Competing acyl transfer and intramolecular O ? N acyl group migration from an isolable O-acylisourea

Hegarty, A. F.; McCormack, Margaret T.; Brady, Kieran; Ferguson, George; Roberts, Patrick D.

doi:10.1039/p29800000867

Cited by 21 publications

(5 citation statements)

References 6 publications

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“…(1) Upon N -protonation, amides 1c (R = Cy), 1e (R = t -Bu), 2c (R = Cy), and 2e (R = t -Bu) undergo intramolecular N - to O -acyl migration, indicative of high capacity of these amides as acylating reagents (Scheme A) . For the model compound in this class, 1a , a barrier of 0.70 kcal/mol has been found.…”

supporting

confidence: 89%

“…The data demonstrate that amidic resonance in N -acyl-glutarimides practically disappears ( E R < 2.8 kcal/mol), , while, intriguingly, these amides favor O -protonation despite significant twist . We also show that in some cases these amides undergo intramolecular N - to O -acyl migration, indicative of high capacity as acylating reagents. We expect that the mechanistic details presented herein will facilitate the development of new and broadly general amide N–C(O) bond cross-coupling reactions.…”

mentioning

confidence: 99%

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N-Acyl-glutarimides: Resonance and Proton Affinities of Rotationally-Inverted Twisted Amides Relevant to N–C(O) Cross-Coupling

Szostak

2018

Org. Lett.

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Resonance energies and proton affinities of N-acyl-glutarimides, compared with related twisted acyclic amides of relevance to N-C(O) cross-coupling, are reported. The data demonstrate that amidic resonance in N-acyl-glutarimides practically disappears (E < 2.8 kcal/mol), while, intriguingly, these amides favor O-protonation despite significant twist. In some cases, N-acyl-glutarimides undergo intramolecular N- to O-acyl migration, indicative of high capacity as acylating reagents. The understanding provided for the high reactivity of N-acyl-glutarimides should facilitate the development of a broadly general N-C(O) amide activation platform.

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supporting

confidence: 89%

mentioning

confidence: 99%

N-Acyl-glutarimides: Resonance and Proton Affinities of Rotationally-Inverted Twisted Amides Relevant to N–C(O) Cross-Coupling

Szostak

2018

Org. Lett.

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“…However, the time scale is inconveniently slow (days), and significant quantities (roughly 30%) of two byproducts are produced. These byproducts comprise both Ac2 - and EDC-derived moieties and are presumably the isomeric N -acylureas formed by unproductive rearrangements of the expected O -acylisourea intermediate. ,,, A previous work had shown that a catalytic amount of pyridine minimizes the formation of these byproducts . For this work, most reactions were carried out in pyridine/pyridinium buffer, which both eliminated the byproducts and shortened the total reaction times to tens of minutes …”

Section: Resultsmentioning

confidence: 99%

Structure–Property Effects in the Generation of Transient Aqueous Benzoic Acid Anhydrides by Carbodiimide Fuels

et al. 2019

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“…These byproducts comprise both Ac2-and EDC-derived moieties and are presumably the isomeric N -acylureas formed by unproductive rearrangements of the expected O-acylisourea intermediate. 36,43,58,59 Previous work had shown that a catalytic amount of pyridine minimizes the formation of these byproducts. 26 For this work, most reactions were carried out in pyridine/pyridinium buffer, which both eliminated the byproducts and shortened the total reaction times to tens of minutes.…”

Section: Resultsmentioning

confidence: 99%

Structure–property Effects in the Generation of Transient Aqueous Benzoic Acid Anhydrides by Carbodiimide Fuels

Kariyawasam¹,

Kron²,

Jiang³

et al. 2019

Preprint

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<div>The design of dissipative systems, which operate out-of-equilibrium by consuming chemical fuels, is challenging. As yet, there are few examples of privileged fuel chemistries that can be broadly applied in abiotic systems in the same way that ATP hydrolysis is exploited throughout biochemistry. The key issue is that designing nonequilibrium systems is inherently about balancing the relative rates of coupled reactions. The use of carbodiimides as fuels to generate transient aqueous carboxylic anhydrides has recently been used in examples of new nonequilibrium materials and supramolecular assemblies. Here, we explore the kinetics of formation and decomposition of a series of benzoic anhydrides generated from the corresponding acids and EDC under typical conditions (EDC = <i>N</i>-(3-dimethylaminopropyl)-<i>N</i>′-ethylcarbodiimide hydrochloride). The reactions can be described by a simple mechanism that merges known behavior for the two processes independently. Structure–property effects in these systems are dominated by differences in anhydride decomposition rate. The kinetic parameters allow trends in concentration-dependent properties to be simulated, such as reaction lifetimes, peak anhydride concentrations, and yields. For key properties there are diminishing returns with the addition of increasing amounts of fuel. These results should provide useful guidelines for the design of functional systems making use of this chemistry. <br></div>

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Competing acyl transfer and intramolecular O ? N acyl group migration from an isolable O-acylisourea

Cited by 21 publications

References 6 publications

N-Acyl-glutarimides: Resonance and Proton Affinities of Rotationally-Inverted Twisted Amides Relevant to N–C(O) Cross-Coupling

N-Acyl-glutarimides: Resonance and Proton Affinities of Rotationally-Inverted Twisted Amides Relevant to N–C(O) Cross-Coupling

Structure–Property Effects in the Generation of Transient Aqueous Benzoic Acid Anhydrides by Carbodiimide Fuels

Structure–property Effects in the Generation of Transient Aqueous Benzoic Acid Anhydrides by Carbodiimide Fuels

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