Experimental and DFT study of the conversion of ephedrine derivatives into oxazolidinones. Double SN2 mechanism against SN1 mechanism

Moncef, Abdelkarim El; Hadrami, El Mestafa El; González, Miguel A.; Zaballos-García, Elena; Zaragozá, Ramón J.

doi:10.1016/j.tet.2010.04.097

Cited by 8 publications

(4 citation statements)

References 63 publications

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“…A similar situation was observed by Tantillo and Nguyen, who reported the kinetic instability of tertiary carbocations owing to the presence of three alkyl groups. The failure to locate carbocations and the corresponding transition structures has also been reported for nucleophilic substitutions . As indicated above, in our particular case, the presence of a phenyl ring can help to stabilize the carbocation.…”

Section: Resultssupporting

confidence: 75%

Pivotal Neighboring‐Group Participation in Substitution versus Elimination Reactions – Computational Evidence for Ion Pairs in the Thionation of Alcohols with Lawesson's Reagent

et al. 2017

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The mechanism of the thionation of alcohols with Lawesson's reagent was explored through quantum chemical DFT methods. Evidence that carbocations are involved was found. The mechanism is completely different to that established recently for the thionation of carbonyls. The presence of a phenyl ring at the alcoholic carbon atom exerts a pivotal role in the stability of the carbocation and enables a S–π interaction, which is crucial for favoring thionation instead of undesired elimination. The influence of the solvent was also studied, and elimination is preferred in toluene, whereas substitution leading to thionation is favored in acetonitrile. A clear correlation between solvent polarity and elimination was observed. The study is in complete agreement with the different behavior observed experimentally for primary, secondary, and tertiary alcohols (bearing a phenyl ring or not), and the best conditions for minimizing undesired elimination can be predicted.

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Section: Resultssupporting

confidence: 75%

Pivotal Neighboring‐Group Participation in Substitution versus Elimination Reactions – Computational Evidence for Ion Pairs in the Thionation of Alcohols with Lawesson's Reagent

et al. 2017

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“…The advent of advanced and accessible methods of computational molecular modelling in recent decades has provided chemists with an indispensable tool for calculating theoretical properties, enabling researchers to validate experimental findings through cross-referencing with sophisticated independent calculations. Quantum density-functional theory (DFT) methods have been extensively demonstrated to provide reliable theoretical information on studied systems, such as mechanistic pathways 14 of reactions, transition states 15 and electronic configurations, as well as predictions of empirically observable properties, such as molecular structure 16 , nuclear magnetic resonance shifts 17 and bond vibrational frequencies 18 . The extended and constant refinement of computational methods has led to the creation of a dizzying variety of available parameters for use in DFT calculations, comprising of different exchange-correlation (XC) functionals, as well as functional rungs of theory, basis sets, including basis set enhancements such as polarisation and diffuse orbitals, solvation models and even the inclusion of dispersion and range-separation terms 19 .…”

Section: Introductionmentioning

confidence: 99%

IR of Vanillin: A classic study with a twist

Nicolaou,

Senn,

Gibson

et al. 2023

Preprint

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In this research, we delve into the vibrational spectroscopy of vanillin, a widely used aromatic and flavouring agent, through a comprehensive computational analysis. We employ a variety of common computational chemistry functionals and basis sets to calculate the infrared (IR) and Raman spectra of vanillin, aiming to shed light on its structural and spectroscopic properties. Our investigation entails benchmarking these theoretical results against one another to identify the most accurate computational approach. Furthermore, we compared our theoretical findings with experimental IR and Raman spectra to evaluate the degree of agreement between theory and experiment. This comparative analysis provides insights into the reliability of the chosen computational methods in capturing the vibrational behaviour of vanillin, a crucial aspect for applications in the food and pharmaceutical industries. In future work we plan to expand this study to other compounds aiming to bridge the gap between theory and experiment, this study contributes to a deeper understanding of vanillin's molecular behaviour, ultimately enhancing our knowledge of its sensory and chemical attributes.

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“…Since many reactions which proceed with retention of configuration involve a double inversion, 27 the cyclic chloronium ion 16b has been presented as a likely intermediate (Scheme 2). Cyclic chloronium ions have previously been postulated, to explain counterintuitive stereoselectivity in ring opening reactions of ω-chloroepoxides.…”

Section: Resultsmentioning

confidence: 99%

Reactions of enantiopure cyclic diols with sulfuryl chloride

et al. 2014

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Monocyclic allylic cis-1,2-diols reacted with sulfuryl chloride at 0 °C in a regio- and stereo-selective manner to give 2-chloro-1-sulfochloridates, which were hydrolysed to yield the corresponding trans-1,2-chlorohydrins. At -78 °C, with very slow addition of sulfuryl chloride, cyclic sulfates were formed in good yields, proved to be very reactive with nucleophiles and rapidly decomposed on attempted storage. Reaction of a cyclic sulfate with sodium azide yielded a trans-azidohydrin without evidence of allylic rearrangement occurring. An enantiopure bicyclic cis-1,2-diol reacted with sulfuryl chloride to give, exclusively, a trans-1,2-dichloride enantiomer with retention of configuration at the benzylic centre and inversion at the non-benzylic centre; a mechanism is presented to rationalise the observation.

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Experimental and DFT study of the conversion of ephedrine derivatives into oxazolidinones. Double SN2 mechanism against SN1 mechanism

Cited by 8 publications

References 63 publications

Pivotal Neighboring‐Group Participation in Substitution versus Elimination Reactions – Computational Evidence for Ion Pairs in the Thionation of Alcohols with Lawesson's Reagent

Pivotal Neighboring‐Group Participation in Substitution versus Elimination Reactions – Computational Evidence for Ion Pairs in the Thionation of Alcohols with Lawesson's Reagent

IR of Vanillin: A classic study with a twist

Reactions of enantiopure cyclic diols with sulfuryl chloride

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