Vinyl phosphate

Coupling of Vinyl Phosphonates and Triflates to Organometallic Reagents - vinyl phosphates review Synthesis 1992, 333,... 

Vinyl Phosphates. Dichlorvos [62-73-7] 0,0-dimethyl 0-(2,2-dichloroviayl) phosphate, (CH20)2P(0)0CH=CCl2 (bp 140°C at 27 kPa, d 1.314, vp 1.6 Pa at 20°C), is soluble ia water to about 10 g/L. The half-hfe ia water is 8 h. The rat oral LD qS are 80, 56 mg/kg. Dichlorvos is used ia aerosols and sugar baits to control flies and mosquitoes. Slow release formulations have been used ia plastic strips and pet collars to control animal ectoparasites. 

Poly(vinyl nitrate) has been prepared and studied for use in explosives and rocket fuel (104,105). Poly(vinyl alcohol) and sulfur trioxide react to produce poly(vinyl sulfate) (106—111). Poly(vinyl alkane sulfonate)s have been prepared from poly(vinyl alcohol) and alkanesulfonyl chlorides (112—114). In the presence of urea, poly(vinyl alcohol) and phosphoms pentoxide (115) or phosphoric acid (116,117) yield poly(vinyl phosphate)s. 

Diazoalkanes add readily to the double bond of esters of vinylphosphonic acid, giving the pyrazoline derivatives (100), which can lose nitrogen to give esters of cyclopropylphosphonic acids. In a similar reaction, acyl-phosphonic acid esters (101) were converted to epoxy-derivatives (102). A -Phenylsydnone adds to diethyl prop-l-ynephosphonate, giving the pyra-zole (103). The addition of cyclopentadiene to dimethyl vinyl phosphate leads to an exojendo quotient of 1.2, but with hexachlorocyclopentadiene only e/ii/o-isomer is formed. ... 

Phosphate groups can also be removed by dissolving-metal reduction. Reductive removal of vinyl phosphate groups is one method for conversion of a carbonyl compound to an alkene.224 (See Section 5.7.2 for other methods.) The required vinyl phosphate esters are obtained by phosphorylation of the enolate with diethyl phospho-rochloridate or /V A /V -tetramethyldiamidophosphorochloridate.225... 

Similarly, nickel catalysis permits the extension of cross coupling to vinyl phosphates, which are in some cases more readily obtained and handled than vinyl triflates.273... 

An unusual two-component domino Michael/aldol process was described by Tomioka and coworkers in which the initiating step is the formation of an a-lithiated vinyl-phosphine oxide [28] or vinyl phosphate [29]. 

Hampton, A., Perini, F., and Harper, P.J., Derivatives of phosphonate and vinyl phosphate analogs of D-ribose 5-phosphate, Carbohydr. Res., 37, 359,... 

Plant. In plants, mevinphos is hydrolyzed to phosphoric acid dimethyl ester, phosphoric acid, and other less toxic compounds (Hartley and Kidd, 1987). In one day, the compound is almost completely degraded in plants (Cremlyn, 1991). Casida et al. (1956) proposed two degradative pathways of mevinphos in bean plants and cabbage. In the first degradative pathway, cleavage of the vinyl phosphate bond affords methylacetoacetate and acetoacetic acid, which may be precursors to the formation of the end products dimethyl phosphoric acid, methanol, acetone, and carbon dioxide. In the other degradative pathway, direct hydrolysis of the carboxylic ester would yield vinyl phosphates as intermediates. The half-life of mevinphos in bean plants was 0.5 d (Casida et ah, 1956). In alfalfa, the half-life was 17 h (Huddelston and Gyrisco, 1961). 

Dichloroethane, 1,1-Dichloroethylene, trans-, 2-Dichloroethylene, Tetrachloroethylene, 1,1,1-Trichloroethane, 1,1,2-Trichloroethane, Trichloroethylene Vinyl phosphates, see Mevinphos Vinyltoluene, see Styrene... 

The etiolate intermediate, generated by the addition of higher-order cyanocuprates to enones, has been trapped with several electrophiles. Thus the addition of trimethylsilyl chloride, diethyl or diphenyl phosphorochloridate and iV-phenyltrifluoro methane-sulphonamide affords the corresponding vinyl silyl ethers, vinyl phosphates and vinyltri-flates. " ... 

The 2-formyl-ip-methylcarbapenem 62 has been obtained in five steps from a readily available P-lactam in 23-26% overall yield <98MI1294>. Suzuki-Miyaura cross-coupling of aiylboronic acids and vinyl triflates is a convenient route to 2-aiylcarbapenems on a small scale but may present problems on a large scale. Vinyl phosphates, mesylates or tosylates are convenient alternatives to triflates <9981471>. Radical cyclizations of readily available enyne-2-azetidinones (e.g., 63) with a tin hydride, RjSnH, provides a route to the... 

Dimethyl S-(l,2-dicarbethoxy-ethyl) phosphorodithioate, AS73 0,0-Dimethy) 0-(2,2-dichi oro-vinyl) phosphate, AC96... 

In spite of many previous studies on the mechanisms by which trialkyl phosphites interact with a -halogenocarbonyl compounds, the reactive intermediates which lead to ketophosphonate (Arbuzov reaction) and to vinyl phosphate (Perkow reaction) have in no cases been clearly identified. It is generally believed (JL), however, that the Arbuzov product 4 results from initial attack by phosphorus at the cf-carbon atom, whereas the Perkow product 7 is formed by initial attack at the carbonyl carbon atom, followed by migration of phosphorus from carbon to oxygen (Scheme 1). 

To obtain more information on the nature of the quasiphosphonium intermediates involved in these systems we have studied the reactions gf sterically hindered neopentyl esters by means of 1P nmr spectroscopy. Trineopentyl phosphite and a-bromoacetophenone gave rise to a peak at +41 ppm due to the ketophosphonium intermediate 3 (R = Me.CCH, R = Ph X = Br ) within half an hour of mixingJthe reactants in acetone-dfi at 27 °C ( p nmr shifts are relative to 85% H-PO. down-field positive). Peaks due to the ketophospnonate 4 +19 ppm and the vinyl phosphate 7 (-7 ppm) were also observed (compound 4 and 7 have satisfactory elemental analysis and spectroscopic data ). The concentration of the intermediate reached a maximum after about two hours when it was precipitated from acetone solution by the addition of anhydrous ether to give white crystals of trineopentyloxy (phenacyl)phosphonium bromide, identified by elemental analysis and nmr spectroscopy ( XP 6+41, in CDCl ). When redissolved in acetone-dg, deuterochloroform, acetic acid, or acetic acid-acetone mixtures, the intermediate decomposed to yield keto-phosphonate 4 but none of the vinyl phosphate 6 (Perkow product). Nor was the course of reaction affected by the addition of chloride ion or of a-chloro-acetophenone in acetonitrile. 

A proposal (3) that vinyl phosphate might be formed from the ketophosphonium intermediate, after rearrangement via a four-membered cyclic phosphorane 8 is therefore excluded by our results under these reaction conditions. 

We also found that the vinyl phosphate was the major reaction product in the initial stages of the reaction of trineopentyl phosphite with a-bromoaceto-phenone in acetone-dfi, but that the product ratio changed in favour orthe ketophosphonate as the reaction proceeded. The results are consistent with a reaction scheme in which the ketophosphonium and vinyl-oxyphosphonium intermediates are formed by parallel pathways, either directly from the reactants, of from a common first intermediate X and in the light of our previous kinetic studies 2) the latter is indicated (Scheme 3). 

By carrying out the reaction of trineopentyl phosphite with a-bromoacetophenone in the presence of acetic acid (10% in acetone-d ) we have also obtained evidence for the transient existence of the vinyloxy-phosphonium species. Under these conditions, we observed the., rapid appearance of three transient intermediates ( 1Pcx+92, +40, and -7.3 ppm), although vinyl phosphate was the almost exclusive final product. The peak at -7.3 ppm disappeared most rapidly, with the simultaneous development of a corresponding peak at -7.2 ppm due to vinyl phosphate, and is tentatively assigned to the vinyloxyphosphonium bromide. Jt is known that tetraalkoxyphosphonium ions have XP chemical shifts which are not far removed from those of the corresponding phosphate esters ( ) ... 

Chemical Name dimethyl( )-l-methyl-2-(l-phenyl-ethoxycarbonyl)vinyl phosphate... 

REDUCTIVE CLEAVAGE OF VINYL PHOSPHATES PREPARATION OF 17 i-tert-BUTOXY-5a-ANDROST-2-ENE... 

A practical synthesis of 1,3-OX AZEPINES VIA PHOTOISOMERIZATION OF HETERO AROMATIC V-OXIDES is illustrated for 3,1-BENZOXAZEPINE. A hydroboration procedure for the synthesis of PERHYDRO-9b-BORAPHENALENE AND PERHYDRO-9b-PHEN-ALENOL illustrates beautifully the power of this methodology in the construction of polycyclic substances. The conversion of LIMONENE TO p-MENTH-8-EN-YL METHYL ETHER demonstrates a regio-and chemoselective method for the PHOTOPROTONATION OF CYCLOALKENES. An efficient method for the conversion of a ketone to an olefin involves REDUCTIVE CLEAVAGE OF VINYL PHOSPHATES. A mild method for the conversion of a ketone into the corresponding trimethylsiloxy enol ether using trimethylsilyl acetate is shownforthe synthesis of (Z)-3-TRIMETHYLSILOXY-2-PENTENE. 

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