2,2-dichloroethenyl(triphenyl)-phosphonium chlorides with alkanolamines having a primary amino group results in the formation of 4-oxazolylphosphonium salts containing hydroxyalkylamine substituents at position 5 of the oxazole cycle. Under similar conditions the reaction of N-substituted alkanolamines with 1-acylamino-2,2-dichloroethenyl-(triphenyl)phosphonium chlorides leads to the formation of 1,3-oxazolidin-2-ylidene derivatives, in which the triphenylphosphonium group is located in the side chain. The structure of the new synthesized compounds has been reliably proven by elemental analysis, IR, ¹Н, ¹³С, ³¹Р NMR spectroscopy, mass spectrometry and single crystal X-ray diffraction.     

ω-Thioacetylalkylphosphonium salts: Precursors for the preparation of phosphonium-functionalised gold nanoparticles

Two new ω-thioacetylalkylphosphonium salts that function as masked cationic alkanethiolate ligands for the stabilisation of gold nanoparticles have been prepared. Both (3-thioacetylpropyl)triphenylphosphonium bromide and (6-thioacetylhexyl)triphenylphosphonium bromide were shown to form water-soluble gold nanoparticles of ca. 5-10 nm in size that are stable for up to six months. The related (3-thioacetylpropyl)diphenylphosphine oxide was also prepared but did not act as a stabilising ligand in gold nanoparticle formation.     

Synthesis and biological activity of quaternary phosphonium salts based on 3-hydroxypyridine and 4-deoxypyridoxine

Methods for the synthesis of quaternary phosphonium salts based on 3-hydroxypyridine and 4-deoxypyridoxine were developed. Some of obtained compounds possess high antibacterial and antitumor activity in vitro.     

Reactions of Phosphonioalkyl Derivatives of Phenylhydrazine and Hydroxylamine

Triphenyl- and tributyl[2-(2-phenylhydrazino)ethyl]phosphonium salts undergo dehydrogenation on heating to form the corresponding phenylhydrazones in high yields. The phenylhydrazone formed from the triphenylphosphonium salt can also be prepared from triphenyl(1-alkoxy-2-bromoethyl)phosphonium bromides. The latter reaction is proposed to involve reduction of the COC group with phenylhydrazine. N,N-Diphosphonioethylation and N,N-diphosphoniopropylation of hydroxylamine are performed. Alkaline hydrolysis of the resulting diphosphonium salts gave N, N-bis[2-(diphenylphosphoryl)ethyl(propyl)]hydroxylamines in high yields.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 7, 2005, pp. 1132–1136.Original Russian Text Copyright © 2005 by Ovakimyan, Barsegyan, Kikoyan, Indzhikyan.     

3- Substituted 3- Azabicyclo[3.3.1]nonan- 9- ols and Their Transformations Involving the Hydroxy Group

The reduction of 3-benzyl- and 3-tert-butoxycarbonyl-3-azabicyclo[3.3.1]nonan-9-ones with sodium tetrahydridoborate gave the corresponding alcohols as mixtures of á- and ä-epimers at a ratio of 2: 3. The resulting alcohols reacted with acetyl chloride and methanesulfonyl chloride at the hydroxy group to form O-acetyl and O-methylsulfonyl derivatives. Reactions of the latter with potassium iodide and sodium azide afforded 3-substituted 9-iodo(azido)-3-azabicyclo[3.3.1]nonanes. 9-Iodo derivatives were treated with triphenylphosphine to obtain triphenylphosphonium salts which were converted into the corresponding phosphonium ylides by the action of sodium methoxide in methanol, and the ylides readily reacted with benzaldehyde according to Wittig.     

Synthesis of 2-(alkylsulfanyl)propyltriphenylphosphonium bromides and their alkaline hydrolysis with potassium tert-butoxide

A series of 2-(alkylsulfanyl)propyltriphenylphosphonium salts was obtained starting from allyltriphenylphosphonium bromide. Alkaline hydrolysis of the obtained sulfur-containing quaternary phosphonium salts by the action of potassium tert-butoxide afforded 2-(alkylsulfanyl)propyldiphenylphosphine oxides in high yields.     

Comparative Studies on the Amidoalkylating Properties of N-(1-Methoxyalkyl)Amides and 1-(N-Acylamino)Alkyltriphenylphosphonium Salts in the Michaelis–Arbuzov-Like Reaction: A New One-Pot Transformation of N-(1-Methoxyalkyl)Amides into Phosphonic or Phosphinic Analogs of N-Acyl-α-Amino Acids

Abstract

It was demonstrated that N-(1-methoxyalkyl)amides do not react with trimethyl phosphite under neutral or basic conditions. The treatment of N-(1-methoxyalkyl)amides with trialkyl phosphites or dialkyl phosphonites, triphenylphosphonium tetrafluoroborate, and Hünig's base caused immediate formation of the corresponding 1-(N-acylamino)-alkyltriphenylphosphonium tetrafluoroborates, followed by the slow Michaelis–Arbuzov-like reaction of phosphonium salt with phosphites or phosphonites to α-(N-acylamino)-alkanephosphonic or α-(N-acylamino)alkanephosphinic acid esters, respectively. A plausible mechanism of the considered transformations, assuming an equilibrium between N-(1-alkoxyalkyl)amide, triphenylphosphonium tetrafluoroborate, 1-(N-acylamino)alkyltriphenyl-phosphonium salt, N-acylimine, and N-acyliminium salts, is discussed.     

1-Aminoalkylphosphonium Derivatives: Smart Synthetic Equivalents of N-Acyliminium-Type Cations,and Maybe Something More: A Review

N-acyliminium-type cations are examples of highly reactive intermediates that are willingly used in organic synthesis in intra- or intermolecular α-amidoalkylation reactions. They are usually generated in situ from their corresponding precursors in the presence of acidic catalysts (Brønsted or Lewis acids). In this context, 1-aminoalkyltriarylphosphonium derivatives deserve particular attention. The positively charged phosphonium moiety located in the immediate vicinity of the N-acyl group significantly facilitates C_α-P⁺ bond breaking, even without the use of catalyst. Moreover, minor structural modifications of 1-aminoalkyltriarylphosphonium derivatives make it possible to modulate their reactivity in a simple way. Therefore, these types of compounds can be considered as smart synthetic equivalents of N-acyliminium-type cations. This review intends to familiarize a wide audience with the unique properties of 1-aminoalkyltriarylphosphonium derivatives and encourage their wider use in organic synthesis. Hence, the most important methods for the preparation of 1-aminoalkyltriarylphosphonium salts, as well as the area of their potential synthetic utilization, are demonstrated. In particular, the structure–reactivity correlations for the phosphonium salts are discussed. It was shown that 1-aminoalkyltriarylphosphonium salts are not only an interesting alternative to other α-amidoalkylating agents but also can be used in such important transformations as the Wittig reaction or heterocyclizations. Finally, the prospects and limitations of their further applications in synthesis and medicinal chemistry were considered.