- Rhodium-catalyzed diarylation of oxalates using arylboron compounds
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Dialkyl oxalates undergo selective diarylation on one of their carbonyl carbons upon treatment with arylboron reagents in the presence of a rhodium catalyst to give the corresponding α-hydroxydiarylacetates. Under similar conditions, the arylation of benzoylformate and benzil also proceeds efficiently.
- Miyamura, Sawako,Satoh, Tetsuya,Miura, Masahiro
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- Dications of fluorenylidenes. The effect of substituent electronegativity and position on the antiaromaticity of substituted tetrabenzo[5.5]fulvalene dications
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Oxidation of 3,6-disubstituted tetrabenzo[5.5]fulvalenes by SbF5 results in the formation of dications that behave like two antiaromatic fluorenyl cations connected by a single bond. Both fluorenyl systems exhibit the paratropic shifts and nucleus independent chemical shifts (NICS) characteristic of antiaromatic species. Comparison with analogous 2,7-disubstituted tetrabenzo[5.5]fulvalenes reveals that the antiaromaticity of the substituted ring system can be altered substantially by changes in the placement of the substituents, possibly due to changes in the delocalization of charge in the system. Substituents in the 3,6-position decrease the antiaromaticity because of the increase in the benzylic resonance compared to 2,7-substituents.
- Levy, Amalia,Rakowitz, Amber,Mills, Nancy S.
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p. 3990 - 3998
(2007/10/03)
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