Allylic compounds phosphates

Wylation under neutral conditions. Reactions which proceed under neutral conditions are highly desirable, Allylation with allylic acetates and phosphates is carried out under basic conditions. Almost no reaction of these allylic Compounds takes place in the absence of bases. The useful allylation under neutral conditions is possible with some allylic compounds. Among them, allylic carbonates 218 are the most reactive and their reactions proceed under neutral conditions[13,14,134], In the mechanism shown, the oxidative addition of the allyl carbonates 218 is followed by decarboxylation as an irreversible process to afford the 7r-allylpalladium alkoxide 219. and the generated alkoxide is sufficiently basic to pick up a proton from active methylene compounds, yielding 220. This in situ formation of the alkoxide. which is a... 

The versatile Ti(II) chemistry available using preformed (alkene)Ti(OiPr)2 species was opened up by the discovery of the Kulinkovich cyclopropanation reaction [55]. Since 1995, Sato and collaborators have developed a wide range of elegant and synthetically useful reactions based on the Ti(OiPr)4/iPrMgCl reagent [56]. In particular, it was reported that the Ti(II) complex (q2-propene)Ti(OiPr)2, preformed from Ti(OiPr)4 and 2 equivalents of iPrMgCl, reacts with allylic compounds, such as halide, acetate, carbonate, phosphate, sulfonate, and aryl ether derivatives, to afford allyltitanium compounds as depicted in Scheme 13.27 [57]. 

For precautions, see Triallyl phosphate See Other ALLYL COMPOUNDS, SULFUR ESTERS... 

Allylic phosphates are more reactive than allylic acetates. Chemoselective reaction of the allylic phosphate moiety of the bis-allylic compound 88 with one equivalent of malonate, without attacking the allylic acetate moiety, takes place to give 89. Then the aminated product 90 was obtained by the addition of amine [52],... 

In scientific and patent literature on diene polymerization the following Nd(III)-salts are most often cited as catalyst precursors halides, carboxylates, alcoholates, phosphates, phosphonates, allyl compounds, cyclopentadienyl derivatives, amides, boranes and acetylacetonates. The catalyst systems based on these Nd-sources are reviewed in the following subsections. 

Nickel catalysts also catalyze Grignard substitution to allylic compounds including allyl alcohol [230-233] ethers [230,231,234,235 Eq. (106) 231] amines, albeit in a low product yield [231] sulfides [231,236,237], including thioacetals [238] thiols [231] selenides [239] carboxylates [240] phosphates [94,121] and halides [Eq. (107) 230], most likely via intermediate / -allyl-Ni species. Monosubstitution of bis-allyl ether was possible [Eq. (108) 235]. Most of the literatures cited in the foregoing disclosed regiochemical outcome associated with these allylic substitutions. 

Other allylic compounds having C-0 bonds, such as allylic carboxylates, carbonates, phosphates, ethers, and alcohols, can also serve as a substrate in such oxidative addition reactions via the C-0 bond cleavage [1]. 

A wide variety of photochemical transformations have been reported in organo-phosphorus compounds. Racemlzation of 1-phosphaallene enantiomers has been observed on exposure to light.Allyl diphenyl phosphate (211) undergoes a type II... 

Allylic compounds containing other leaving groups are also reactive toward substitution. Thus alkoxycarbonylation of allylic phosphates is a method of homologation, on which an interesting /3-lactam synthesis is based. Using PhjSiOH as nucleophile in the displacement, 2,4-hexadiene-l,6-diols are synthesizedfrom buta-dienyloxiranes. Desilylation of the products is achieved with KF. 

As shown above many allylic compounds can be used for catalytic reactions with different reactivity. Allylic esters such as carbonates, acetates, and phosphates are widely used. Allylic acetates and phosphates react in the presence of bases such as EtsN and AcONa. However, Giambastiani and Poli reported that allylation of -keto esters, but not malonates, with allylic acetates can be carried out under neutral conditions, although the reaction is slower [5]. 

Their reactivities are different. Although allylation with allylic chlorides proceeds without a Pd catalyst, their reaction is accelerated in the presence of a Pd catalyst. Allylic alcohols are rather poor substrates. Instead, their esters, typically allylic acetates, are used for smooth allylation. Allylic phosphates are more reactive than allylic acetates, and the chemoselective reaction of the allylic phosphate moiety of the bis-allylic compound with 1 equiv of malonate without attacking the allylic acetate moiety occurs (Scheme 5). Then the aminated product is obtained by the addition of amine. In addition to allylic esters, even allylic nitro compounds i-Piand sulfonest Hio] aHyiatjoj, Reactions of... 

As described in many reviews, Trost and his co-workers have carried out a pioneering work on the molybdenum-and tungsten-catalyzed allylic alkylation of allylic esters regioselectivity of the reaction is often complementary to the palladium-catalyzed allylic alkylation. The first asymmetric version was disclosed by Pfaltz and Lloyd-Jones in 1995 (Equation (63)). They used a catalytic amount of a novel tungsten complex, prepared from [W(CO)3(MeCN)3] or [W(cycloheptatriene) (COIs] and optically active (diphenylphosphino)phenyloxazolines 57, for the allylic alkylation of 3-aryl-2-propenyl phosphate with dimethyl sodiomalonate to isolate the corresponding branched alkylated compounds as a major isomer with an excellent enantioselectivity (96% ee). Unexpectedly, 3-aryl-2-propenyl carbonates are shown to be unreactive. It is worth noting that an isostructural molybdenum complex does not promote the catalytic alkylation under the same reaction conditions. In contrast, Lloyd-Jones and Lehmann reported the stereocontrolled... 

An alternate approach has been developed by Charette and coworkers in which chiral iodomethylzinc phosphates were prepared and tested in the cyclopropanation of unfunctionalized alkenes. Although these reagents were not sufficiently reactive to convert aryl-substituted alkenes (such as indene) to the corresponding cyclopropane, they reacted nicely with protected aryl-substituted allylic and homoallylic alcohols (equation 92) °. Several 3,3 -disubstituted binols were tested and ligand 23 stood out as being the most effective with this class of compounds. The active reagent in this case is a chiral iodomethylzinc phosphate. 

BuySnAl(CjHs)2 (12, 339-341). Reaction of allylic phosphates with this reagent (1) and a Pd(0) catalyst affords allyltin compounds, which react with aldehydes to produce homoallylic alcohols in 65-85% yield. The reaction involves predominant inversion of stereochemistry.1... 

Similar to the formation of allylmagnesium chloride (25), the oxidative addition of allyl halides to transition metal complexes generates allylmetal complexes 26. However, in the latter case, a 7i-bond is formed by the donation of 7i-electrons of the double bond, and resonance of the n-allvl and 7i-allyl bonds in 26 generates the 7i-allyl complex 27 or (/ -allyl complex. The carbon-carbon bond in the 7i-allyl complexes has the same distance as that in benzene. Allyl Grignard reagent 25 is prepared by the reaction of allyl halide with Mg metal. However, the 7i-allyl complexes of transition metals are prepared by the oxidative addition of not only allylic halides, but also esters of allylic alcohols (carboxylates, carbonates, phosphates), allyl aryl ethers and allyl nitro compounds. Typically, the 7i-allylpalladium complex 28 is formed by the oxidative addition of allyl acetate to Pd(0) complex. 

Triallylphosphate is the phosphate triester of allyl alcohol and contains unsaturated C=C bonds in its structure. This compound is a liquid (fp, -50°C). It is regarded as having a high toxicity and produces abnormal tissue growth when administered subcutaneously. It has been known to explode during distillation. 

Neurotoxic chemicals and motor neuropathy Chlorpyrifos, dichlorvos (DDVP), EPN, n-hexane, 2-hexanone, lead, lead chromate, lead II thiocyanate, leptophos, methamidophos, mipafox, omethoate, parathion, trichlor-fon, trichloronate, triorthocresyl phosphate Neurotoxic chemicals and sensorimotor neuropathy acrylamide, allyl chloride, arsenic and compounds, arsenic trichloride, calcium arsenate, carbon disulfide, dichloroacetylene, ethylene oxide, gallium arsenide, lead arsenate, mercuric chloride, mercuric nitrate, mercurous nitrate, mercury, nitrous oxide, phenyl arsine oxide, thallium and soluble compounds, thallous nitrate... 

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