Diethyl vinylphosphonate

This regioselectivity is practically not influenced by the nature of subsituent R. 3,5-Disubstituted isoxazolines are the sole or main products in [3 + 2] cycloaddition reactions of nitrile oxides with various monosubstituted ethylenes such as allylbenzene (99), methyl acrylate (105), acrylonitrile (105, 168), vinyl acetate (168) and diethyl vinylphosphonate (169). This is also the case for phenyl vinyl selenide (170), though subsequent oxidation—elimination leads to 3-substituted isoxazoles in a one-pot, two-step transformation. 1,1-Disubstituted ethylenes such as 2-methylene-1 -phenyl-1,3-butanedione, 2-methylene-1,3-diphenyl- 1,3-propa-nedione, 2-methylene-3-oxo-3-phenylpropanoates (171), 2-methylene-1,3-dichlo-ropropane, 2-methylenepropane-l,3-diol (172) and l,l-bis(diethoxyphosphoryl) ethylene (173) give the corresponding 3-R-5,5-disubstituted 4,5-dihydrooxazoles. 

Several addition reactions of mono- and di-enephosphonates have been reported. Diethyl vinylphosphonate reacts at 100 °C with cyclohexanone pyrrolidenamine in a stepwise fashion. Hydrolysis of the initial adduct yields the ketophosphonate (143) but further reaction of the adduct in a Mannich-type process can yield, ultimately, the cyclobutenylphosphonate (144).112 Diethyl butadienephosphonate condenses... 

Phosphonates which are isosteric with RNA and DNA derivatives are potentially of great biological interest. It seemed to us88 that the addition of the radical 90 to diethyl-vinylphosphonate 111 would afford 112, easily reducible to 113, or by oxidation and elimination converted to the vinyl-... 

Kabanov et al. cross-linked a copolymer of diethyl vinylphosphonate and acrylic acid with V,V -methylenediacrylamide in the presence of metal ions [5,6]. Scheme 9.3 illustrates the possible coordination of Cu(II) with the functional groups of the adsorbent. The obtained resins were characterised by IR and H-NMR spectroscopy, in addition to the metal adsorption test. 

Scheme 9.3. Interaction between Cu(II) and a polymer of diethyl vinylphosphonate and acrylic acid.

Alkenyl, Alkynyl, Aryl and Heteroaryl Acids. Treatment of readily accessible (E)- and (Z)-alkyl and aryl substituted vinyl boronates (196) with triethyl phosphite in the presence of lead diacetate results in their stereospecific transformation into (E)- and (Z)-vinylphosphonates (197) (Scheme 53). ° Palladium acetate catalysed Mizoroki-Heck reaction of arylboronic acids (198) with diethyl vinylphosphonates (199) is an effective synthetic approach to... 

The action of an aldehyde RCHO upon diethyl vinylphosphonate... 

The addition of copper(I) reagents to diethyl 1-alkynylphosphonates and trapping of the resulting l-copper(I)vinylphosphonates with molecular iodine at low temperature afford diethyl a-iodovinylphosphonates in excellent overall yields (97-98%) The oc-deprotonation of diethyl vinylphosphonates with strong bases and subsequent treatment with iodine has also been reported (Scheme 3.34) °... 

The halohydroxylation method has been developed for exploiting the reactivity of the double bond present in dialkyl vinyl- and propenylphosphonates. Preparation of the halohydrins of diethyl vinylphosphonate failed using NBS or NBA. Treatment of diethyl vinylphosphonate on large scale with NaOCl or NaOBr in aqueous medium at pH < 3 gives the halohydrins with the hydroxyl group in the P-position (anti-Markovnikoff addition) with 95% or 65-85% purity, respectively (Scheme 4.9). As a consequence of the acid conditions, the preparation of halohydrins is generally accompanied by the formation of undesired diethyl 1,2-dihalogenophosphonates. ... 

A vai iety of diethyl vinylphosphonates have been oxidized in moderate to good yields (19-84%) using dioxirane generated in situ from buffered monopersulfate (Oxone ) and a ketone in a two-phase (ClECb/lEO) reaction mixture.Because of the pH dependence of dioxirane stability, the process needs an accurate control of the pH at 7.4. However, the reaction is often very sluggish and requires regular addition of fresh portions of oxone and lengthy reaction times. 

The palladium-catalyzed arylation of diethyl vinylphosphonate using aryl bromides has been reported. The experimental procedure is simple, and the yields are moderate to good (Scheme 5.58). For example, with para-bromobenzaldehyde in MeCN at lOO C, diethyl para-tormyl-trans-styrylphosphonate is formed exclusively in 60% yield. ... 

A number of addition reactions have been reported. For example, diethyl vinylphosphonate reacts with the enolates of cyclohexanone and 2-methylcyclohexanone, generated in situ by the treatment of silyl enol ethers with benzyltrimethylammonium fluoride, to give the corresponding Michael adducts in 31% and 44% yields, respectively. ... 

In the presence of EtONa/EtOH, tetraethyl methylenediphosphonate adds to unsaturated electrophilic compounds, methyl acrylate and diethyl vinylphosphonate. Only products of addition to one molecule of the unsatiuated compound are obtained. ... 

Addition of ethyl 2-pyridylacetate to diethyl vinylphosphonate without solvent using EtONa as catalyst produces diethyl 3-(ethoxycarbonyl)-3-(2-pyridyl)propylphosphonate in 60% yield. Acid hydrolysis with 10 M HCl followed by decarboxylation of the product gives the 3-(2-pyridyl)propylphosphonic acid in 50% yield (Scheme 8.60). 

Addition of diethyl malonate to diethyl vinylphosphonate,tetraethyl ethenylidenediphos-phonate/ and diethyl l-ethenylidene-Z-oxoalkylphosphonates nnder basic conditions has been described. The em-diphosphonate resulting from the addition of diethyl malonate to tetraethyl ethenylidenediphosphonate in the presence of EtONa/EtOH after saponification with KOH in aqueous THF and acidihcation is decarboxylated to give the tetraethyl 3-(hydroxycarbonyl)-l,l-propylidenediphosphonate in 65% yield (Scheme 8.61... 

Michael addition of metallated camphor derivatives of diethyl aminomethylphosphonate to diethyl vinylphosphonate followed by hydrolysis with 90% aqueous AcOH leads in 73% yield and high diastereoselectivity to tetraethyl A-acetyl 2-amino-l,3-propylenediphosphonate, a phosphonic analogue of glutaric acid (Scheme 8.8V). No racemization occurs under the hydrolysis conditions Similarly, methyl acrylate, after hydrolysis of diastereomerically pure adduct, leads to the phosphonic analogue of pyroglutamic acid further reduced with I.iBlI,/BF. t,() to the phosphoproline diethylester in 61% yield (Scheme 8.87). ... 

The radical 7.36 produced by addition of an alkyl radical to diethyl vinylphosphonate 735 will be very similarly stabilised no matter what the alkyl group R is, yet the relative rates for the different radicals are in the order Bu > Pr > Et > Me.990 This is opposite to the usual expectation that the more stable the radical the less reactive it is. The simplest explanation is that the more substituted radical has the higher-energy SOMO, closer in energy to the LUMO of the vinylphosphonate 7.35, which, because it is a Z-substituted alkene, will be low in energy. 

Early reports on the addition of chlorine or bromine to diethyl vinylphosphonate (133 R = EtO) and to vinylphosphonic dichloride (133 R = Cl) " suggest a lack of predictability even in such simple cases. The addition of bromine in chloroform to 133 (R = EtO) leads to 134 with smaller amounts of 135 chlorination of the same ester in CCI4 also leads to a mixture of the two types, in this case in roughly equal amounts. On the other hand, the bromination of vinylphosphonic dichloride yields (l,2-dibromoethyl)phospho-nic dichloride (135 R = Cl, X = Br), which is sufficiently stable to allow hydrolysis to (1,2-dibromoethyl)phosphonic acid. The ready loss of HBr followed the addition of 2 mol of bromine to phenyl(4-phenylbuta-1,3-dienyl)phosphinic acid the product consisted almost exclusively of Ph(PhC4H3Br3)P02tf... 

R = H), derived from (+)-oxopinic acid, and (aminomethyl)phosphonic acid diethyl ester, was alkylated in the usual way and the products hydrolysed to give the (S)-( 1-aminoalkyl)phosphonic diesters with 15. 62, 93, and 92% e.e. for R = Me, Et. Bn. and allyl. The reaction between (347 R = Li) and diethyl vinylphosphonate gave the (lS)-(347 R = CH2CH2P02Et2) which was acidolysed ( aqueous acetic acid) to... 

It is worthy of note that when diethyl vinylphosphonate is treated with CHCI3/HO in the presence of a phosphonium or ammonium salt or dibenzo-18-crown-6, the... 

DuBois et al [4] reported the synthesis of phosphorus-containing dendrimers using a sequential addition of diethyl vinylphosphonate to primary phosphanes... 

The MBH reactions of diethyl vinylphosphonate dates back to 1990, and they present similar reactivities to alkyl acrylates. It was found that diethyl vinylphosphonate can be coupled with various aliphatic aldehydes in the presence of DABCO to give moderate to high yields of the corresponding a-hydroxyalkyl phosphonates 85. However, this approach was not effective for aqueous formaldehyde and polyoxymethylene, and the corresponding a-hydroxymethyl phosphonates 87 can only be obtained through a Wittig Horner-type reaction from tetraethyl methylenediphosphonate 86 and formaldehyde (30% aq.) in the presence of a weak base K2CO3 (6-8 m) (Scheme 1.42). 

Aldehydes have been the primary source of eleetrophiles since the initial MBH reaetion was explored. On the basis of both eleetronic and steric considerations, they are much more active than simple ketones. Formaldehyde ean be employed as an aqueous solution (formahn), the polymer (paraformaldehyde), as a solution of the monomer in an organie solvent or as a hemiacetal (Scheme 1.43). Similar results were obtained in eouplings of aldehydes with acrylonitrile, methyl vinyl ketone and phenyl vinyl sulfone. However, aqueous formaldehyde can not react with diethyl vinylphosphonate. ... 

Polymerization of diallg l vinylphosphonate monomers was nevertheless efficiently carried out in the presence of lanthanide derivatives and especially cyclopentadienyl lanthanide complexes, used both as initiators and catalysts. Very recently, Shen et al performed the synthesis of poly (diethyl vinylphosphonate) using a lanthanide tris(borohydride) below 50 °C. The authors showed that the polymerization eould be controlled and proceeds under pseudo-first-order kinetics, giving rise to high molecular weight polymers, i.e. ranging from 20 to 40 kDa with molecular weight dispersity below 1.7. 

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