- A facile and practical preparation ofP-chiral phosphine oxides
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A practical and cost-effective synthetic method ofP-chiral diarylalkyl, aryldialkyl, and triaryl phosphine oxides by using readily available chiral diphenyl-2-pyrrolidinemethanol as the auxiliary is developed. The long-standing racemization issue during s
- Xu, Ronghua,Gao, Zhenhua,Yu, Yiteng,Tang, Yehua,Tian, Duanshuai,Chen, Tian,Chen, Yibing,Xu, Guangqing,Shi, Enxue,Tang, Wenjun
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p. 3335 - 3338
(2021/04/07)
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- METHOD FOR PRODUCING ORGANOPHOSPHORUS COMPOUND
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PROBLEM TO BE SOLVED: To provide a method for producing an organophosphorus compound which has excellent energy efficiency without containing a halogenated alkyl or a by-product derived from a halogenated alkyl. SOLUTION: There is provided a method for producing an organophosphorus compound by reacting a trivalent organophosphorus compound represented by the following general formula (1) in the presence of a super strong acid and/or at least one acid catalyst containing a solid superstrong acid catalyst to generate a pentavalent organophosphorus compound represented by the following general formula. (where Z1 represents OR2 or R2; Z2 represents OR3 or R3; R1, R2 and R3 represent an alkyl group, an alkenyl group or the like; when R2 and R3 are an alkyl group or the like, R2 and R3 may be bonded to each other to form a cyclic structure; and R1 may be a hydrogen atom.) SELECTED DRAWING: None COPYRIGHT: (C)2020,JPOandINPIT
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Paragraph 0051; 0079
(2020/05/02)
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- Scalable Enantiomeric Separation of Dialkyl-Arylphosphine Oxides Based on Host–Guest Complexation with TADDOL-Derivatives, and their Recovery
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Several dialkyl-arylphosphine oxides were prepared, and the enantioseparation of the corresponding racemates was elaborated with host–guest complexation using TADDOL-derivatives. The crystallization conditions were optimized and two separate crystallization methods, one in organic solvent, and the other in water, were found to yield five examples of phosphine oxides with enantiomeric excess values higher than 94 %. A gram scale resolution was performed, and both enantiomers of the methyl-phenyl-propyl-phosphine oxide were separated with (R,R)- or (S,S)-spiro-TADDOL. The intermolecular interactions responsible for the enantiomeric recognition between the chiral host and guest molecules were investigated by single-crystal X-ray diffractional structural determinations. The similarities in the structural patterns of a few diastereomeric crystals were checked by powder X-ray diffraction, as well. Organic solvent nanofiltration (OSN) was used as a scalable technique for the decomposition of the corresponding phosphine oxide–spiro-TADDOL molecular complexes, and for the recovery of the phosphine oxide enantiomers and resolving agents.
- Bagi, Péter,Fogassy, Elemér,Herbay, Réka,Holczbauer, Tamás,Keglevich, Gy?rgy,Mátrav?lgyi, Béla,Madarász, János,Székely, Gy?rgy,Varga, Bence
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supporting information
(2020/03/23)
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- Water determines the products: An unexpected Br?nsted acid-catalyzed PO-R cleavage of P(iii) esters selectively producing P(O)-H and P(O)-R compounds
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Water is found able to determine the selectivity of Br?nsted acid-catalyzed C-O cleavage reactions of trialkyl phosphites: with water, the reaction quickly takes place at room temperature to afford quantitative yields of H-phosphonates; without water, the reaction selectively affords alkylphosphonates in high yields, providing a novel halide-free alternative to the famous Michaelis-Arbuzov reaction. This method is general as it can be readily extended to phosphonites and phosphinites and a large scale reaction with much lower loading of the catalyst, enabling a simple, efficient, and practical preparation of the corresponding organophosphorus compounds. Experimental findings in control reactions and substrate extension as well as preliminary theoretical calculation of the possible transition states all suggest that the monomolecular mechanism is preferred.
- Li, Chunya,Wang, Qi,Zhang, Jian-Qiu,Ye, Jingjing,Xie, Ju,Xu, Qing,Han, Li-Biao
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supporting information
p. 2916 - 2922
(2019/06/18)
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- Desymmetrization of Phosphinic Acids via Pd-Catalyzed Asymmetric Allylic Alkylation: Rapid Access to P-Chiral Phosphinates
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The synthesis of P-chiral compounds is challenging, especially since useful catalytic methods for preparing such molecules are scarce. Herein we disclose a desymmetrization that employs phosphinic acids as prochiral nucleophiles in a Pd-catalyzed asymmetr
- Trost, Barry M.,Spohr, Simon M.,Rolka, Alessa B.,Kalnmals, Christopher A.
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supporting information
p. 14098 - 14103
(2019/10/11)
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- Sulfinamide Phosphinates as Chiral Catalysts for the Enantioselective Organocatalytic Reduction of Imines
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A new type of chiral sulfinamide phosphinate catalysts with up to three stereogenic centers, readily accessible from commercially available starting materials, is reported. The naphthyl derivative SulPhos proved to be highly efficient in the organocatalyt
- Chelouan, Ahmed,Recio, Rocío,Borrego, Lorenzo G.,álvarez, Eleuterio,Khiar, Noureddine,Fernández, Inmaculada
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supporting information
p. 3258 - 3261
(2016/07/14)
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- Stereoselective Synthesis of P-Stereogenic N-Phosphinyl Compounds
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A number of P-stereogenic N-phosphinyl compounds were stereoselectively prepared in good yields by a straightforward approach, thanks to the diversified and, up until now, unexplored reactivity of (R)- and (S)-dicyclohexylidene-D-glucose methyl phenyl pho
- Chelouan, Ahmed,Recio, Roco,lvarez, Eleuterio,Khiar, Noureddine,Fernndez, Inmaculada
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supporting information
p. 255 - 259
(2016/02/14)
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- Formation of unexpected heterocyclic products from pyrolysis of thiocarbonyl stabilised phosphonium ylides
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Chiral phthalimido thioxo-stabilised phosphonium ylides, prepared starting from (S)-alanine and (S)-phenylalanine, undergo intramolecular Wittig reaction upon pyrolysis leading to the previously unknown pyrrolo[2,1-a]isoindol-5-one-2- thiones, rather than
- Aitken, R. Alan,Barker, Graeme,Cleghorn, Lee P.,Reid, Euan J.,Roberts, Sheryl S.
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p. 1135 - 1147
(2014/01/17)
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- Direct conversion of phosphonates to phosphine oxides: An improved synthetic route to phosphines including the first synthesis of methyl JohnPhos
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The synthesis of tertiary phosphine oxides from phosphonates was achieved reliably and in good to excellent yields using stoichiometric amounts of alkyl or aryl Grignard reagents and sodium trifluoromethanesulfonate (NaOTf). In the absence of the NaOTf additive, covalent coordination oligomers of magnesium and phosphorus species dominate the reaction, producing very low yields of phosphine oxide, but high conversions of the phosphonate starting material. Mechanistic studies revealed that a five-coordinate phosphorus species - not a phosphinate - is the reaction intermediate. A diverse array of phosphonates was converted to phosphine oxides using a variety of Grignard reagents for direct carbon-phosphorus functionalization. This new methodology especially simplifies the synthesis of dimethylphosphino (RPMe2)-type phosphines by using air-, water-, and silica-stable intermediates. To highlight this reaction, a new Buchwald-type ligand ([1,1′-biphenyl]-2-yldimethylphosphine, or methyl JohnPhos) and a classic bidentate phosphine, bis(diphenylphosphino)propane (dppp), were synthesized in excellent yields.
- Kendall, Alexander J.,Salazar, Chase A.,Martino, Patrick F.,Tyler, David R.
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supporting information
p. 6171 - 6178
(2015/02/19)
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- Simple unprecedented conversion of phosphine oxides and sulfides to phosphine boranes using sodium borohydride
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A variety of phosphine oxides and sulfides can be efficiently converted directly to the corresponding phosphine boranes using oxalyl chloride followed by sodium borohydride. Optically active P-stereogenic phosphine oxides can be converted stereospecifically to phosphine boranes with inversion of configuration by treatment with Meerwein's salt followed by sodium borohydride.
- Rajendran, Kamalraj V.,Gilheany, Declan G.
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supporting information; experimental part
p. 817 - 819
(2012/02/03)
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- Enantioselective preparation of P-chiral phosphine oxides
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A highly efficient chiral auxiliary-based strategy for the asymmetric synthesis of P-chiral phosphine oxides in >98:2 er has been developed. The methodology involves the highly stereoselective formation of P-chiral oxazolidinones that then undergo displacement with a variety of Grignard reagents to prepare the desired phosphine oxides.
- Adams, Harry,Collins, Rebecca C.,Jones, Simon,Warner, Christopher J. A.
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supporting information; experimental part
p. 6576 - 6579
(2012/01/15)
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- Diastereoselective alkynylation of chiral phosphinoylimines: preparation of optically active propargylamines
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Chiral phosphinoylimines were prepared from methylphenylphosphonamides and tested as new chiral and activated imines. The addition of aluminum acetylides was proved to be highly diastereoselective while lithium or magnesium acetylides gave poor results. T
- Benamer, Mounira,Turcaud, Serge,Royer, Jacques
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scheme or table
p. 645 - 648
(2010/04/23)
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- Synthesis of P-stereogenic phosphorus compounds. Asymmetric oxidation of phosphines under appel conditions
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Racemic phosphines are converted into enantioenriched phosphine oxides via a synthetically simple, but theoretically interesting, oxidation procedure in good enantiomeric excess (up to 80%) and excellent yields (>95%). These phosphine oxides can be oxidatively coupled to provide easy access to enantiopure DiPAMPO analogues. Particularly attractive aspects of this procedure are the operational simplicity and the low cost required to synthesize these high value compounds. Copyright
- Bergin, Enda,O'Connor, Cormac T.,Robinson, Shane B.,McGarrigle, Eoghan M.,O'Mahony, Colm P.,Gilheany, Declan G.
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p. 9566 - 9567
(2008/02/13)
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- Practical synthesis of chiral vinylphosphine oxides by direct nucleophilic substitution. Stereodivergent synthesis of aminophosphine ligands
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A practical synthesis of optically pure alkylphenylvinylphosphine oxides is described, utilizing a nucleophilic displacement at phosphorus to install the vinyl moiety. The products were used to prepare classes of P-stereogenic aminophosphine (PN) and aminohydroxyphosphine (PNO) ligands. Stereocontrol can be exerted at various stages of the synthesis, to provide specific combinations of chirality in the final product. The effect of the stereogenic phosphorus and match-mismatch of chiralities of PNO ligands were examined in the asymmetric ruthenium-catalyzed hydrogen transfer reduction of three aryl ketones.
- Oliana, Marco,King, Frank,Horton, Peter N.,Hursthouse,Hii, King Kuok
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p. 2472 - 2479
(2007/10/03)
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- Novel 2-Phosphabicyclo[2.2.2]oct-5-ene Derivatives and Their Use in Phosphinylations
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The [4 + 2] cycloaddition of the double-bond isomers (A and B) of dihydrophosphinine oxide 1 afforded novel phosphabicyclo[2.2.2]oct-5-ene derivates (2-4), formation of which was justified by PM3 semiempirical calculations. The compounds of dimer type (2-
- Keglevich, Gyoergy,Kovacs, Janos,Koertvelyesi, Cavaes,Parlagh, Gyula,Imre, Timea,Ludanyi, Krisztina,Hegedus, Laszlo,Hanusz, Miklos,Simon, Kalman,Marton, Andrea,Marosi, Gyoergy,Toke, Laszlo
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- Lewis acid catalyzed room-temperature Michaelis-Arbuzov rearrangement
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The taming of the shrew! For the first time, a broadly applicable efficient room-temperature Arbuzov rearrangement is described. This reaction is accomplished through an atom-economical Lewis acid catalyzed process (see scheme, TMSOTf=trimethylsilyl trifluoromethane-sulfonate). The method has been generalized to primary and activated secondary phosphites, phosphinites, and phosphonites.
- Renard, Pierre-Yves,Vayron, Philippe,Leclerc, Eric,Valleix, Alain,Mioskowski, Charles
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p. 2389 - 2392
(2007/10/03)
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- Synthesis and fragmentation of new 2-phosphabicyclo[2.2.2]octene 2-oxides
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The substitution pattern of the 2-phosphabicyclo[2.2.2]octene framework and the skeleton itself were varied to obtain new cycloadducts usable in phosphorylations and to study their ability to undergo fragmentation. Thus, an N-methyl and several P-trialkylphenyl derivatives (7 and 9, respectively) were synthesized, together with two diaza species (8) whose stereostructure was evaluated by single crystal X-ray analysis. Mechanistic studies on the UV light-mediated photolysis of the P-aryl phosphabicyclooctenes (9) in the presence of methanol supports the suggestion of a novel addition-elimination reaction path.
- Keglevich, Gyoergy,Szelke, Helga,Tamas, Annamaria,Harmat, Veronika,Ludanyi, Krisztina,Vasko, Agnes Gyoengyver,Toke, Laszlo
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p. 626 - 632
(2007/10/03)
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- Synthesis and use of 6-, 7-and 8-membered P-heterocycles
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The synthesis of new families of P-heterocycles by reductive modifications, ring enlargement and Diels-Alder cycloaddition is described.
- Keglevich, Gyoergy,Toeke, Laszlo,Steinhauser, Kinga,Novak, Tibor,Ludanyi, Krisztina
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p. 593 - 596
(2007/10/03)
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- Photolysis of the cycloadduct of a 1,2-dihydrophosphinine oxide with N-phenylmaleimide in the presence of protic species: New aspects on the mechanism of the fragmentation of a 2-phosphabicyclo[2.2.2]octene
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Phosphabicyclo[2.2.2]octene 2 is useful in the UV light mediated phosphorylation of protic species. Experiments suggest that the fragmentation takes place according to concurrent EA and AE mechanisms.
- Keglevich, Gyoergy,Steinhauser, Kinga,Ludanyi, Krisztina,Toke, Laslo
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- Phosphinamides catalysts containing a stereogenic phosphorus atom for the asymmetric reduction of ketones by borane
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The effect of the configuration of the phosphorus atom in phosphinamide reduction catalysts has been studied through the preparation and use of a series of catalysts containing stereogenic phosphorus atoms of known configuration. The conclusion of this work is that a stereogenic centre at phosphorus can improve the selectivity of reductions using this catalyst, but is not sufficient in itself to generate the higher levels of selectivity which have been achieved with related catalysts. The X-ray crystallographic Structure of a key compound is also featured.
- Burns, Barry,Gamble, Mark P.,Simm, Athene R. C.,Studley, John R.,Alcock, Nathaniel W.,Wills, Martin
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- An intramolecular Arbuzov rearrangement initiated by anodic oxidation
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Dialkyl phenylphosphonite PhP(OR)2 (R = Et, Me) undergoes an intramolecular Arbuzov rearrangement upon electrolysis at an anode in acetonitrile under an oxygen atmosphere to yield alkyl alkylphenylphosphinate PhRP(=O)(OR). The results here suggest that the rearrangement takes place through a radical-chain mechanism initiated by anodic oxidation of the phosphonite to the corresponding cation radical.
- Yasui, Shinro,Shioji, Kosei,Tsujimoto, Munekazu,Ohno, Atsuyoshi
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p. 1625 - 1628
(2007/10/03)
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- Process of preparation of phosphinamides, applications and new products
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Phosphinamides are prepared by the action of an organic halide on an oxazaphospholidine. Depending upon the configuration desired for the stereoisomer to be obtained, an oxazaphospholidine is utilized which has been derived from a (+) or (-) optically-active amino-alcohol. These phosphinamides are useful for the preparation of phosphinates, in particular optically-active phosphinates of known absolute configuration; for this, the phosphinamide is subjected to alcoholysis.
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- Asymmetric synthesis of phosphinates, phosphine oxides and phosphines by Michaelis Arbuzov rearrangement of chiral oxazaphospholidine
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A general approach to asymmetric synthesis of high optically active tertiary organophosphorus compounds is described.Oxazaphospholidine 3 reacts with alkyl halide to give regio and stereoselectively the corresponding phosphinamide 4.Methyl phenyl phosphin
- Juge, S.,Genet, J. P.
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p. 2783 - 2786
(2007/10/02)
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- N-(Alkylphenylphosphinoyl)hydroxylamines: Highly Selective Migration of the Phenyl Group in the Base-induced Rearrangement of their O-Methylsulphonyl Derivatives
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The N-(alkylphenylphosphinoyl)hydroxylamines RPh(O)NHOH (R=Me, Et, or Pri) have been prepared and converted into their O-methylsulphonyl derivatives RPhP(O)NHOMs.These readily rearrange on treatment with methylamine, t-butylamine, or sodium methoxide-methanol to give only the products RP(O)(NHPh)X (X=NHMe, NHBut, or OMe) resulting from migration of the phenyl group.The rates of reaction are essentially the same when R=Me and R=Pri, indicating that the rearrangement is not brought about by nucleophilic attack at phosphorus.A likely mechanism involves base-induced rearrangement to a monomeric metaphosphonimidate which then reacts rapidly with the nucleophile.
- Harger, Martin J. P.,Smith, Adrian
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p. 683 - 688
(2007/10/02)
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- Alkoxyphosphonium ions. 5. Kinetics of the Michaelis-Arbuzov intermediate
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Rates of formation and destruction of the alkoxyphosphonium ion, the intermediate in the Michaelis-Arbuzov reactions of some methyl esters of trivalent phosphorus acids with methyl iodide, are followed by a conductivity method in the solvent propylene carbonate.Specific conductances of the unstable intermediates are well estimated through stable model salts.Rate constants for both the alkylation of the reagent and the dealkylation of the intermediate are obtained.The conductivity time curves are simulated by adjusting rate constants for two sequential second order reactions, assuming no ion pairing at the concentrations used.In these measurements of the intermediate only, there is no rate-determining step; for the overall rection the first step is in most cases rate-determining.
- Lewis, Edward S.,McCortney, Briget A.
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p. 1156 - 1160
(2007/10/02)
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- Kinetics and Mechanism of the Hydrolysis of Acyclic Oxyphosphonium Salts
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A kinetic study is reported of the hydrolysis of seven acyclic alkoxyphosphonium ions and two alkoxyaryloxyphosphonium ions .First-order rate constants follow the relationship kobsd=k0+kOH+kA, showing a reaction with water, hydroxide, and the base component of the buffer.The last two reactions are shown or argued to involve only P-O cleavage in the hydrolysis.The water reaction occurs with some C-O cleavage as well.The mixed phosphonium ions hydrolyze over a range of acidities to produce 4-methoxyphenol and the methyl phosphinate ester.The P-O cleavage reaction in all cases is argued to involve rate-limiting formation of a pentavalent hydroxyphosphorane intermediate.The buffer reaction represents general base catalysis of the addition of water, the base assisting the water attack by simultaneously removing a proton.Broensted coefficients are large, ranging from 0.6 to 0.85.This implies a transition state with a considerable amount of proton transfer.A comparison is presented with the general base-catalyzed hydration reactions of carbocations, which show significantly smaller β values.The water rates for the phosphonium ions lie close to the Broensted plots, suggesting that this reaction is also occuring with general base catalysis.Large rate decreases are observed with added acids and salts.These effects are explained by the general base mechanism with considerable hydronium ion character in the transition state.A comparison is also presented of the effects of sulfuric acid on the rates of hydrolysis of an alkoxyphosphonium ion and an analogous hydroxyphosphonium ion or protonated phosphinate ester.
- McClelland, Robert A.,McGall, Glenn H.,Patel, Geeta
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p. 5204 - 5209
(2007/10/02)
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- THE NATURE AND CONSEQUENCES OF THE INTERACTION OF PHOSPHORYL NUCLEOPHILES WITH A TRIORGANOSILYL CHLORIDE
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In order to throw light on the possible role of positively charged tetra-coordinate silicon intermediates in the racemization of α-NpPhMeSiCl (1) induced by uncharged nucleophiles two sets of kinetic studies have been carried out.In the first the rates of two reactions namely racemization of 1 catalysed by (PhO)2(Me3SiO)P=O (2) and transsilylation of 2 with 1, which take place together and are believed to involve the same intermediate were determined; the transsilylation was found to be faster than the racemization, and involved transient formation of an optically active product.In the second the racemization of 1 catalysed by HMPT in various CCl4/CH2Cl2 mixtures was studied; the rate was found to increase markedly with increase in the dielectric constant of the medium.The results of both sets of experiments were consistent with a mechanism involving a silyloxyphosphonium cation intermediate.
- Chojnowski, J.,Cypryk, M.,Michalski J.,Wozniak, L.
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p. 275 - 282
(2007/10/02)
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- Base-induced Rearrangement of the O-Methanesulphonyl Derivatives of N-(Alkylphenylphosphinoyl)hydroxylamines. Highly Selective Migration of the Phenyl Group
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The N-(alkylphenylphosphinoyl)-O-methanesulphonylhydroxylamines RPhP(O)NHOSO2Me (R = Me, Et, or Pri) react readily with MeNH2 or NaOMe-MeOH to give products resulting from phenyl, but not alkyl, migration.
- Harger, Martin J. P.,Smith, Adrian
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p. 1140 - 1141
(2007/10/02)
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- Alkoxyphosphonium Salts. 4. Kinetics and Mechanisms of Arbuzov Reactions
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The kinetics of the Arbuzov reactions of trivalent phosphorus esters of the type ABPOCH3 catalyzed by CH3X have been studied.The alkoxyphosphonium ion ABCH3POCH3+ is always intermediate but often undetected.In all cases studied using methyl iodide, the rate-determining step is the alkylation of the trivalent phosphorus and the intermediate alkoxyphosphonium ion does not accumulate detectibly by NMR.In all cases with methyl triflate, the alkylation is fast and complete, and the resulting alkoxyphosphonium salt then has a constant concentration.It methylates the triv alent compound (if any remains) in a measurably slow reaction, the only observed process.This reaction represents the pure "autocatalytic" mechanism.With dimethyl sulfate the intermediate accumulates but does not ordinarily persist, and the reaction course is best fit by a combination of the "autocatalytic" mechanism with attack on the intermediate phosphonium ion by ABPOCH3 and the "textbook" mechanism in which the intermediate alkoxyphosphonium ion is dealkylated by attack of the methyl sulfate anion.
- Lewis, Edward S.,Hamp, Donald
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p. 2025 - 2029
(2007/10/02)
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- PHOSPHORORGANISCHE VERBINDUNGEN 103. Die ozonolytische Desulfurierung von Thiophosphorylverbindungen: P=S -> P=O
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The sulfur atom in thiophosphorylgroups P=S is exchanged by oxygen with retention of configuration according to (1) and (2) as a result of an interaction of the P=S groups with ozone (Table 1 and 2).In dithiophosphinicacidesters only the thionosulfur is easily replaced by oxygen using ozone.The absolute configuration of the enantiomeric methyl-phenyl-phosphinicacid-p-nitrophenylesters 7 an 8 is controlled on the basis of the reaction circle (4).Serine enzymes are blocked by the phosphinicacidesters 7 and 8 by a rate factor of about 60 faster than by the corresponding thionophosphinicacidesters 5 and 6.The phosphinicacidesters 7 (and 8) have a high O-selectivity in competing reactions (7:n-BuOH:n-BuNH2 = 1:1:1) in contrast to the thionophosphinicacidesters 5 (and 6) with no selectivity (ester:amide = 4:6).
- Horner, L.,Flemming, H. W.
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p. 245 - 252
(2007/10/02)
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- PHOTOLYSIS OF SOME UNSYMMETRICAL PHOSPHINIC AZIDES IN METHANOL. RELATIVE MIGRATORY APTITUDES OF ALKYL GROUPS AND PHENYL IN THE CURTIUS-LIKE REARRANGEMENT.
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When an alkylphenylphosphinic azide RPhP(O)N3 (R=Me, Et, Pri or But) is photolysed in MeOH either the alkyl or phenyl group can migrate from P to N in the Curtius-like rearrangement.The composition of the product shows that migration of the alkyl group R is preferred.However, the preference is not great and decreases as R changes But->Pri->Et->Me-> (approx. migratory aptitudes relative to Ph: 2.1, 1.7, 1.3, 1.2 respectively), probably because the Ph-P bond is better able to assume the correct conformation for Ph migration when R is less bulky.For t-butylmethylphosphinic azide there is very little preference for migration of But relative to Me.Small amounts of unrearranged products such as ButPhP(O)NHOMe and ButPhP(O)NH2 are generally produced in the photolyses, together with the methyl phosphinates RPhP(O)OMe (major product when R=Me) resulting from (non-photochemical) solvolysis of the azide.
- Harger, Martin J. P.,Westlake, Sally
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p. 3073 - 3078
(2007/10/02)
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- GRIGNARD REACTION OF 2-PHENYL-TETRAHYDROPYRROLO-1,3,2-OXAZAPHOSPHOLES, OBSERVATION OF THE STEREOSPECIFIC INVERSION OF CONFIGURATION
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Grignard reaction of bicyclic oxazaphospholes proceeded with inversion of configuration to provide chiral phosphinic esters of known absolute configurations.
- Koizumi, Toru,Yanada, Reiko (nee Ishizaka),Takagi, Hiroyasu,Hirai, Hajime,Yoshii, Eiichi
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p. 571 - 572
(2007/10/02)
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- 1,3,2-Thiazaphospholidin-2-ones Derived From Ephedrine. Preparation and Stereochemistry of Ring-opening Reactions
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1,3,2-thiazaphospholidin-2-ones are prepared by rearrangement of the corresponding 1,3,2-oxazaphospholidine-2-thiones.In both the phosphono- and phosphoro-series treatment with alkoxide results in P-N bond cleavage with inversion of configuration, while treatment with Grignard reagents results in P-S bond cleavage with retention of configuration.The products are consistent with a mechanism which involves initial nucleophilic attack opposite endocyclic nitrogen.
- Hall, C. Richard,Williams, Nancy E.
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p. 2746 - 2750
(2007/10/02)
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- THE PREPARATION AND SOME REACTIONS OF 1,3,2-THIAZAPHOSPHOLIDINE-2-ONES
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1,3,2-Thiazaphospholidine-2-ones have been prepared by rearrangement of the corresponding 1,3,2-phospholidine-2-thiones.The stereochemical course of ring opening reactions has been investigated.
- Hall, Richard C.,Williams, Nancy E.
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p. 4959 - 4962
(2007/10/02)
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- PHOSPHINYLALKANOYL PROLINES
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New phosphinylalkanoyl prolines which have the general formula STR1 wherein R 1 is lower alkyl, phenyl or phenyl-lower alkyl; R 2 is hydrogen, phenyl-lower alkyl or a metal ion; R 3 is hydrogen or lower alkyl;R. sub. 4 is hydrogen, lower alkyl, phenyl-lower alkyl or a metal ion; andN IS 0 OR 1,ARE USEFUL AS HYPOTENSIVE AGENTS.
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- L-Dopa process and intermediates
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A process for the preparation of 3-(3,4-dihydroxyphenyl)-L-alanine (L-DOPA) wherein α-acetamido-4-hydroxy-3-alkoxy-cinnamic acid acetate is subjected to catalytic asymmetric hydrogenation to yield an optically active mixture N-acetyl-3-(4-hydroxy-3-alkoxyphenyl)-alanine acetate, with the L enantiomorph being present in a major amount and the D enantiomorph being present in a minor amount, from which N-acetyl-3-(4-hydroxy-3-alkoxyphenyl)-L-alanine acetate can be easily recovered and is then converted to L-DOPA. Novel precursors for L-DOPA are prepared in the process of this invention.
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