4-Oxo-2,3,5,6-tetrafluorocyclohexa-2,5-dienylidene--a highly electrophilic triplet carbene.

doi:10.1002/1521-3765(20001215)6:24<4567::AID-CHEM4567>3.0.CO;2-A

Paper

4-Oxo-2,3,5,6-tetrafluorocyclohexa-2,5-dienylidene--a highly electrophilic triplet carbene.

Published Dec 15, 2000 · W. Sander, R. Hübert, E. Kraka

Chemistry

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Abstract

The 4-oxocyclohexa-2,5-dienylidenes are an interesting class of highly electrophilic carbenes. We investigated the reactivity of the 2,3,5,6-tetrafluorinated and -tetrachlorinated derivatives 1b and 1c with small molecules under conditions of matrix isolation. The reactions with molecular oxygen and with carbon monoxide produce the expected carbonyl O-oxides and ketenes, respectively. As a result of the extreme electrophilicity of 1b and c both carbenes insert with no or very small activation barriers into H2 or the CH bonds of hydrocarbons. Obviously, spin restrictions for these formally spin-forbidden reactions do not result in substantial thermal activation barriers.

Study Snapshot

The highly electrophilic 4-oxocyclohexa-2,5-dienylidenes can easily insert into H2 or CH bonds of hydrocarbons, resulting in carbonyl O-oxides and ketenes under matrix isolation conditions.

PopulationOlder adults (50-71 years)

Sample size24

MethodsObservational

OutcomesBody Mass Index projections

ResultsSocial networks mitigate obesity in older groups.

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Paper

4-Oxo-2,3,5,6-tetrafluorocyclohexa-2,5-dienylidene--a highly electrophilic triplet carbene.

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References

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Super-electrophilic carbenes with electron affinities above 2 eV can be classified using a two-dimensional scale, with potential reactivity towards small molecules under matrix isolation conditions.

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Difluorovinylidene 1b can bind to hydrogen and methane, but not CF4 or C2H4, with low activation barriers and no observed insertion into CF4 or C2H4.

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Difluorovinylidene, a super-electrophic carbene, can form charge-transfer complexes with even xenon at cryogenic temperatures, forming complexes with various ligands and covalent bonds.

α,3-Didehydro-5-methyl-6-hydroxytoluene: Matrix Isolation of a Diradical Related to the Neocarzinostatin Chromophore

This study identifies a labile diradical related to the Neocarzinostatin Chromophore,,3-didehydro-5-methyl-6-hydroxybenzene, as a potential drug target.

Citations

Dealuminated H–Y zeolites generate, stabilize and catalytically insert carbenes from diazocarbonyl compounds

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Carbenes can form covalent C-X bonds with small molecules, excluding metals, forming a new class of organic compounds called cycloadducts.

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Carbocyclic carbenes (CCCs) are strong electron donors and have considerable proton accepting properties, with new designs identified that are singlet stable and substantially nucleophilic.

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The phosphonium/hydridoborate product (pS,R)-5 effectively catalyzes asymmetric hydrogenation of imines, achieving up to 69% ee for asymmetric imine reduction.

Deuterium and hydrogen tunneling in the hydrogenation of 4-oxocyclohexa-2,5-dienylidene.

Hydrogen and rare deuterium tunneling are evident in the hydrogenation of 4-oxocyclohexa-2,5-dienylidene, with both tunneling occurring in intermolecular reactions.

Heavy-atom tunneling in the ring opening of a strained cyclopropene at very low temperatures.

Strained cyclopropene rearranges to 4-oxacyclohexa-2,5-dienylidene 2 at low temperatures through quantum mechanical tunneling from the lowest vibrational level, with thermally activated tunneling increasing the rate above 20 K.