A concise synthetic approach to 1,1,n,n‐tetramethyl[n](2,11)teropyrenophanes has been developed. It involves the construction of triply‐bridged pyrenophanes, during which the three bridges are installed successively using Friedel‐Crafts alkylation, Wurtz coupling and McMurry reactions. At the same time, the innate regiochemical preferences of pyrene toward electrophilic aromatic substitution are relied upon to control the substitution pattern. A cyclodehydrogenation reaction is then employed to generate the teropyrene system directly in a nonplanar conformation. The crystal structure of 1,1,7,7‐tetramethyl[7](2,11)teropyrenophane was determined and the teropyrene system was found to have an end‐to‐end bend angle of 177.9°.
Anew synthetic strategy (contractive annulation) for the synthesis of highly strained cyclophanes has been conceived and its viability has been demonstrated through an ine-step synthesis of [2](6,1)naphthaleno[1]paracyclophane from [2.2]paracyclophane. Scheme 1. Existing aromatization-based approach to the syntheses of highly strained cyclophanesand selected examples of its use. Scheme 2. Contractive annulation strategy for simultaneously growing the aromatic component of acyclophane and contracting its bridge. DDQ = 2,3-dichloro-5,6-dicyano-1,4-benzoquinone,D MSO = dimethylsulfoxide, Ts = 4-toluenesulfonyl.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.
A new synthetic strategy (contractive annulation) for the synthesis of highly strained cyclophanes has been conceived and its viability has been demonstrated through a nine‐step synthesis of [2](6,1)naphthaleno[1]paracyclophane from [2.2]paracyclophane.
1,2:3,4:7,8:9,10‐Tetrabenzocoronene (TBC) is a highly π‐conjugated polycyclic aromatic hydrocarbon (PAH) with an intriguing nonplanar, twisted molecular shape featuring two [4]helicene subunits on the opposite sides of the molecule. In this study, we examined the electronic substituent effects on the molecular properties of a series of TBC derivatives by density functional theory (DFT) and time‐dependent DFT (TD‐DFT) computational analysis at the B3LYP/6‐31G(d) and TD‐B3LYP/6‐311 + G(d,p) levels. The equilibrium geometries for the stable conformers of the TBC derivatives in the ground singlet state (So) and related transition states were optimized to obtain the energy barriers associated with the interconversion among these conformers. Variations of aromatic character for these compounds were evaluated by nucleus‐independent chemical shift (NICS) calculations, while the frontier molecular orbital (FMO) energies and the vertical electronic absorption and emission energies were calculated. The calculated absorption and emission spectra of these TBC derivatives show good correlations with the Hammett substituent constant (σ). Overall, our study has demonstrated that the attachment of electron‐donating/withdrawing substituents to the edges of TBC can exert significant effects on the structural, electronic, and photophysical properties. Understanding of the substitution effects on TBC provides valuable insight for the design and development of novel PAH‐based organic electronic materials and devices.
C-B bond forming reactions are important methodologies in modern synthetic chemistry, since many borylated organic substrates, ranging from alkanes and alkenes to arenes and heteroarenes, are useful intermediates for the...
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