Emerging computational approaches for the study of regio- and stereoselectivity in organic synthesis

Nakliang, Pratanphorn; Yoon, Sanghee; Choi, Sun

doi:10.1039/d1qo00531f

Cited by 13 publications

(9 citation statements)

References 99 publications

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“…In our opinion, the use of an approximate model that is capable of simulating, in a simple manner, an ideal case in which the interaction between biological macromolecules is optimal does not represent a limitation. In fact, theoretical models based on mathematical approximations are commonly employed in other fields of chemistry, such as investigation of reaction mechanisms [ 64 , 65 , 66 ] or simulation of spectroscopy experiments [ 67 ].…”

Section: Resultsmentioning

confidence: 99%

An Origami Paper-Based Biosensor for Allergen Detection by Chemiluminescence Immunoassay on Magnetic Microbeads

et al. 2022

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Food allergies are adverse health effects that arise from specific immune responses, occurring upon exposure to given foods, even if present in traces. Egg allergy is one of the most common food allergies, mainly caused by egg white proteins, with ovalbumin being the most abundant. As allergens can also be present in foodstuff due to unintended contamination, there is a need for analytical tools that are able to rapidly detect allergens in food products at the point-of-use. Herein, we report an origami paper-based device for detecting ovalbumin in food samples, based on a competitive immunoassay with chemiluminescence detection. In this biosensor, magnetic microbeads have been employed for easy and efficient immobilization of ovalbumin on paper. Immobilized ovalbumin competes with the ovalbumin present in the sample for a limited amount of enzyme-labelled anti-ovalbumin antibody. By exploiting the origami approach, a multistep analytical procedure could be performed using reagents preloaded on paper layers, thus providing a ready-to-use immunosensing platform. The assay provided a limit of detection (LOD) of about 1 ng mL−1 for ovalbumin and, when tested on ovalbumin-spiked food matrices (chocolate chip cookies), demonstrated good assay specificity and accuracy, as compared with a commercial immunoassay kit.

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Section: Resultsmentioning

confidence: 99%

An Origami Paper-Based Biosensor for Allergen Detection by Chemiluminescence Immunoassay on Magnetic Microbeads

et al. 2022

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“…Using the Gibbs free energy difference of the found TSs, we have calculated [42] the regioisomer ratio χ calc and compared it with the experimentally determined ratio χ exp (Table 4):

χ_{calc} = \frac{k_{1}}{k_{2}} = e^{- \frac{△ △ G^{\neq}}{R T}},

where k 1 and k 2 —rate constants of competing reactions, ΔΔG —the difference of relative Gibbs free energies of TSs of competing reactions, R —ideal gas constant, T —reaction temperature.…”

Section: Quantum Chemical Calculationsmentioning

confidence: 99%

“…The first one, so called MEDT, introduced by Domingo [27,40], actively uses conceptual DFT tools [41] as well as it is based on the analysis of electron density distribution in isolated reactants and on the dynamics of its change during the course of the reaction. The second one is pure thermodynamic approach dealing with the energy profiles of competing reactions [42]. The last approach is able to take into account the effect of steric hindrances at reaction centers, as well as entropy factor.…”

Section: Quantum Chemical Calculationsmentioning

confidence: 99%

[3 + 2] Cycloaddition of nitrile oxides to dichloropropenes and 1,3‐dichlorobut‐2‐ene: A regioselectivity issue

Shilova,

Shatokhina,

Kondrashov

2024

Journal of Heterocyclic Chem

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The reaction of nitrile oxides with 2,3‐dichloroprop‐1‐ene, 1,3‐dichloroprop‐1‐ene, and 1,3‐dichlorobut‐2‐ene leads to 5‐(chloromethyl)isoxazoles, 4‐(chloromethyl)isoxazoles, or to mixtures of both regioisomers. The direction of cycloaddition and reactivity of substrate is determined by the steric hindrance at the terminal carbon atom of the alkene double bond. It has been found that the isomeric products of cycloaddition of nitrile oxides to 1,3‐dichloropropene have significantly different dehydrochlorination capabilities. The experimental data on the regioselectivity of cycloaddition and the relative reactivity of substrates are in agreement with the results of quantum chemical calculations.

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“…Although the mechanistic model in Scheme represents a striking example of intramolecularly cooperative bimetallic catalysis for the copolymerization of meso -epoxides and cyclic anhydrides, many questions remain unanswered in terms of the high activity and enantioselectivity commonly observed in such systems. Thus, we herein report our investigation into the effects of multichiral ligands on the reactivity and enantioselectivity of the epoxide ring-opening step during the biaryl-linked bimetallic aluminum complex-mediated copolymerization of cyclohexene oxide (CHO) and phthalic anhydride (PA). ,− For this purpose, we employ a combination of experimental and computational methods. − Several key aspects of this catalytic system are examined, namely, the manner of epoxide coordination to the aluminum ion, the optimal route for ring-opening of the epoxide and the anhydride, the stereoselectivity of the epoxide ring-opening step, the difference in chiral induction for the bimetallic and monometallic paths, and the effect of the ortho -substituents of the phenolate ligand (Scheme ).…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Basis for the High Enantioselectivity and Activity in the Multichiral Bimetallic Complex-Mediated Enantioselective Copolymerization of meso-Epoxides

et al. 2022

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The desymmetric ring-opening copolymerization of meso-epoxides with cyclic anhydrides or carbon dioxide (CO2) constitutes a straightforward route to diverse isotactic polymers with two contiguous stereogenic centers. Both high enantioselectivity and excellent activity have been observed in catalyst systems based on biaryl-linked bimetallic complexes with multiple chiralities. In this study, we analyzed the basis for the high enantioselectivity and activity of multichiral bimetallic catalysts by combining experimental observations and theoretical calculations. More specifically, density functional theory calculations of the entire catalytic cycles for the copolymerization of cyclohexene oxide (CHO) and phthalic anhydride (PA) or CO2 demonstrated that ligand exchange was required for CHO coordination, while the ring-opening stage was the rate-determining step. Notably, the M···M separation and the endo dihedral angle of the bimetallic complex changed continuously during copolymer propagation, wherein the cleft opened and closed alternately, demonstrating that a flexible phenol–phenol (biphenol) axis is essential. The carboxylate anion coordinated simultaneously with both metal ions in the dinuclear catalyst reduces the reaction energy barrier during the ligand exchange process significantly. Calculation of the optimal routes for the coordination of CHO to Al(III) or Co(III) ions indicated three possible states. The energy barriers for CHO ring-opening mediated by the (R,R,R a ,R,R)- and (R,R,S a ,R,R)-isomers were calculated in each state, and it was found that epoxide ring-opening was sensitive to the absolute stereochemistries of the biphenol linker and the cyclohexyl diamine skeletons, as well as the phenolate ortho-substituents. The two diastereoisomers have opposite stereoselectivities in the epoxide ring-opening stage, wherein the (R,R,R a ,R,R)-isomer-mediated CHO ring-opening process at the (S)-C–O bond in the most stable CHO coordination state exhibited the lowest energy barrier, therefore determining the enantiomer preference and the copolymerization rate.

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Emerging computational approaches for the study of regio- and stereoselectivity in organic synthesis

Abstract: Computational chemistry has become important in organic synthesis as it provides a detailed understanding of molecular structures and properties and detailed reaction mechanisms.

Cited by 13 publications

References 99 publications

An Origami Paper-Based Biosensor for Allergen Detection by Chemiluminescence Immunoassay on Magnetic Microbeads

An Origami Paper-Based Biosensor for Allergen Detection by Chemiluminescence Immunoassay on Magnetic Microbeads

[3 + 2] Cycloaddition of nitrile oxides to dichloropropenes and 1,3‐dichlorobut‐2‐ene: A regioselectivity issue

Mechanistic Basis for the High Enantioselectivity and Activity in the Multichiral Bimetallic Complex-Mediated Enantioselective Copolymerization of meso-Epoxides

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