- A biomimetic synthesis of thiazolines using hexaphenyloxodiphosphonium trifluoromethanesulfonate
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Most chemical syntheses of thiazolines use serine residues, whereas nature employs cysteine residues. In a biomimetic approach, [(Ph3P+)2O](OTf-)2 was used to promote triphenylmethyl (Tr) deprotection
- You, Shu-Li,Razavi, Hossein,Kelly, Jeffery W.
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- The structure of polymer-supported triphenylphosphine ditriflate: A potentially useful reagent in organic synthesis
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(Chemical Equation Presented) The structure of a polymer-supported version of the Hendrickson "POP" reagent, prepared by the reaction of polymer-supported triphenylphosphine oxide 1 with triflic anhydride, is established as an equilibrium mixture of polym
- Petersson, Maria J.,Jenkins, Ian D.,Loughlin, Wendy A.
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- Air- and water-stable Lewis acids: Synthesis and reactivity of P-trifluoromethyl electrophilic phosphonium cations
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A new class of electrophilic phosphonium cations (EPCs) containing a -CF3 group attached to the phosphorus(v) center is readily accessible in high yields, via a scalable process. These species are stable to air, water, alcohol and strong Br?nsted acid, even at raised temperatures. Thus, P-CF3 EPCs are more robust than previously reported EPCs containing P-X moieties (X = F, Cl, OR), and despite their reduced Lewis acidity they function as Lewis acid catalysts without requiring anhydrous reaction conditions.
- Fasano,LaFortune,Bayne,Ingleson,Stephan
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supporting information
p. 662 - 665
(2018/02/06)
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- Synthesis of substituted phenols via hydroxylation of arenes using hydrogen peroxide in the presence of hexaphenyloxodiphosphonium triflate
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A mild and efficient protocol for the synthesis of phenols from arenes has been developed using aqueous hydrogen peroxide as an oxidizing agent and hexaphenyloxodiphosphonium triflate as a promoter. The reactions were carried out with the simple procedure in EtOH-H2O at room temperature in short reaction times.
- Khodaei, Mohammad Mehdi,Alizadeh, Abdolhamid,Hezarkhani, Hadis Afshar
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p. 878 - 882
(2018/11/06)
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- Hendrickson reagent induced rearrangement of aryl propargyl alcohols to α,β-unsaturated aldehydes
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The Hendrickson reagent (triphenylphosphonium anhydride trifluoromethanesulfonate), prepared from the reaction of triphenylphosphine oxide (Ph3PO) and triflic anhydride (Tf2O) (2:1 stoichiometry), promotes dehydrations and various coupling reactions. The reagent has been used to transform oximes to nitriles and to prepare esters, amides and many other functional groups through the intermediacy of an alkoxyphosphonium salt. The reagent proved useful in heterocycle synthesis of thiazolines, imidazolines, quinoline precursors, isoquinolines, β-carbolines, phenanthridines, 11H-indolo[3,2-c]quinolines, quinoline-lactones, furoquinolinones, and indolizino[1,2-b]quinolin-9(11H)-ones. Moreover, the reagent has been key to the successful total synthesis of several natural products. Aryl propargyl alcohols with a terminal α-acetylenic group undergo rapid conversion to the corresponding α,β-unsaturated aldehydes at room temperature in dichloromethane in the presence of one equivalent of triphenylphosphonium anhydride trifluoromethanesulfonate. The reaction involved adding freshly distilled Tf2O (1.0 mmol) to a solution of Ph3PO (2.0 mmol) in CH2Cl2 (10 mL) at 0oC under N2 atmosphere. After stirring for 10 min, the propargyl alcohol (1.0 mmol) was added as a CH2Cl2 solution (2 mL), followed by the addition of water and Et3N (2.0 mmol) and further stirring at room temperature for 1h. Subsequent workup with 5% NaHCO3 (20 mL) and purification afforded α,β-unsaturated aldehydes. Eighteen aryl propargyl alcohol substrates with a terminal α-acetylenic group were transformed in good to excellent yields (71-85%) to enals. The methodology proved successful with secondary and tertiary alcohols with stereoselectivity favouring exclusively the E isomer. All the synthesized compounds are known and were characterized (1H,13C, and M.P) and compared to literature values. The method offers several advantages such as exclusive stereoselectivity, short reaction time, good yield, mild reaction conditions, and simple operational procedure.
- Moussa, Ziad,Aljuhani, Ateyatallah
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p. 845 - 853
(2018/11/06)
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- Carbodiphosphorane mediated synthesis of a triflyloxyphosphonium dication and its reactivity towards nucleophiles
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A carbodiphosphorane ((Ph3P)2C) mediated synthesis of the first triflyloxyphosphonium dication (12+) bearing two electrophilic sites is presented. Depending on the nucleophile, 12+ reacts selectively either at the sulfur atom of the triflyloxy moiety or at the directly attached phosphorus atom. In substitution reactions at the phosphorus atom the triflyloxy moiety serves as a leaving group and enables the synthesis of rare examples of pseudo-halophosphonium dications.
- Yogendra,Hennersdorf,Bauzá,Frontera,Fischer,Weigand
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p. 2954 - 2957
(2017/03/15)
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- Cyclodehydration of N -(aminoalkyl)benzamides under mild conditions with a hendrickson reagent analogue
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Methods for the cyclodehydration of N-(aminoalkyl)benzamides are few and employ harsh reaction conditions. We have found that the easily prepared phosphonium anhydrides 1 (Hendrickson reagent) or 2 can be used for cyclodehydration of N-(aminoalkyl)benzamides under very mild conditions (room temperature) to produce five-, six-, and seven-membered cyclic amidines. Good yields are obtained by employing a temporary trityl group protection strategy. Cyclic analogue 2 can be used when the product cyclic amidine is organic-soluble, thus producing water-soluble byproducts.
- Loughlin, Wendy A.,Jenkins, Ian D.,Petersson, Maria J.
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p. 7356 - 7361
(2013/08/23)
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- Dehydrative glycosylation with the Hendrickson reagent
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The Hendrickson reagent is able to perform efficiently dehydrative glycosylation of 1-hydroxyglycosyl donors. The reaction occurs under mild conditions through an anomeric oxophosphonium intermediate detected by nuclear magnetic resonance. Further insight into the mechanism was gained by 18O labeling of anomeric OH.
- Mossotti, Matteo,Panza, Luigi
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experimental part
p. 9122 - 9126
(2011/12/16)
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- A versatile protocol for the quantitative and smooth conversion of phosphane oxides into synthetically useful pyrazolylphosphonium salts
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A convenient protocol for the smooth conversion of the resistant P-O bond in phosphane oxides into a reactive P-N bond of synthetically useful pyrazolylphosphonium salts is described. A highly charged, oxophilic, phosphorus-centered trication is employed and the reactions are conducted at room temperature with quantitative yields. The resulting pyrazolylphosphonium cations are valuable synthetic intermediates and are used for the synthesis of a variety of organophosphorus compounds. This represents a new approach towards the transformation of the rather inert phosphoryl group under very mild reaction and workup conditions and aims towards alternatives to existing reduction methods for phosphane oxide functionalization.
- Feldmann, Kai-Oliver,Schulz, Stephen,Klotter, Felix,Weigand, Jan J.
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p. 1805 - 1812
(2012/04/04)
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- Development of diphenylamine-linked bis(imidazoline) ligands and their application in asymmetric Friedel-Crafts alkylation of indole derivatives with nitroalkenes
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The new diphenylamine-linked bis(imidazoline) ligands were prepared through Kelly-You's imidazoline formation procedure mediated by Hendrickson 's reagent in good yields. The novel ligands were tested in the asymmetric Friedel-Crafts alkylation of indole derivatives with nitroalkenes. In most cases, good yields (up to 97%) and excellent enantioselectivities (up to 98%) can be achieved. The optimized bis(imidazoline) ligand with trans-diphenyl substitution on the imidazoline ring gave better enantioselectivity than the corresponding bis(oxazoline) ligand.
- Liu, Han,Du, Da-Ming
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experimental part
p. 1113 - 1118
(2010/07/03)
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- NMR Studies and electrophilic properties of triphenylphosphine-trifluoromethanesulfonic anhydride; a remarkable dehydrating reagent system for the conversion of aldoximes into nitriles
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NMR Studies on the reaction of triphenylphosphine with various amounts of triflic anhydride at 0 °C is described. The reagent structure resulting from mixing 1.3 equiv of Ph3P with Tf2O (1.0 mmol) has been established as an equilibrium mixture consisting mainly of triphenyl(trifluoromethylsulfonyloxy)phosphonium trifluoromethanesulfinate and the corresponding bis(triphenyl)oxodiphosphonium trifluoromethanesulfinate dimer. The electrophilic properties of the system have been exploited in the development of a mild method for converting aldoximes into nitriles. The dehydration occurs at 0 °C under very mild conditions by initial activation of the oxime oxygen, followed by treatment with a base and subsequent elimination of triphenylphosphine oxide. The substrate scope and functional group tolerance of this useful method are explored.
- Moussa, Ziad,Ahmed, Saleh A.,ElDouhaibi, Ahmad S.,Al-Raqa, Shaya Y.
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scheme or table
p. 1826 - 1831
(2010/09/07)
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- The use of phosphonium anhydrides for the synthesis of 2-oxazolines, 2-thiazolines and 2-dihydrooxazine under mild conditions
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β-Hydroxy amides 6 and 7 were treated with triphenylphosphonium anhydride trifluoromethane sulfonate (3), or the cyclic analogue 4, to generate 2-oxazolines 5 and 8 under mild conditions. The reaction was optimised by examining the number of equivalents of reagents 3 or 4, or diisopropylethyl amine required to best effect cyclisation. The effects of altering the reaction temperature, reaction time, concentration, solvent, and addition rate also were investigated. However, it was found that use of a trityl group to block reaction at the hydroxyl or thiol group of the starting amides, and subsequent in situ detritylation, in the absence of base, led to greatly improved yields. Reagent 4 offered significant advantages in the purification of products and was used to dehydrate a range of trityl derivatives to form simple oxazolines, thiazolines, and a dihydro-1,3-oxazine, in high yield (85-99%), as well as a tetrahydro-1,3-oxazepine (31%).
- Petersson, Maria J.,Jenkins, Ian D.,Loughlin, Wendy A.
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body text
p. 739 - 746
(2009/06/20)
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- Access to functionalized quinones via the aromatic oxidation of phenols bearing an alcohol or olefinic function catalyzed by supported iron phthalocyanine
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The controlled oxidation at only one position of compounds with several oxidizable sites, while keeping the other sites intact, has been demonstrated for phenols bearing alcohol or olefinic functional groups. Iron tetrasulfophthalocyanine supported on silica was found to be an efficient catalyst for the preparation of functionalized quinones under mild conditions, with tert-butylhydroperoxide as the oxidant. A novel rapid and mild one-pot procedure for the covalent grafting of iron tetrasulfophthalocyanine onto silica has been developed. The supported catalyst was characterized by chemical analysis, a specific surface study, UV-vis spectroscopy and XPS. A non-radical mechanism for this unusual selective oxidation has been revealed by 18O labelling experiments. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
- Zalomaeva, Olga V.,Sorokin, Alexander B.
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p. 1768 - 1773
(2008/02/05)
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- Highly efficient 4-O-alkylations of tetronic acids involving oxyphosphonium intermediates
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4-Alkoxy-5H-furan-2-ones were prepared in fair to high yields by regioselective 4-O-alkylation of tetronic acids with stoichiometric amounts of primary and secondary alcohols. This approach involves the intermediacy of (5-oxo-2,5-dihydrofuran-3-yloxy) phosphonium trifluoromethanesulfonates, which were generated in situ on reaction of tetronic acids with triphenylphosphonium anhydride trifluoromethanesulfonate (Hendrickson's reagent).
- Paintner, Franz F.,Allmendinger, Lars,Bauschke, Gerd
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- A new synthesis of azetidin-2-ones
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Diphosphonium trifluoromethanesulfonate Ph3P+-O-P+Ph3.2SO3CF3- readily brings about direct annelation of imines to substituted azetidin-2- ones.
- Bari,Sethi,Sharma, Ashok K.
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p. 1121 - 1122
(2007/10/03)
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- Reactions of Carboxylic Acids with "Phosphonium Anhydrides"
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General considerations are outlined for a reagent to extract oxygen from organic molecules by an equivalent of dehydration.Reagents, (R3P+)2O, 2OTf-, were created for the purpose and subjected to a preliminary study.They were found to convert carboxylic acids readily and rapidly to anhydrides, esters, amides, amidines, benzimidazoles, and cyclic aryl ketones in good yields.
- Hendrickson, James B.,Hussoin, Md. Sajjat
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p. 1144 - 1149
(2007/10/02)
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