Dependence of transition-state structure on nucleophile in the reaction of aryl oxide anions with aryl diphenylphosphate esters

Basaif, Salem A.; Waring, Mark A.; Williams, Andrew

doi:10.1039/p29910001653

Cited by 26 publications

(26 citation statements)

References 22 publications

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“…• C, small values of β (0.12) have been obtained [13]. Nonetheless, despite the difference in the β values, all these reactions have been reported to proceed by a concerted mechanism.…”

Section: Introductionmentioning

confidence: 91%

“…On the other hand, attack only on the P center was observed for the reactions of aryl dimethylphosphinothioate and 2-(2,4 -dinitrophenyl)-2-oxo-1,3,2-dioxaphosphinanes with different phenoxide ions and some O-α nucleophiles [3,[11][12][13]. It is known that when the nucleophilic substitution reactions occur at the P center, they can proceed by two main types of mechanism: the stepwise mechanism, involving a trigonal bipyramidal pentacoordinate intermediate, and the concerted mechanism, through a single pentacoordinate transition state [3].…”

Section: Introductionmentioning

confidence: 93%

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Nucleophilic substitution reactions of diethyl 4‐nitrophenyl phosphate triester: Kinetics and mechanism

Castro

Ugarte

Rojas

et al. 2011

Int J of Chemical Kinetics

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The reactions of diethyl 4-nitrophenyl phosphate (1) with a series of nucleophiles: phenoxides, secondary alicyclic (SA) amines, and pyridines are subjected to a kinetic study. Under excess of nucleophile, all the reactions obey pseudo-first-order kinetics and are first order in the nucleophile. The nucleophilic rate constants (k N ) obtained are pH independent for all the reactions studied. The Brønsted-type plot (log k N vs. pK a nucleophile) obtained for the phenolysis is linear with slope β = 0.21; no break was found at pK a 7.5, consistent with a concerted mechanism. The Brønsted-type plots for the SA aminolysis and pyridinolysis are linear with slopes β = 0.39 and 0.43, respectively, also suggesting concerted processes. The concerted mechanisms for the latter reactions are proposed on the basis of the lack of break in the Brønsted-type plots and the instability of the hypothetical pentacoordinate intermediates formed in these reactions. C 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: [708][709][710][711][712][713][714] 2011

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“…• C, small values of β (0.12) have been obtained [13]. Nonetheless, despite the difference in the β values, all these reactions have been reported to proceed by a concerted mechanism.…”

Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 93%

Nucleophilic substitution reactions of diethyl 4‐nitrophenyl phosphate triester: Kinetics and mechanism

Castro

Ugarte

Rojas

et al. 2011

Int J of Chemical Kinetics

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“…As discussed above, the data for phosphate monoesters indicate only small changes in transition-state structure with different nucleophile and leaving-group p K a values (33). In contrast, LFERs for triesters indicate changes in the nature of the transition state with different substituent p K a values (37, 38, 55). In both cases, the directions of the changes can be understood simply in terms of perturbations to the energy surface in a two-dimensional reaction coordinate diagram (37, 55).…”

Section: Transition States For Phosphoryl Transfermentioning

confidence: 97%

“…In contrast, LFERs for triesters indicate changes in the nature of the transition state with different substituent p K a values (37, 38, 55). In both cases, the directions of the changes can be understood simply in terms of perturbations to the energy surface in a two-dimensional reaction coordinate diagram (37, 55). Thus, the LFER data, although not complete, are consistently and robustly accounted for by the current and longstanding models described above.…”

Section: Transition States For Phosphoryl Transfermentioning

confidence: 97%

Biological Phosphoryl-Transfer Reactions: Understanding Mechanism and Catalysis

Lassila

Zalatan

Herschlag

2011

Annu. Rev. Biochem.

377

662

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Phosphoryl-transfer reactions are central to biology. These reactions also have some of the slowest nonenzymatic rates and thus require enormous rate accelerations from biological catalysts. Despite the central importance of phosphoryl transfer and the fascinating catalytic challenges it presents, substantial confusion persists about the properties of these reactions. This confusion exists despite decades of research on the chemical mechanisms underlying these reactions. Here we review phosphoryl-transfer reactions with the goal of providing the reader with the conceptual and experimental background to understand this body of work, to evaluate new results and proposals, and to apply this understanding to enzymes. We describe likely resolutions to some controversies, while emphasizing the limits of our current approaches and understanding. We apply this understanding to enzyme-catalyzed phosphoryl transfer and provide illustrative examples of how this mechanistic background can guide and deepen our understanding of enzymes and their mechanisms of action. Finally, we present important future challenges for this field.

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“…For example, β eq decreases from 1.87 for diethylphosphate transfer to 1.30 for diphenylphosphate transfer to 1.22 for diphenylphosphinate transfer 30. This would suggest that the transition states are more advanced than indicated above.…”

Section: Discussionmentioning

confidence: 88%

Mechanism and Transition State Structure of Aryl Methylphosphonate Esters Doubly Coordinated to a Dinuclear Cobalt(III) Center

et al. 2009

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Reactivities of five phosphonate esters each coordinated to a dinuclear Co(III) complex were investigated ([Co 2 (tacn) 2 (OH) 2 {O 2 P(Me)OAr}] 3+ ; tacn = 1,4,7-triazacyclononane; substituent = m-F, p-NO 2 (1a); p-NO 2 (1b); m-NO 2 (1c); p-Cl (1d); unsubstituted (1e)). Hydrolysis of the phosphonate esters in 1a to 1e is specific base catalysed and takes place by intramolecular oxide attack on the bridging phosphonate. These data define a Brønsted β lg of −1.12, considerably more negative than that of the hydrolysis of the uncomplexed phosphonates (−0.69). For 1b, the kinetic isotope effects in the leaving group are 18 k lg = 1.0228 and 15 k = 1.0014, at the non-bridging phosphoryl oxygens 18 k non-bridge = 0.9954, and at the nucleophilic oxygen 18 k nuc = 1.0105. The KIEs and the β lg data point to a transition state for the alkaline hydrolysis of 1b that is similar to that of a phosphate monoester complex with the same leaving group, rather than the isoelectronic diester complex. The data from these model systems parallel the observation that in protein phosphatase-1, which has an active site that resembles the structures of these complexes, the catalysed hydrolysis of aryl methylphosphonates and aryl phosphates are much more similar to one another than the uncomplexed hydrolysis reactions of the two substrates.

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Dependence of transition-state structure on nucleophile in the reaction of aryl oxide anions with aryl diphenylphosphate esters

Cited by 26 publications

References 22 publications

Nucleophilic substitution reactions of diethyl 4‐nitrophenyl phosphate triester: Kinetics and mechanism

Nucleophilic substitution reactions of diethyl 4‐nitrophenyl phosphate triester: Kinetics and mechanism

Biological Phosphoryl-Transfer Reactions: Understanding Mechanism and Catalysis

Mechanism and Transition State Structure of Aryl Methylphosphonate Esters Doubly Coordinated to a Dinuclear Cobalt(III) Center

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