PubMed · 16257358
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Franklin E Mirer. 2005. Comment on Caprolactam study.. https://doi.org/10.1016/j.annepidem.2005.04.012
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The benzeneselenol-catalyzed, tributyltin hydride-mediated addition of phenolic iodides to benzene gives the 3-(hydroxyaryl)-1,4-cyclohexadienes, predominantly. Under conditions of controlled osmoylation, these are converted to the racemic 1,2-syn-2,3-anti-3-(hydroxyaryl)-4-cyclohexene-1,2-diols, whereas exhaustive osmoylation gives the 3-(hydroxyaryl)-3,5-dideoxymucoinositols, whose stereochemistry is established by X-ray crystallography.
The 500 MHz NMR spectra of water-benzene solution near saturation at 303.15, 323.15, and 343.15 K indicate that there is a proton-proton exchange between the water and benzene molecules. In the solution water appears to be present as a dimer attached to the benzene pi cloud on one side of each of the two (initially degenerate) fundamental energy levels, as predicted by the Jahn-Teller effect. This view is reinforced by the fact that one of its hydrogen atoms hovers above one of the carbon atoms and the other three are spread upward around the C6 axis of the benzene molecule. It is also supported by the calculated NMR spectra. Both effects are responsible for the change in the NMR spectra of the water molecules from a single line into four AB signals.
Sandwich and T-shaped configurations of substituted benzene dimers were studied by second-order perturbation theory to determine how substituents tune pi-pi interactions. Remarkably, multiple substituents have an additive effect on the binding energy of sandwich dimers, except in some cases when substituents are aligned on top of each other. The energetics of substituted T-shaped configurations are more complex, but nevertheless a simple model that accounts for electrostatic and dispersion interactions (and direct contacts between substituents on one ring and hydrogen atoms on the other), provides a good match to the quantum mechanical results. These results provide insight into the manner by which substituents csan be utilized in supramolecular design.