Phosphonic acids dialkyl esters

Arend, G., Schaffner, H., and Schramm, J., Process For The Production of (Meth)allyl Phosphonic Acid Dialkyl Esters, U.S. Patent 4,017,564, 1977. 

Issleib, K., Dopfer, K.-P, and Balszuweit, A., Contribution to the synthesis of a-aminoalkane phosphonic acid dialkyl esters, Z. Anorg. Allg. Chem., 444,249, 1978. 

Some new bactericidal and fungicidal derivatives of purine and pyrazolo[l,2,4]triazine have been synthesized by the reaction of 4-arylidene-2-phenyl-S-oxazolones with different nucleophilic reagents <99IJC(B)445>. A variety of pyrazolo[3,2-c][l,2,4]-triazin-3-yl 55, 59 and l,2,4-triazolo[33-c][l,2,4]-triazin-3-yl-phosphonic acid dialkyl esters 56, 60 have been synthesized from diazobetaines of pyrazoles 57 and ttiazoles 58 and monocarbanions of certain phosphonates, respectively <99H513>. 

The precursors for these Horner-Wadsworth-Emmons reagents are /f-ketophosphomc acid dialkyl esters or a-(alkoxycarbonyl)phosphonic acid dialkyl esters. The first type of compound, i.e., a /3-ketophosphonic acid dialkyl ester is available, for example, by acylation of a metalated phosphonic acid ester (Figure 6.48). The second type of compound, i.e., an a-(alkoxycarbonyl)phosphonic acid dialkyl ester, can be conveniently obtained via the Arbuzov reaction (Figure 11.12). 

Condensations between aldehydes and metalated phosphonic acid dialkyl esters other than those mentioned previously are also referred to as Homer-Wadsworth-Emmons reactions. Nevertheless, in these esters, too, the carbanionic center carries a substituent with a pi electron withdrawing group, for example, an alkenyl group, a polyene or a C=N group. The Homer-Wadsworth-Emmons reactions of these reagents are also stereoselective and form the new C=C double bond /ra/ ,v-selectively. 

Horner-Wadsworth-Emmons reactions are C—C-forming condensation reactions between the Li, Na, or K salt of a /J-keto- or an -(alkoxycarbonyl)phosphonic acid dialkyl ester and a carbonyl compound (cf. Figure 4.41). These reactions furnish a,f)-unsaturated ketones or a j8-unsaturated esters, respectively, as the desired products and a phosphoric acid diester anion as a water-soluble by-product. In general, starting from aldehydes, the desired compounds are produced fraus-selectively or in the case of olefins with trisubstituted C—C double bonds -selectively. 

McKenna, C.E., Higa, M.T., Cheung. N.H., and McKenna, M.C., The facile dealkylation of phosphonic acid dialkyl esters by bromotrimethylsilane. Tetrahedron Lett., 18, 155, 1977. 

Dialkoxyphosphoryl-substituted carbanions, usually generated by the reaction of methyl-substituted phosphonic acid dialkyl esters with sodium hydride, react with a variety of oxiranes to give substituted cyclopropanes in moderate to good yield. Whereas the reaction of A5-phos-phanes with oxiranes (see Section 1.2.2.1.) gives cyclopropanes under forcing reaction conditions (200 °C, 8 hours), the phosphoryl-substituted carbanions give cyclopropanes under relatively mild conditions by a similar reaction mechanism (Houben-Weyl, Vol4/3, p 138). 

It was found that lV,lV-bis-(2-hydroxyalkyl)-aminomethane phosphonic acid dialkyl esters, corresponding to compounds with formula 3, can be obtained by reacting dialkyl H-phosphonates 1 with oxazolidines 2 in the presence of an acid ion exchanger [71],... 

Phosphonic acid dialkyl esters (PAE) are a group of compounds exhibiting biological activity as herbicides, defoliants, insecticides etc. (1). They are relatively large and non-rigid molecules described by a general formula RP(0)(0R ). For most PAE, molecular shape and... 

Plumb, J.B., Obrycki, R., and Griffith, C.E., Phosphonic acids and esters. XVI. Formation of dialkyl phenylphosphonates by the photoinitiated phenylation of trialkyl phosphites, ]. Org. Chem., 31, 2455, 1966. 

Dialkyl (bromodifluoromethyl)phosphonates react with zinc dust at room temperature to give products which may be acylated (Scheme 3). (Difluoro-methylene)bis(phosphonic acid) has been prepared by the hydrolysis of its tetrakis(trimethylsilyl) ester its sodium salts are stable to strong alkali. Scheme 4 outlines a synthesis, starting from the anion of monofluoromethylenebis-(phosphonic acid) tetraisopropyl ester, of (l-fluoroethenyl)phosphonates, hydrogenation of which gives (l-fluoroalkyl)phosphonates. ... 

C H NMR data for some salts of H-phosphonic acid monoalkyl esters with general formula [RO-PHOO] A" ". Chemical shift for the a-carbon atoms of the corresponding dialkyl H-phosphonates are given in parentheses... 

A pletliora of different SA systems have been reported in tire literature. Examples include organosilanes on hydroxylated surfaces, alkanetliiols on gold, silver, copper and platinum, dialkyl disulphides on gold, alcohols and amines on platinum and carboxyl acids on aluminium oxide and silver. Some examples and references can be found in [123]. More recently also phosphonic and phosphoric esters on aluminium oxides have been reported [124, 125]. Only a small selection out of tliis number of SA systems can be presented here and properties such as kinetics, tliennal, chemical and mechanical stability are briefly presented for alkanetliiols on gold as an example. 

Trialkyl esters of phosphonic acid exist ia two structurally isomeric forms. The trialkylphosphites, P(OR)2, are isomers of the more stable phosphonates, 0=PR(0R)2, and the former may be rearranged to resemble the latter with catalytic quantities of alkylating agent. The dialkyl alkylphosphonates are used as flame retardants, plasticizers, and iatermediates. The MichaeUs-Arbusov reaction may be used for a variety of compound types, including mono- and diphosphites having aryl as weU as alkyl substituents (22). Triaryl phosphites do not readily undergo the MichaeUs-Arbusov reaction, although there are a few special cases. 

Two preparations of diesters of phosphonous acid have been reported, - One of these, which claims to be the first preparation of these derivatives, involves the reaction of ammonium hypophosphite with triaikylsilylamines to give bis(trialkylsilyl) esters (127) in excellent yield. These compounds are extremely reactive, e.g. they are spontaneously inflammable in air. Dialkyl phosphonites (128) have also been prepared by the reduction of... 

The reaction is performed most simply by the addition of the propargylic alcohol to a solution of the phosphorus halide. Rearrangement of the phosphorus ester proceeds at ambient temperature or with mild heating. When phosphorus trihalides are used, the product can be isolated as the phosphonic dichloride.168169 Aqueous workup provides the phosphonic acid.162 In most instances, however, a dialkyl phosphorochloridite with only a single halogen on phosphorus available for reaction with alcohol has been used.165 170 174... 

Pudovik AN (1952) Addition of dialkyl phosphites to imines. New method of synthesis of esters of amino phosphonic acids. Dokl Akad Nauk SSSR 83 865-868... 

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 ... 

In contrast to these results, bromo-trimethylsilane (527) has only ester cleaving properties referring to dialkyl phosphonates (Scheme 85). Via this reagent a great variety of substituted phosphonic acids can be prepared in hitherto unknown yields. 

R-P(0H)2[R-P(0)(H)0H] Phosphonous acid (alkylphosphonous acid esters dialkyl alkylphosphonite) phosphonige Satire... 

The LDA catalyzed rearrangement of dialkyl aryl phosphates (99) to dialkyl (2-hydroxyaryl)- phosphonates has been known for some time and the use of the di-tert-butyl esters, now reported, offers advantages in the ease of preparation of the respective free (2-hydroxyaryl)phosphonic acids. The sequence (Scheme 7) has also been extended to include further phosphorylation and rearrangement steps to yield the 2,6-bis(dialkoxyphosphinyl)phenols (100). ... 

Both (122) and (123) can be converted into the free acids following initial reaction with Me SiBr. An alternative approach to the (l,2-difluoroethenediyl)bis-(phosphonic acid) esters (123) consists in initial interaction of trifluorovinylmagnesium bromide and a suitable dialkyl chlorophosphite subsequent oxidation of the products with Mn02 or Se02 yields dialkyl... 

Hydroxyalkyl)phosphonic acids, and also the related phosphinic acids, are normally obtained from hydrogen phosphonates and aldehydes or ketones. The reactions between perfluoroacetone and mixed dialkyl hydrogen phosphonates are noteworthy in that the expected products (129) may be accompanied by the phosphoric triesters (130). Trimethylsilyl alkylene P(III) triesters (131) are also useful starting materials when acted upon by aromatic aldehydes or by (1-oxoalkyl)phosphonic acid esters, the initial... 

Diaryl methyl- and benzyl-phosphonates are conveniently prepared in high yields by heating mixtures of triaryl phosphites, methanol or benzyl alcohol, and a trace of methyl or benzyl halide. In a reaction that is usefully complementary to the previously reported formation of pyridine-2-phosphonic acid derivatives from sodium dialkyl phosphonates and //-methoxypyridinium compounds ( Organophosphorus Chemistry , Vol. 7, p. 111), N-triphenylmethylpyridinium tetrafluoroborate affords the pyridine-4-phosphonic dialkyl ester when heated with sodium dialkyl phosphonates. ... 

Brel, V.K., Abramkin, E.V, and Martynov, I.V, [2 -I- 4]-Cycloaddition of tetracyanoethylene with dialkyl esters of 3-dialkylamino-l,3-alkadiene-2-phosphonic acid, Izv. Akad. Nauk SSSR, Ser Khim., 2843, 1989 Bull. Acad. Sci. USSR, Div. Chem. Sci. (Engl. Transl.), 2607, 1989. 

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