Phosphonic esters, cyclic

The cyclic phosphonate ester analog of the cyclic transition state. Antibodies raised against this phosphonate ester act as enzymes they are catalysts that markedly accelerate the rate of ester hydrolysis. 

Various cyclic phosphonate esters 36 and 37 have been described previously as products from the HHT reaction of 25 with the appropriate cyclic phosphite. A complementary method has also been developed from the V-protected phosphonyl chloride 84, which was readily prepared from the corresponding phosphonic acid 83. Subsequent reaction of 84 with the appropriate diol produced the cyclic phosphonate esters 85 (63). Higher homologs of 85 have also been prepared from the analogous propane or butane diols. 

Two papers describe the hydrophosphonation of unsaturated cyclic hydrocarbons. With dialkyl phosphonates, cycloocta-1,5-diene affords the phosphonate esters (66) but in the presence of strong acids, or when using the moderately strong l PtOXDH itself, the monocyclic esters (67) are also formed. Cyclododeca-1,5,9-triene affords a mixture of polycyclic... 

Derivatives of the general formula (7) in Table 6 have been successfully used as probases and their properties in this context are being further explored. In common with the azobenzenes and ethenetetracarboxylate esters, the fluoren-9-ylidene derivatives usually display two reversible one-electron peaks in cyclic voltammetric experiments. Although disproportionation is possible (cf. Scheme 12) it is the dianions which are the effective bases. It was shown early on that the radical-anions of such derivatives are long-lived in relatively acidic conditions (e.g. in DMF solution the first reduction peak of Ph C -.QCN) remains reversible in the presence of a 570-fold molar excess of acetic acid, at 0.1 V s ). Even the dianions are relatively weak bases, useful mainly for ylid formation from phosphonium and sulphonium salts (pKj s 11-15) they are not sufficiently basic to effect the Wittig-Homer reaction which involves deprotonation of phosphonate esters... 

Russian workers83 84 have synthesized a series of phosphorus-containing crowns utilizing O—P—O bonds in the macrocycle, i.e. cyclic phosphonate esters (7). One of these is claimed to have been prepared in 40% yield (equation 29). 

Five-membered cyclic phosphate and phosphonate esters have rates of hydrolysis orders of magnitude greater than those of the corresponding acyclic esters (6), therefore such five-membered cyclic esters are undesirable components if the oligomers are used as flame retardants. 

Derivatives of phosphonic acids, RP==O(0H)2, can be prepared by several different oxidative methods. Primary phosphines RPH2 are oxidized to phosphonic acids by hydrogen peroxide or by sulfur dioxide thus, phenylphosphine gave benzenephosphonic acid (96%) on reaction with sulfur dioxide at room temperature in a sealed tube. Phosphinic acids, RI sO(OH)H, can also be oxidized to the corresponding phosphonic acids with hydrogen peroxide. Ozone oxidized the dioxaphosphorane (54) to the phosphonic ester in 73% yield. Ozone is also capable of stereospecific oxidation of phosphite esters to phosphates. For example, the cyclic phosphite (SS) was oxidized to the phosphate (56) with retention of configuration. Peroxy acids and selenium dioxide are other common oxidants for phosphite esters. 

The mass spectra of cyclic phosphonate esters (114) and new 3-methyl-2(3H)-benzoxazolone hydrazone phosphorylated compounds and substi-... 

Gurevich, P.A., Shelepova, N.L, and Razumov, A.L, Synthesis of cyclic alkylene acetals of phosphinyl-acetaldehydes, Zh. Obshch. Khim., 38, 1905, 1968 J. Gen. Chem. USSR (Engl. Transl.), 38, 1854, 1968. Cooper, D., and Trippett, S., Some rearrangements of unsaturated phosphonate esters, J. Chem. Soc., Perkin Trans. 1, 2127, 1981. 

Other Studies. - The P NMR chemical shifts of alcohols, carboxylic acids and phenols phosphitylated with 2-chloro-4,4,5,5-tetramethyl-dioxaphospholane have been correlated with substituent effects of phenols. P NMR spectroscopy has also been used to study activation pathways of aryl H-phosphonate ester condensation reactions, the conversion of allenyl and divinyl phosphines to 1- and 2-phosphadienes, the reaction of tetraphosphorus decasulfide with dialkyl disulfides, the reaction of phosphine with cyclic olefins, the chemical shift tensors of powder samples of phosphole derivatives, the reactions of alcohols and mercaptans with tetraphosphorus trichalcogen diiodides, the structure of aminomethanebisphosphonic acids, and reactions of 00-di-(2-ethylhexyl)dithiophosphoric acids. ... 

Solvolysis of the a-haloalkylphosphinic esters (97) and (98) with methoxide ion in methanol leads to the rearranged phosphonate esters (99) and (100). The formation of these products can be readily accommodated in terms of a cyclic phosphinate intermediate. 

Related reactions in the oxygen series were first observed only recently as complications in Michaelis-Arbuzov reactions. The 2-halo-alkyl phosphate and phosphonate esters which occur as intermediates in the Michaelis-Arbuzov reaction of certain cyclic phosphites and phos-phonites (cf. Section II-A-1) undergo an internal alkyl exchange reaction (eq. 4) (176). Although reaction of 8-bromoethyl acetate with triethyl phosphite is said to furnish the expected product, diethyl fi-acetoxyethylphosphonate, in 28% yield (220), reaction of this same alkyl halide with dimethyl phenylphosphonite (129) gave the expected methyl phenyl(/9-acetoxyethyl)phosphinate in not greater than 5% yield (eq. 6). Instead, the major products were d-acetoxyethyl phenyl-(methyl)phosphinate (60%) (12) and a mixture of ethylene bi [phenyl-(methyl)phosphinate], [CH20P(0)(Me)Ph]2, (13) and an, ester of... 

It is evident that the interaction of a phosphorus(III) triester and the alkylating species RX can be pictured as an S 2 process (reaction 2) or, for those alkylating reagents capable of forming a carbocation, as an S l process (reaction 3). Several reactions testify to the importance of carbocationic carbon for the Michaelis-Arbuzov reaction in pursuance of its normal course they include the ease of reaction of cyclopropene dihalides, already encountered, and the ready formation of complexes with species having particularly weakly nucleophilic counter ions. Phosphonic acid formation also takes place with cyclic azonium salts and related ions. 9-Chloroacridine reacts with triethyl phosphite to afford a product thought to be the bisphosphonic acid ester 49 The related phosphonic esters 51 are obtainable when the onium salts 50 (X = NH, NR, O or S) are treated with trimethyl... 

When NaOMe was employed as catalyst in the initial reaction, the formation of 262 was accompanied by that of significant amounts of the 3-hydroxy-l,2-oxaphosph(V)olanes 263, again as mixtures of diastereoisomers. The latter are also obtained through the tri-ethylamine-catalysed intramolecular transesterification of the linear esters 262 Mixtures of linear and cyclic acylated phosphonic esters, e.g. the acetates of 262 and 263, result when 4-acetyloxybutan-2-one is acted upon by a dialkyl hydrogenphosphonate". ... 

Rare examples of normal Michaelis-Becker reactions which involve co-chloroalkanal diethyl acetals are to be found, and although the formation of dialkyl acylphosphonates from sodium dialkyl phosphites and, for example, benzoyl chloride, is to be observed at -85 °C, the system is further complicated, even at -10 °C, by further addition steps followed by rearrangements which would seem to render the process of little value for the synthesis of oxoalkyl phosphonic esters On the other hand, in a more detailed and systematic study of reactions between sodium dialkyl phosphites, (RO)2PONa(R = Et or Bu), and the ketones R CO(CH2) Cl, Sturtz and others have observed the formation of epoxides when n = 1 and (1-hydroxy alk-2-enyl)phosphonic diesters when n = 2(R = Me or Pr ), according to the displacement in 532, and of derivatives of tetrahydrofuran or tetrahy-dropyran, according to 533 n = 3 or 4) when R = Et, the formation of the cyclic ethers was accompanied by low yields of the expected (oxoalkyl)phosphonic diester, but otherwise the latter were isolated as a single product only for R = Me, n = 5, and R = Et or Pr when n = 2. 

The well-known retro-Diels-Alder expulsion of SO2 and liberation of buta-1,3-diene when their adduct is heated has analogies in the phosphorus field. Flash thermolyses of the cyclic phosphonic ester 493 (R = OMe) and of the phosphinic ester 493 (R = 2,4,6-trimethylphenyl) afford buta-1,3-diene and the highly reactive metaphosphate 494 (R = OMe) or metaphosphonate 494 (R = 2,4,6-trimethylphenyl) species. The elimination of phenylmetaphosphonate or an analogous species was observed during the thermolysis of the 1,3,2-dioxaphospholanes 495 [Ar = (a) Ph or (b) (l,l -biphenyl)-2-yl or (c) 2,4,6-tri-tcrt-butylphenyl ] at 700-800 °C here the respective metaphosphonates were characterized through the formation of the indicated known products. The compound 496 (Ar = Ph)... 

Compounds which have been studied in the phosphonic group included an a-aminophosphonic acid and ester, a thiamin betaine, a cyclopropane-phosphonate, a cyclic ester (82), and two phosphazenes. ... 

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