The carbonyl−olefin metathesis reaction could facilitate rapid functional group interconversion and allow construction of complicated organic structures. Herein, we demonstrate that elemental iodine, a very simple catalyst, can efficiently promote this chemical transformation under mild reaction conditions. Our mechanistic studies revealed intriguing aspects of the activation mode via molecular iodine and the iodonium ion that could change the previously established perception of catalyst and substrate design for the carbonyl−olefin metathesis reaction.

The non-benzenoid aromatic tropylium ion acts as an efficient promoter for carbonyl–olefin metathesis reactions.

Substituted pyrans and furans are core structures found in a wide variety of natural products and biologically-active compounds. Herein, we report a practical and mild catalytic method for the synthesis of substituted pyrans and furans using molecular iodine, a simple and inexpensive catalyst. The method described herein is performed in solvent-free conditions in ambient temperature and atmosphere, thus offering a facile and green alternative to currently available reaction protocols. A combination of experimental studies and high-level DFT calculations revealed interesting mechanistic insights of this seemingly simple reaction. 5 6 ASSOCIATED CONTENT Supporting InformationThe Supporting Information is available free of charge on the ACS Publications website: Experimental details and spectroscopic data for all products, full Gaussian reference, Cartesian coordinates, electronic and free energies.

The alternating physical properties, especially melting points, of α,ω-disubstituted n-alkanes and their parent n-alkanes had been known since Baeyer’s report in 1877. There is, however, no general and comprehensive explanation for such a phenomenon. Herein, we report the synthesis and examination of a series of novel ω-phenyl n-alkyl tropylium tetrafluoroborates, which also display alternation in their physicochemical characters. Despite being organic salts, the compounds with odd numbers of carbons in the alkyl bridge exist as room temperature ionic liquids. In stark contrast to this, the analogues with even numbers of carbons in the linker are crystalline solids. These solid nonconjugated molecules exhibit curious photoluminescent properties, which can be attributed to their ability to form through-space charge-transfer complexes to cause crystallization-induced emission enhancement. Most notably, the compound with the highest photoluminescent quantum yield in this series showed an unusual arrangement of carbocationic dimer in the solid state. A combination of XRD analysis and ab initio calculations revealed interesting insights into these systems.

Tetrabenzo[5.7]fulvalene has been proven to be an outstanding aggregation-induced emission fluorophore.