- Selective Alkenylation and Hydroalkenylation of Enol Phosphates through Direct C-H Functionalization
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An efficient and selective Rh-catalyzed direct C-H functionalization reaction of enol phosphates was developed. The method is applicable to a variety of coupling partners, including activated alkenes, alkynes, and allenes, and leads to the formation of various valuable alkenylated and hydroalkenylated enol phosphates through the action of the phosphate directing group. The versatility and utility of the coupling products were demonstrated through further transformations into synthetically useful building blocks. P points the way: A direct C-H functionalization of enol phosphates was developed. The method is applicable to a variety of coupling partners, including activated alkenes, alkynes, and allenes, and it leads to the formation of alkenylated and hydroalkenylated enol phosphates through the action of the phosphate directing group. The utility of the coupling products are demonstrated by further transformations into synthetically useful building blocks.
- Hu, Xu-Hong,Yang, Xiao-Fei,Loh, Teck-Peng
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supporting information
p. 15535 - 15539
(2016/01/26)
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- Base-mediated tandem reaction of α-aryloxyacetophenones with phosphonates: Selective synthesis of enol phosphates
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A new, simple method for the synthesis of enol phosphates by base-mediated tandem reaction of α-aryloxyacetophenones with phosphonates is described. In the presence of Cs2CO3, a variety of -aryloxyacetophenones smoothly underwent the sequential O-P bond-forming/C-O bond cleavage/isomerization tandem reaction with phosphonates at room temperature, providing the corresponding enol phosphates in moderate to excellent yields. Georg Thieme Verlag Stuttgart · New York.
- Song, Ren-Jie,Liu, Yan-Yun,Wu, Ji-Cheng,Xie, Ye-Xiang,Deng, Guo-Bo,Yang, Xu-Heng,Liu, Yu,Li, Jin-Heng
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experimental part
p. 1119 - 1125
(2012/05/04)
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- Darzens reaction of acyl phosphonates with α-bromo ketones: Selective synthesis of cis- and trans-epoxyphosphonates
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(Chemical Equation Presented) Acyl phosphonates with α-halo ketones in the presence of bases at room temperature afford cis- and trans-epoxyphosphonates in good chemical yields and high selectivities using different bases. The diastereoselectivity of this reaction is easily controlled by changing the base. Changing the base from Cs2CO3 to DBU changed the diastereomeric ratio (transieis) from 3/2 to 9/1. Moreover, the treatment of the trans isomer with DBU showed a complete conversion to the corresponding cis isomer.
- Demir, Ayhan S.,Emrullahoglu, Mustafa,Pirkin, Eser,Akca, Nazmiye
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scheme or table
p. 8992 - 8997
(2009/04/06)
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- An efficient separation method for enol phosphate and corresponding β-ketophosphonate from their mixtures under aqueous conditions
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Separation of a mixture β-ketophosphonate 3 and their corresponding enol phosphate 4 is efficiently carried out in aqueous alkaline solutions. Enol phosphate 4 is first extracted with hexanes:dichloromethane (19:1). Acidification of the aqueous layer followed by extraction of the β-ketophosphonate 3 with dichloromethane completes the separation. Thus, when 1-bromo-2,4-pentadione la reacted with triethyl phosphite to give diethyl (2,4-dioxopentyl)phosphonate 3a (Arbuzov-product) and the corresponding enol phosphate 4a (Perkow-product), separation of the two compounds was carried out using this method.
- Moorhoff, Cornelis M.
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p. 2069 - 2086
(2007/10/03)
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- Radical and Ionic Reactions of (Benzoylmethyl)mercurials
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Photolysis of PhCOCH2HgCl or (PhCOCH2)2Hg yields benzoylmethyl radicals which can be trapped by anions such as Me2C=NO2-, RC(CO2Et)2-, RC(O-)=CH2 or by other electron-rich systems such as (RO)3P, N-methylpyrrole, enamines, or norbornene.Electron transfer from the adduct radicals to the mercurials yields PhCOCH2A from the anions A-, PhCOCH2P(O)(OR)2 from P(OR)3, and the phenacyl derivative from N-methylpyrrole or enamines.Easily oxidized anions such as PhCOCPh2- or PhC(CH3)=NO2- react with PhCOCH2* by electron transfer to yield the dimer derived from the anion.Addition of PhCOCH2* to norbornene yields a substituted 3-benzoylpropyl radical which cyclizes at the ortho position of the benzoyl group to give the α-tetralone derivative.
- Russell, Glen A.,Kulkarni, Shekhar V.,Khanna, Rajive K.
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p. 1080 - 1086
(2007/10/02)
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- Synthsis of Conjugated Dienol Phosphates
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Conjugated dienol phosphates substituted at either the 1 or 2 position can be prepared from α,β- or β,γ-unsaturated ketones by treatment with lithium tetramethylpiperidine and a dialkyl or diaryl chlorophosphate.Simple enol phosphates can also be synthesi
- Blotny, Grzegorz,Pollack, Ralph M.
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p. 109 - 111
(2007/10/02)
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- Mechanism of the Reaction of Trialkyl Phosphites with α-Halogenoacetophenones in Alcoholic Solvents
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Second-order rate constants and activation parameters have been determined for the reactions of trialkyl phosphites in alcoholic media with α-chloro- or α-bromo-acetophenones having various substituents in the benzene ring (3,4-Me2, 4-Me, H, 4-Cl, and 4-I).Linear Hammett plots are consistent with the involvement of a common first intermediate in the rate-determining stage, leading to the formation of vinyl phosphate, α-hydroxyphosphonate, and acetophenone.The results provide the first kinetic evidence in support of the initial formation of the previously suggested betaine as a common intermediate in alcoholic solution.Further reaction then involves rearrangement to give the vinyloxyphosphonium species (and hence the Perkow product) or protonation followed by dealkylation to give the α-hydroxyphosphonate.Evidence for the possible formation of dehalogenated ketone via solvolysis of the α-hydroxyphosphonium intermediate is also presented.
- Petnehazy, Imre,Keglevich, Gyoergy,Toeke, Laszlo,Hudson, Harry R.
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p. 127 - 132
(2007/10/02)
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- LE POUVOIR EXTRACTANT DES PHOSPHONATES β CARBONYLES VIS-A-VIS DU CUIVRE, DU COBALT ET DU NICKEL
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The copper-cobalt-nickel separation being an nowadays industrial problem, this work was aimed to correlate the structure of some β carbonyl phosphonate compounds with the extractibility of three corresponding cations (4).The generalised formula of these compounds is: (RO)2P(O)-CH2-C(O)-R' and the way to synthesise them depends upon the nature of R and R' (R is always a saturated hydrocarbon radical).The different samples are described in table I.Toluen has been chosen as the dilutant and the studied pH domain extends from the pH of first contact between phases to the pH of precipitation of the metal hydroxides.The following compounds exhibit a slight affinity for copper, cobalt and nickel: E1 : R' is the phenyl radical.E2, E3 : R' is the parafluorophenyl radical.E5 : R' is a saturated hydrocarbon radical.E9 : R' is a partially fluorine substituted aliphatic radical.The compounds are not interesting for solving the industrial problem with which we are concerned.On the contrary, the following compounds exhibit, in certain conditions (pH, concentration) an excellent affinity for one or another of the three metals, allowing sometimes a complete extraction : E4 (figure 1) : R' is the hydrogen atom.E6, E7, E8 (table II, figure 2 and table III) : R' is a completely fluorine substituted aliphatic radical, by way of example E6 extracts well nickel or cobalt and E7, E8 extract well copper.One can notice the formation of a third phase with E7 (R = -C2H5).The substitution of the ethyl group by the normal butyl (E8, R = -C4H9) increases the lipophilicity of the complex metal phosphonate and the compound E8 is able to realise the purification of diluted cobalt or nickel aqueous solutions towards copper.
- Sturz, G.,Clement, J. C.,Daniel, A.,Molinier, J.,Lenzi, M.
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p. 161 - 172
(2007/10/02)
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