Phosphonates, additions

Although transition metal-mediated P-H addition across ordinary alkenes proceeds well only with five-membered cyclic hydrogen phosphonates, addition across the olefinic linkage of a,P-unsaturated compounds occurs readily with a range of phosphorus species and catalytic agents. Of particular note are the reaction systems involving platinum,96-107 palladium,108-115 and the lanthanides.116-122... 

Conjugated dienes undergo hydroperfluoroalkylation with perfluoroalkyl iodides and zinc in the presence of titanium catalysts 02 Yields are moderate to good (52-74%) but stereoselectivity is low. From allylic halides functionalized on the a-vinylic position (TMS, carboxylate, phosphonate), additions to terminal alkynes provide functional dienes, used in further synthetic reactions leading to lactones and carboxylic or phosphonic esters.228... 

The Wittig reaction wherein a phosphonate is substituted for the more traditional phosphonium salt is called either the Wittig-Horner [8] or Wittig-Emmons [9] reaction. The synthesis of alkenes via base catalyzed phosphonate addition to an aldehyde or ketone has been accomplished under phase transfer conditions [10—13]. 

Gan H, Takeuchi ES (2002) Phosphonate additives for nonaqueous electrolyte in rechargeable electrochemical cells. US Patent 6,495,285 B2. Accessed 17 Dec 2002... 

The reaction of perfluoroalkyl iodides with alkenes affords the perfluoro-alkylated alkyl iodides 931. Q.a-Difluoro-functionalized phosphonates are prepared by the addition of the iododifluoromethylphosphonate (932) at room temperature[778], A one-electron transfer-initiated radical mechanism has been proposed for the addition reaction. Addition to alkynes affords 1-perfluoro-alkyl-2-iodoalkenes (933)[779-781]. The fluorine-containing oxirane 934 is obtained by the reaction of allyl aicohol[782]. Under a CO atmosphere, the carbocarbonylation of the alkenol 935 and the alkynol 937 takes place with perfluoroalkyl iodides to give the fluorine-containing lactones 936 and 938[783]. 

Adducts from various quaternary salts have been isolated, in reactions with aldehydes, a-ketoaldehydes, dialkylacylphosphonates and dialkyl-phosphonates, isocyanates, isothiocyanates, and so forth (Scheme 15) (36). The ylid (11) resulting from removal of a Cj proton from 3.4-dimethyl-S-p-hydroxyethylthiazolium iodide by NEtj in DMF gives with phenylisothiocyanate the stable dipolar adduct (12) that has been identified by its NMR spectrum and reactional product, such as acid addition and thiazolidine obtention via NaBH4 reduction (Scheme 16) (35). It must be mentioned that the adduct issued from di-p-tolylcarbodiimide is separated in its halohydrogenated form. An alkaline treatment occasions an easy ring expansion into a 1,4-thiazine derivative (Scheme 17) (35). 

Halogenated All l Phosphates and Phosphonates. In this important class of additives, the halogen contributes somewhat to flame retardancy although this contribution is offset by the lower phosphoms content. The halogens reduce vapor pressure and water solubHity, thus aiding retention of these additives. Efficient manufacturing processes lead to favorable economics. 

MixedPhosphona.te Esters. Unsaturated, mixed phosphonate esters have been prepared from monoesters of 1,4-cyclohexanedimethanol and unsaturated dicarboxyhc acids. Eor example, maleic anhydride reacts with this diol to form the maleate, which is treated with benzenephosphonic acid to yield an unsaturated product. These esters have been used as flame-retardant additives for thermoplastic and thermosetting resias (97). 

The remaining 15% of the elemental P is used in P -dependent apphcations which require the element as a direct reactant. The principal products include P2S5, PCl and POCl, 2 5 hypophosphite, with much smaller amounts leading to PH, red P, phosphonates, and various other phosphoms derivatives. Pinal apphcations include flame retardants (qv), lubricant additives, insecticides, herbicides, water treatment, cleaning compounds, plastici2ers, and semiconductors (14). 

Alkyl or aryl phosphonates, which contain a carbon—phosphoms bond, are comparatively more stable. They are of interest as antiscaling additives and corrosion inhibitors for cooling towers and heat exchangers (see Dispersants Water, industrial water treatment), surfactants (qv), sequestrants, and textile-treating agents. Trialkyl phosphites are usehil as esterification (qv) reagents. 

The phosphonate esters, HP(=0(OR)2, of alkylated phenols are used extensively as lubricating-oil additives to control bearing corrosion and oxidation, and to impart antimst properties as stabilizers, as antioxidants (qv) and flame retardants in plastics, as specialty solvents, and as intermediates (see Corrosion AND corrosion control Heat stabilizers). 

Additional phosphonic acid is derived from by-product streams. In the manufacture of acid chlorides from carboxyUc acids and PCl, phosphonic acid or pyrophosphonic acid is produced, frequentiy with copious quantities of yellow polymeric LOOP. Such mixtures slowly evolve phosphine, particularly on heating, and formerly were a disposal problem. However, purification of this cmde mixture affords commercial phosphonic acid. By-product acid is also derived from the precipitate of calcium salts in the manufacture of phosphinic acid. As a consequence of the treatments of the salt with sulfuric acid, carbonate is Hberated as CO2 and phosphonic acid goes into solution. 

Organophosphoms compounds, primarily phosphonic acids, are used as sequestrants, scale inhibitors, deflocculants, or ion-control agents in oil wells, cooling-tower waters, and boiler-feed waters. Organophosphates are also used as plasticizers and flame retardants in plastics and elastomers, which accounted for 22% of PCl consumed. Phosphites, in conjunction with Hquid mixed metals, such as calcium—zinc and barium—cadmium heat stabilizers, function as antioxidants and stabilizer adjutants. In 1992, such phosphoms-based chemicals amounted to slightly more than 6% of all such plastic additives and represented 8500 t of phosphoms. Because PVC production is expected to increase, the use of phosphoms additive should increase 3% aimually through 1999. 

Phosphonic (phosphorous) acid, produced by hydrolysis of PCl, is for the most part consumed captively. It has also been offered as a flaked product and a 70 wt % solution by Rhc ne-Poulenc. Phosphonic acid is a by-product from manufacturing carboxyHc acid chlorides and alkaH peroxides. Additional by-product phosphonic acid is recovered in the manufacture of phosphinic acid. 

The anodized surface is often subjected to additional treatment before the radiation-sensitive coating is appHed. The use of aqueous sodium siUcate is well known and is claimed to improve the adhesion of diazo-based compositions ia particular (62), to reduce aluminum metal-catalyzed degradation of the coating, and to assist ia release after exposure and on development. Poly(viQyl phosphonic acid) (63) and copolymers (64) are also used. SiUcate is normally employed for negative-workiag coatings but rarely for positive ones. The latter are reported (65) to benefit from the use of potassium flu o r o zirc onate. 

The addition of phosphonate carbanions to 6-amino-5-nitrosopyrimidines may be regarded as an extension of the Timmis principle and it proceeds under mild conditions and in... 

To minimize the gradual embrittlement that can occur on aging of cyanoacrylate adhesives, plasticizers are added. Some of the materials, which have been used as plasticizers, include phthalates, phosphonates, acyl esters, succinates, and cyano-acetates. The use of allyl, methallyl, and crotyl phthalates is also claimed to improve thermal resistance properties in addition to plasticizing the adhesive [23]. 

Addition of the alcohol 42 to a solution of BF3 Et20/TMSCN in DCM provided the nitrile 43 in 83% yield. Hydrolysis of nitrile 43 then furnished amide 44 in 85% yield. Demethylation of the methoxyindole 44 with BBra in DCM provided the hydroxyindole 45 in 80% yield. This was followed by alkylation of 45 with the bromide 46 under phase transfer conditions to provide the phosphonate ester 47 and subsequent cleavage of the methyl ester by TMS-I furnished trimethylsilyl phosphonic acid 48, which upon alcoholic workup afforded LY311727. 

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