Vinyls aryl phosphates

Aryl Phosphates. Aryl phosphates were introduced into commercial use early in the twentieth century for flammable plastics such as cellulose nitrate and later for cellulose acetate. CeUulosics are a significant area of use but are exceeded now by plastici2ed vinyls (93—95). Principal appHcations are in wire and cable insulation, coimectors, automotive interiors, vinyl moisture barriers, plastic greenhouses (Japan), furniture upholstery, conveyer belts (especially in mining), and vinyl foams. 

In vinyls, the aryl phosphates are frequently used in combinations with phthalate plastici2ers. The proportion of the more expensive phosphate is usually chosen so as to permit the product to reflably pass the flammability specifications. In plastici2ed vinyls used in automotive interiors, these phosphates are used to pass the Federal Motor Vehicle Safety Standard 302. 

Moy, P, Aryl phosphate ester fire-retardant additive for low-smoke vinyl applications, J. Vinyl Addit. Tech., 2004, 10(4), 187-192. 

The cleavage of carbon-oxygen bonds from alkenyl or aryl phosphates can be accomplished under reductive conditions with a low valent metal. As vinyl phosphates can be formed readily from ketones, this procedure provides a method to convert a ketone to an alkene. For example, the alkenyl phosphate 74 was prepared by trapping the enolate formed on reduction of the enone 73 and was converted into the alkene 75 (7.55). The chemistry therefore provides a method to prepare structurally specihc alkenes. Low-valent titanium (prepared for example by reduction of titanium(III) chloride with potassium metal) is a convenient alternative to lithium or sodium in liquid ammonia or an amine for the reductive cleavage of alkenyl or aryl phosphates. 

Allylic phosphates have become especially attractive and popular electrophilic coupling partners toward nonracemically ligated copper species capable of delivering their covalently bound residues in an enantiocontrolled Sn2 sense. Remarkably, the technologies have advanced to the state where carbon sp (alkyl), sp (vinyl, aryl), and even sp (alkynyl) residues on boron are all transferrable via copper in the desired fashion, and where both yields and ee s (or dr s), for the most part, are impressive. 

For preparative purposes, titanium metal can be used in place of sodium or lithium in liquid ammonia for both the vinyl phosphate and aryl phosphate" cleavages. The titanium metal is generated in situ from TiCla by reduction with potassium metal in tetrahydrofuran. 

Addition to linear 1,1-disubstituted allylic acetates is slower than addition to monosubstituted allylic esters. Additions to allylic trifluoroacetates or phosphates are faster than additions to allylic carbonates or acetates, and reactions of branched allylic esters are faster than additions to linear allylic esters. Aryl-, vinyl, alkynyl, and alkyl-substituted allylic esters readily undergo allylic substitution. Amines and stabilized enolates both react with these electrophiles in the presence of the catalyst generated from an iridium precursor and triphenylphosphite. 

Palladium/silver-catalyzed Heck reactions have usually involved vinyl or aryl halides and alkenes, but these reaction conditions were also extended to allenes. Indeed, Zenner and Larock65 showed that simple alkyl allenes readily reacted with aryl and vinyl iodide derivatives in the presence of palladium acetate or chloride and silver phosphate. Moreover, the reaction could be rendered asymmetric using chiral ligands the best one was a bisoxazolidine derivative (Scheme 10.37). 

Phosphate esters (alkyl or aryl, or mixed) of phosphoric acid constitute an important family of organophosphorus flame retardants.25 Triethylphosphate, a colorless liquid boiling between 209°C and 218°C, and containing 17 wt % phosphorus, has been used commercially as an additive for polyester resins/laminates and in cellulosics. In polyester resins, it functions as a viscosity depressant as well as a flame retardant. Trioctylphosphate is employed as a speciality flame-retardant plasticizer for vinyl composites where low temperature flexibility is critical. It can be also included in blends, along with general purpose plasticizers, such as phthalate esters, to improve low temperature flexibility. 

NMR experiments on the reactions of halophosphates esters with pyridine showed that equilibria involving the formation of pyridinium salts in these reactions are almost entirely shifted to the left for chloro- and bromo-phosphates and to the right for the corresponding iodophosphates. This explains dramatic differences in chemical reactivity between these compounds. Substituted medium-sized and large N-heterocycles (117) have been prepared via an extension of the Suzuki reaction involving the palladium-catalysed coupling of vinyl-phosphates (118) with aryl or heteroaryl boronic acids (Scheme 27). ... 

Introduction of an alkyl, vinyl- or aryl moiety into the 1-position of a cyclopropylamine was realized by the reaction of l-(l-trimethylsiloxycyclopropyl)piperidine with Grignard reagents to give product 1. ° Addition of the silyl ether to a tetrahydrofuran solution of the Grignard reagent, followed by workup with 10% sodium dihydrogen phosphate solution gave the best results. 

The reaction of silylated fluoromethylphosphonate carbanions with a large variety of alkyl, vinyl, or aryl chloroformates or with carbon dioxide proceeds smoothly at low temperature to give silylated l-(alkoxycarbonyl)-l-fluoromethylphosphonates and 1-(hydroxycarbonyl)-1-fluoromethylphosphonate, respectively (Scheme 3.58). For the electron-withdrawing carboxyl group, the traces of base already present in the reaction medium are sufficient to effect a desilylation if EtOH is added to the mixture. The desilylated products are isolated in 80-91% yields." - " The addition of EtOLi leads to decomposition with loss of phosphate. 

Spirofused (3-lactams related to 64 were prepared from 3-hydroxy-3-arylpropanamides after activation of the hydroxyl group by formation of a phosphate ester <97JOC6412>. A similarly easy cyclization occurred when the A-aryl amide 66 was treated with potassium carbonate <97TA739>. Radical induced 4-e.w-trig cyclizations of yV-vinyl-2-bromobutan-... 

In the case of oxygen leaving groups, not only aryl and vinyl triflates [36], but also dienyl phosphates [108] and aryl sulfamates such as 175 [109] can be used efficiently (Scheme 5.38). 

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