Ethers phosphonic acid ester

A successful route to the dialkyl (l-raethyl-3-oxo-l-buCenyl)phosphonates (150) involves the conversion of compounds (148) via their enol silyl ethers into the phosphonic acid esters (149) which are then desilylaCed to give the desired esters (150) (Scheme 13). ... 

The rearrangement of (l,2-epoxyalkyl)phosphonic acid esters [626 R , R = H, Me or Ph, R R = (CH2)s] into esters of the (formylalkyl)phosphonic esters (627) is initiated thermally, but is also brought about very rapidly under the influence of BF3 etherate there was no evidence for the formation of the esters (R0)2P(0)C0CHR R through hydrogen migration. ... 

In the present paper, we examine the influence of structural variation within series of crown ether carboxylic acid and crown ether phosphonic acid monoalkyl ester carriers upon the selectivity and efficiency of alkali metal transport across three types of liquid organic membranes. Structural variations within the carriers include the polyether ring size, the lipophilic group attachment site and the basicity of ethereal oxygens. The three membrane types are bulk liquid membranes, liquid surfactant (emulsion) membranes and polymer-supported liquid membranes. 

The ionizable crown ethers which were utilized in the metal ion transport studies include a series of dibenzo crown ether carboxylic acids 1-6 and a series of crown ether phosphonic acid monoethyl esters"2, (Figure 2). Within the first series, the crown ether ring sizeTs systematically varied from 14-crown-4 to 16-crown-5 to 19-crown-6 in compounds 1, 2 and 2 respectively. For compounds 2, 4 and 5, the crown etfier ring size is held constant but tTie attachment site of the lipophilic alkyl group is altered. Finally, for compounds 2 and 6, the crown ether ring size and lipophilic... 

The structural variation of crown ether ring size charge was examined in more detail with the crown ether phosphonic acid monoethyl ester series 2-10 for which the crown ether ring size is systematically varied fi nTl5-crown-5 to 18-crown-6 to 21-crown-7 to 24-croM-8. As sljpwn in Figure 6, 2 exhibit transport... 

Figure 6. Competitive Transport of Alkali Metal Cations Across Bulk Chloroform Membranes by Crown Ether Phosphonic Acid Monoethyl Esters 7-10.

There have been further applications of MesSil and MesSiBr as dealkylating agents for ethers, esters, phosphonic acid esters, and alcohols, the last reaction using McsSil being a useful alkyl iodide synthesis. MesSil also converts acetals into ketones or sulphoxides into sulphides, whilst a mixture of PhSiMes and I2 is capable of dealkylating esters at ca. 110°C. ... 

Because of the possibility of racemization during the transesterification reaction (strong basic conditions) alternative methods are reported. These include transesterification in the presence of the KF/18-crown-6 ether 461 or the use of titanium tetraalkoxides. 471 The methods are efficient and represent a route to any required dialkyl ester using diphenyl esters as starting materials. Diphenyl groups can also be removed by hydrogenation in the presence of platinum dioxide (Adams catalyst) to provide the free phosphonic acid moiety directly)46 ... 

Of the methods of synthesis of cellulose esters, the one that has been most thoroughly studied is the reaction of trans-esterification, and this method is widely used for the synthesis of low-molecular-weight esters. The alcoholysis of a low-molecular-weight ester (methyl- and n -propyl-borate) with hydroxyl groups of cellulose was first used (37) for die preparation of cellulose borate. This was followed by the trans-esterification, with cellulose, of the esters of phosphorous acids (see above), i.e. mono-, di- and trimethylphosphites (71, 72, 75), esters of phosphonic acids (76), and also phenyl-/ -chloroethyl- and / -fluoroethylphosphites (77, 78). Of considerable interest is the reaction of alcoholysis, with cellulose, of the esters of aryl- and naphthalenesulphonic add, which results in the formation of cellulose ethers, rather than esters (79-81). 

General method for preparation of diphenyl esters of Gong-chain alkyl)phosphonic acids Equivalent amounts of the alcohol and triphenyl phosphite, together with 10 moles-% of sodium iodide, are placed in a flaskfitted with a thermometer, gas-inlet tube, stirrer, and distillation head water at about 50° is circulated through the attached condenser to prevent crystallization of the phenol. Nitrogen is led into the flask while the mixture is heated at the required temperature by a radiant heater until no more phenol distils (about 20 h). The remaining material is distilled at < 0.05 mm and the distillate is taken up in ether. The ethereal solution is washed with 2N-sodium hydroxide solution, dried and evaporated, and the residue is redistilled. 

Further esterification of monobenzyl benzylphosphonate may be carried through the Mitsunobu procedure, the best yields being achieved using the potassium salt of the substrate. Monoesters of iV-protected (1-aminoalkyl)phosphonic acids are further esterified by alcohols in the presence of BOP-type reagents [(l-aminoalkyl)alkylj- and [(l-aminoalkyl)aryl]-phosphinic acids, again as their potassium salts, have been converted into esters by reactive alkyl halides in the presence of 18-crown-6 ether (see also reference The... 

Alkyl ethers of dialkyl (hydroxymethyl)phosphonic acid have been obtained by a modified Arbuzov procedure in the presence of BF3 Et20, triethyl phosphite reacts with the formals ROCH20Ar according to Scheme 16 the reactions are best carried out in the presence of TiCl4 at -78 °C, but the Lewis acid catalyst and the experimental conditions have to be chosen carefully, otherwise mixed alkyl aryl esters are produced. Boron trifluoride etherate also catalyses the interaction of acetals of 4-substituted benzaldehydes with triethyl phosphite to give diethyl (a-alkoxybenzyl)phosphonates. Both aliphatic and aromatic aldehydes are reported to react with trialkyl phosphites at 100 °C to give the ethers 204 ... 

Deprotection procedures are readily available when, for example, in 283 and 285, R is benzyl, and removal relies on simple hydrogenolysis, and yields a dialkyl (2,3-dihydrox-ypropyl)phosphonate the product 288, from phenylglycidyl ether and a hydrogenphos-phonate ester, may likewise be deprotected in an appropriate manner to afford esters of the same phosphonic acid . 

Michaelis-Arbuzov reactions are not restricted to the use of the alkyl halide but may also be carried out with a corresponding ester or alcohol. On reaction with triethyl phosphite or a phosphorus(III) amide, the ester NCCH2CH2Z (Z = OAc) and ethers (with Z = OPh or OEt) afford the corresponding derivatives of (2-cyanoethyl)phosphonic acid [3-(dialkoxyphosphinyl)propanenitrile]. The same products are obtainable from 2-cyanoethanol. These reactions, and the conversion of406 into 408 and of407 into 409 , are reminiscent of those which take place between phosphorus(III) esters and 2-hydroxy-benzyl alcohols, and indeed they may be formulated in a similar manner (Chapter 2, Section II.A). Yet a further variation in reaction 22 is the involvement of substrates in... 

The 2-oxoazetidine-l-phosphonic acids (22) have been prepared by monodealkylation of the corresponding dialkyl esters with thiourea. The acid (22 R = R = H) was obtained, as its monoanilinium salt, by reaction of its bis-(trimethylsilyl) ester with aniline in ether. ... 

Phosphonic acid, butyl-, dibutyl ester. See Di butyl butyl phosphonate Phosphonic acid, (2-chloroethyl)-bis(2-chloroethyl) ether. See Bis (2-chloroethyl) 2-chloroethylphosphonate Phosphonic acid, dimethyl ester. See. Dimethyl hydrogen phosphite... 

Hydroxy-2,2,2-trichloroethylphosphonic acid dimethyl ester (2,2,2-Trichloro-1-hydroxyethyl) dimethylphosphonate 2,2,2-Trichloro-1-hydroxyethylphosphonate, dimethyl ester (2,2,2-Thchloro-l-hydroxyethyl) phosphonic acid dimethyl ester Trichlorophon Trichlorphene Trichlorphon Empirical C4H8CI3O4P Formula (CH30)2P(0)CH(OH)CCl3 Properties Wh. cryst. solid sol. in water, alcohols, ketones, benzene, chloroform, ether si. sol. in aromatic soivs., petrol, ether insol. in oils m.w. 257.45 dens. 1.73 (20/4 C) m.p. 83-84 C b.p. 

Methacrylamide monomers were also considered (Scheme 2.2). 2-Metha-crylamidoethylphosphonic acid was prepared from the expensive (2-ami-noethyl)phosphonic acid in one step. Other monomers (Scheme 2.2, monomers 1 and 2) were synthesized from bisphenol A diglycidyl ether. The ring-opening of epoxides was achieved with aqueous ammonia at high temperature and pressure and the subsequent reaction with diethyl (2-bromoethyl)phosphonate led either to mono- or disubstituted product. Targeted monomers were finally obtained after (i) reaction with methacryloyl chloride and (ii) hydrolysis of the phosphonated ester groups. 

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