Extremely strained paracyclophanes

Volume Change during Thermal [4 + 4] Cycloaddition of [2.2] (9,10)Anthracenophane

“…Paracyclophanes, another example containing unusual CC distances, are of chemical interest due to their unconventional structures and photoisomerization reactivities. , Applications in the fields of chiral catalysis, , electronic materials, and optical switches have broadened this interest. Structural anomalies in paracyclophanes include nonplanar distorted aromatic rings and unusual distances between sp 3 -hybridized carbons.…”

“…13 Paracyclophanes, another example containing unusual CC distances, are of chemical interest due to their unconventional structures and photoisomerization reactivities. 14,15 Applications in the fields of chiral catalysis, 16,17 electronic materials, 18 and optical switches 19 aromatic rings and unusual distances between sp 3 -hybridized carbons. While the structure of paracyclophanes has been studied experimentally 20−23 and theoretically 24−29 with a variety of methods, the reaction paths of photoisomerization have been largely ignored.…”

DFT Study of [2.2]-, [3.3]-, and [4.4]Paracyclophanes: Strain Energy, Conformations, and Rotational Barriers

“…13 The twisting within 1 has been disputed by Lyssenko, Antipin, and Antonov, who find that at 100 K the molecule possesses D 2h symmetry. 19 The next larger symmetric member of the series, [3.3]paracyclophane (2), is also a known compound 20 and its X-ray structure has been published; the so-called trans isomer 2t was observed in the solid state. 21 Dodziuk et al 22 have examined the solution phase NMR spectra of 2 and interpreted it as resulting from an equilibrium of the trans 2t and cis 2c isomers, with the cis isomer predominant.…”

“…The paracyclophanes are of interest as they test our notions of strain and aromaticity, − two bedrock concepts of organic chemistry. , When the alkyl chains connecting the phenyl rings are short, the phenyl rings are distorted from planarity, inducing loss of aromaticity. Larger distortions of the phenyl rings are avoided by introducing some strains into the alkyl chains.…”

A Novel Strained Undecadiyne Cyclophane with Interesting Dienophilic Character

“…The synthesis and design of new cyclophanes and assorted cage compounds with novel shapes and supramolecular geometries 3 continue to be topics of current interest. We have established previously that the para -cyclophanes with eneyne bridges composed of double bonds and/or benzene rings may be readily prepared by sequential palladium(0)- and copper(II)-mediated couplings.…”