Site of Nucleophilic Attack and Ring Opening of Five-Membered Heterocyclic 2,3-Diones:  A Density Functional Theory Study

Fabian, Walter M. F.

doi:10.1021/jo026142o

Cited by 10 publications

(6 citation statements)

References 73 publications

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“…The bond between C 2 and ring-oxygen in the transition state is increased to 1.61 Å as compared to 1.38 Å in the reactant state. Although other mechanisms for the ring-opening of 1 and 1a are possible through nucleophilic addition of water at the C 5 C 6 bond (1 to 1f to 1g) as shown in Supporting Information Figure S1 or at the C 2 position of the lactone carbonyl (1 to 1g), 10 our calculations indicate that these alternative routes have higher activation barriers (Figure 2b). Following ring-opening of 1a, the resultant β-keto acid (1b) undergoes proton transfer (ΔE a = 20 kJ/mol) to form a stable (i.e., an optimized local energy minimum on the potential energy surface) zwitterion intermediate (1c) in solution that can subsequently decarboxylate to produce 1,3-pentadiene-2,4diol (1d) with a calculated activation energy barrier of 30 kJ/ mol.…”

Section: ■ Results and Discussionmentioning

confidence: 75%

Mechanistic Insights into Ring-Opening and Decarboxylation of 2-Pyrones in Liquid Water and Tetrahydrofuran

et al. 2013

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Abstract2-Pyrones, such as triacetic acid lactone, are a promising class of biorenewable platform chemicals that provide access to an array of chemical products and intermediates. We illustrate through the combination of results from experimental studies and first-principle density functional theory calculations that key structural features dictate the mechanisms underlying ring-opening and decarboxylation of 2-pyrones, including the degree of ring saturation, the presence of C═C bonds at the C4═C5 or C5═C6 positions within the ring, as well as the presence of a β-keto group at the C4 position. Our results demonstrate that 2-pyrones undergo a range of reactions unique to their structure, such as retro-Diels-Alder reactions and nucleophilic addition of water. In addition, the reactivity of 2-pyrones and the final products formed is shown to depend on the solvent used and the acidity of the reaction environment. The mechanistic insights obtained here provide guidance for the selective conversion of 2-pyrones to targeted chemicals. ABSTRACT: 2-Pyrones, such as triacetic acid lactone, are a promising class of biorenewable platform chemicals that provide access to an array of chemical products and intermediates. We illustrate through the combination of results from experimental studies and first-principle density functional theory calculations that key structural features dictate the mechanisms underlying ringopening and decarboxylation of 2-pyrones, including the degree of ring saturation, the presence of CC bonds at the C 4 C 5 or C 5 C 6 positions within the ring, as well as the presence of a β-keto group at the C 4 position. Our results demonstrate that 2-pyrones undergo a range of reactions unique to their structure, such as retro-Diels−Alder reactions and nucleophilic addition of water. In addition, the reactivity of 2-pyrones and the final products formed is shown to depend on the solvent used and the acidity of the reaction environment. The mechanistic insights obtained here provide guidance for the selective conversion of 2-pyrones to targeted chemicals. Disciplines Chemistry | Environmental

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Section: ■ Results and Discussionmentioning

confidence: 75%

Mechanistic Insights into Ring-Opening and Decarboxylation of 2-Pyrones in Liquid Water and Tetrahydrofuran

et al. 2013

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“…The mechanism of nucleophilic addition of water to certain heterocyclic compounds was examined by Fabian using the PCM (H2O) /B3LYP/6-31G* level of theory (Scheme 6). 51 Water assisted and unassisted addition of a nucleophile (water) at different positions of pyrrole-2,3-diones, leading to different products, was considered. Energetically the most preferred pathway involved a stepwise 1,4-addition of water.…”

Section: Generation Of Enamines and Iminium Ion Intermediatesmentioning

confidence: 99%

Microsolvated transition state models for improved insight into chemical properties and reaction mechanisms

Sunoj

Anand

2012

Phys. Chem. Chem. Phys.

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Over the years, several methods have been developed to effectively represent the chemical behavior of solutes in solvents. The environmental effects arising due to solvation can generally be achieved either through inclusion of discrete solvent molecules or by inscribing into a cavity in a homogeneous and continuum dielectric medium. In both these approaches of computational origin, the perturbations on the solute induced by the surrounding solvent are at the focus of the problem. While the rigor and method of inclusion of solvent effects vary, such solvation models have found widespread applications, as evident from modern chemical literature. A hybrid method, commonly referred to as cluster-continuum model (CCM), brings together the key advantages of discrete and continuum models. In this perspective, we intend to highlight the latent potential of CCM toward obtaining accurate estimates on a number of properties as well as reactions of contemporary significance. The objective has generally been achieved by choosing illustrative examples from the literature, besides expending efforts to bring out the complementary advantages of CCM as compared to continuum or discrete solvation models. The majority of examples emanate from the prevalent applications of CCM to organic reactions, although a handful of interesting organometallic reactions have also been discussed. In addition, increasingly accurate computations of properties like pK(a) and solvation of ions obtained using the CCM protocol are also presented.

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“…* For all stationary points for the minimum energy reaction path (see Scheme 4), the ZPE corrected total energies of the structures, and the relative energies for standard conditions (1 atm and 298 К) are given. 10, 11 The total energy of com pound 5 (R = H) and a proton at an infinite distance from each other was taken as the reference point.…”

Section: Rearrangement In An Alkaline Mediummentioning

confidence: 99%

Studies on mechanisms of the rearrangement of thieno[3,2-e][1,2,4]triazolo[4,3-c]pyrimidines into thieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidines

et al. 2006

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ul. Zorge, 344090 Rostov on Don, Russian Federation Recyclization of thieno[3,2 e][1,2,4]triazolo [4,3 c]pyrimidines was studied experimen tally and theoretically by B3LYP/6 31G** calculations in the gas phase and in solution (EtOH). The experimentally observed characteristic features of the isomerization (the possibility of the Dimroth rearrangement occurring by the ANRORC mechanism and high energy barriers in acid catalyzed reactions) were confirmed by quantum chemical calculations. Substituents in the triazole ring were found to play the principal role in the rearrangement.

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Site of Nucleophilic Attack and Ring Opening of Five-Membered Heterocyclic 2,3-Diones: A Density Functional Theory Study

Cited by 10 publications

References 73 publications

Mechanistic Insights into Ring-Opening and Decarboxylation of 2-Pyrones in Liquid Water and Tetrahydrofuran

Mechanistic Insights into Ring-Opening and Decarboxylation of 2-Pyrones in Liquid Water and Tetrahydrofuran

Microsolvated transition state models for improved insight into chemical properties and reaction mechanisms

Studies on mechanisms of the rearrangement of thieno[3,2-e][1,2,4]triazolo[4,3-c]pyrimidines into thieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidines

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