Aminolysis of substituted phenyl quinoline-8- and -6-carboxylates with primary and secondary amines. Involvement of proton-slide catalysis

Bruice, Paula Yurkanis; Bruice, Thomas C.

doi:10.1021/ja00824a033

Cited by 16 publications

(14 citation statements)

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“…Molecular-modelling studies showed that amino-group activity in the receptors corresponded to a Bruice proton slide-like mechanism, in which the non-bonding electrons of the good H-bond acceptor (amino group) facilitate proton transfer. [32][33][34][35] Nevertheless, the basic amino group is also able to establish intramolecular H bonds with the xanthoneamide groups, reducing the substrate association constant. As a consequence, the measured half-life time of the reaction does not reflect the actual catalytic activity.…”

Section: Introductionmentioning

confidence: 99%

“…As a consequence, the measured half-life time of the reaction does not reflect the actual catalytic activity. As pointed out by Bruice [32,33] it is the ability as an H-bond acceptor and not the basicity that is important for an auxiliary group to carry out the proton transport in a proton-slide mechanism. Therefore, in this paper the catalytic effect of non-basic oxy- gen atoms, which are good H-bond acceptors, [36][37][38] is reported.…”

Section: Introductionmentioning

confidence: 99%

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Enzyme Mimics for Michael Additions with Novel Proton Transport Groups

et al. 2008

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Molecular receptors with an enzyme‐like behavior in the Michael addition of pyrrolidine to an α,β‐unsaturated lactam have been designed. Catalytic activities are discussed and related to the substrate association constants. Chiral assistance of enantiomerically pure receptors was also investigated. One of the receptors shows a 4:1 enantiomeric ratio (60 % ee) for the addition of pyrrolidine and 3‐pyrroline.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Enzyme Mimics for Michael Additions with Novel Proton Transport Groups

et al. 2008

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“…) toward knQ4aH cannot be neglected at p H 9-33. However, the contribution of kl [ NMPPZH'] [ SH] compared with other terms in equation(19) can still be negligible. At pH 9.33, the value of (k&a + kiKw + kiKz)ak of 7.13 x…”

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confidence: 99%

Kinetics and mechanism of the cleavage of phthalimide in buffers of tertiary and secondary amines. Evidence of intramolecular general acid–base catalysis in the reactions of phthalimide with secondary amines

Khan

Ohayagha

1991

J of Physical Organic Chem

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The reaction rates of the cleavage of phthalimide (PTH) were studied at 30°C in buffer solutions of trimethylamine, triethylamine, triethanolamine, carbonate, piperidine, dimethylamine, morpholine, piperazine and N‐methylpiperazine at different pH values. The reactivity of carbonate, triethylamine and triethanolamine toward PTH could not be detected under the experimental conditions applied. However, triethylamine revealed nucleophilic reactivity toward non‐ionized PTH (SH). The steric requirements of triethylamine and triethanolamine are ascribed to the absence of nucleophilic reactivities of these amines toward SH. Secondary amines show nucleophilic reactivity toward both SH and ionized PTH (S−). The absence of nucleophilic reactivity of trimethylamine and the presence of nucleophilic reactivity of secondary amines toward S− are attributed to the occurrence of intramolecular general acid‐base catalysis due to the presence of a mobile proton at the nucleophilic site of the nucleophile. Intermolecular general base catalysis was observed in the reactions of SH with all secondary amines except piperidine and such catalysis could be detected in the reactions of S− with morpholine, piperazine and N‐methylpiperazine. Nucleophilic second‐order rate constants for the reactions of secondary amines with SH (k1) and S− (k2) reveal the Brønsted plots of slopes of ca 0.8 and 0.3, respectively. Similarly, the general base‐catalysed third‐order rate constants (k4) for the reactions of secondary amines with SH yield a Brønsted plot of slope 1.2. These observations suggest the occurrence of diffusion‐controlled trapping stepwise and pre‐association stepwise mechanisms in the aminolysis of non‐ionized and ionized phthalimide, respectively.

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“…The estimated values of the rate constants for the nitrogen leaving group in (I) 2 1 and (11) l6 have been found to be lO9-lO'' and 3 x lo9 s-', respectively. On the basis of these results, the value of the rate constant k_22 (Scheme 2) could be assumed to be significantly larger than 109-10'0 s-l because the push provided by the groups attached to the reaction centre to expel the cationic nitrogen leaving group from T' would most likely be more in T' than in (I) or in (11). In Scheme 2, the rate constant k, represents the diffusional separation of > N and H2N: groups from an intramolecular encounter complex (TAH).…”

Section: "*'2 An Additional Kinetic Term K K [ M H ] [ B ] [ O H ] Wh...mentioning

confidence: 99%

Intramolecular general acid–base catalysis and the rate-determining steps in the nucleophilic cleavage of maleimide- with primary amines

Khan¹

1985

J. Chem. Soc., Perkin Trans. 2

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The kinetics of nucleophilic cleavage of maleimide have been studied at 30 "C under the buffer solutions of 13 primary amines including three diamines and carbonate. Both ionized ( S -) and non-ionized (SH) forms of maleimide have been found to exhibit significant reactivity toward amines and carbonate anion. The respective bimolecular rate constants k, and k, for the reactions of nucleophiles with non-ionized and ionized forms of maleimide display Bronsted plots with respective slopes of pnuc, = 0.81 f 0.1 5 and pnuc, = 0.48 f 0.19. The significantly different values of pnuc, and pnuc, reveal the involvement of different rate-determining steps in the nucleophilic cleavage of non-ionized and ionized maleimide. The high value of pnuc, is attributed to the expulsion of the leaving group as the rate-determining step while the value of pnuc, of 0.48 indicates the nucleophilic attack within the encounter complex as the ratedetermining step. The values of pnuc, and pnuc, for the nucleophilic reactivity of diamines were found to be 0.52 f 0.02 and 0.13 f 0.02, respectively. The value of pnuc, of 0.52 has been attributed to intramolecular general acid-base-catalysed expulsion of the leaving group as the rate-determining step. The l o w value of pnuc, (0.13) reveals the nucleophilic attack as the rate-determining step. A preassociation stepwise mechanism is proposed for the reactions of amines with Swhile a diffusioncontrolled trapping mechanism is favoured for the reactions of amines with SH. The rate constants k, and k, for TRIS, 2-amino-2-methylpropane-1,3-diol, ammonia, and carbonate have been found to show significant negative deviations while hydrazine revealed a large positive deviation from Bronsted plots.

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Aminolysis of substituted phenyl quinoline-8- and -6-carboxylates with primary and secondary amines. Involvement of proton-slide catalysis

Cited by 16 publications

References 2 publications

Enzyme Mimics for Michael Additions with Novel Proton Transport Groups

Enzyme Mimics for Michael Additions with Novel Proton Transport Groups

Kinetics and mechanism of the cleavage of phthalimide in buffers of tertiary and secondary amines. Evidence of intramolecular general acid–base catalysis in the reactions of phthalimide with secondary amines

Intramolecular general acid–base catalysis and the rate-determining steps in the nucleophilic cleavage of maleimide- with primary amines

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