Posts Tagged ‘Solutions’
Thursday, May 2nd, 2019
Ken Houk’s group has recently published this study of cycloaddition reactions, using a combination of classical transition state location followed by molecular dynamics trajectory calculations,[1] and to which Steve Bachrach’s blog alerted me. The reaction struck me as being quite polar (with cyano groups) and so I took a look at the article to see what both the original[2] experimental conditions were and how the new simulations compared. The reaction itself is shown below.
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References
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X. Xue, C.S. Jamieson, M. Garcia-Borràs, X. Dong, Z. Yang, and K.N. Houk, "Ambimodal Trispericyclic Transition State and Dynamic Control of Periselectivity", Journal of the American Chemical Society, vol. 141, pp. 1217-1221, 2019. http://dx.doi.org/10.1021/jacs.8b12674
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C.Y. Liu, and S.T. Ding, "Cycloadditions of electron-deficient 8,8-disubstituted heptafulvenes to electron-rich 6,6-disubstituted fulvenes", The Journal of Organic Chemistry, vol. 57, pp. 4539-4544, 1992. http://dx.doi.org/10.1021/jo00042a039
Tags:Chemistry, computational chemistry, Implicit solvation, Ken Houk, Molecular dynamics, Molecular modelling, Natural sciences, Physical sciences, Solutions, Solvent, Solvent model, Solvents, Steve Bachrach, Theoretical chemistry
Posted in reaction mechanism | 2 Comments »
Thursday, January 7th, 2016
This is the third and final study deriving from my Ph.D.[1]. The first two topics dealt with the mechanism of heteroaromatic electrophilic attack using either a diazonium cation or a proton as electrophile, followed by either proton abstraction or carbon dioxide loss from the resulting Wheland intermediate. This final study inverts this sequence by starting with the proton abstraction from an indolinone by a base to create/aromatize to a indole-2-enolate intermediate, which only then is followed by electrophilic attack (by iodine). Here I explore what light quantum chemical modelling might cast on the mechanism.
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References
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B.C. Challis, and H.S. Rzepa, "Heteroaromatic hydrogen exchange reactions. Part VIII. The ionisation of 1,3-dimethylindolin-2-one", Journal of the Chemical Society, Perkin Transactions 2, pp. 1822, 1975. http://dx.doi.org/10.1039/P29750001822
Tags:Arenium ion, Bases, diazo, Diazonium compound, Electrophile, Electrophilic aromatic substitution, Equilibrium chemistry, Fortran, Historical, Indole, light quantum chemical modelling, Metal ions in aqueous solution, Nuclear physics, Simple aromatic rings, Solutions
Posted in reaction mechanism | No Comments »