Benzannelated [2.2]paracyclophanes: synthesis and electronic properties

Abstract

Mono-and dibenzoannelated [2.2]paracyclophanes 12 and 1 were synthesized by palladium-catalyzed twoand four-fold alkenylation of vicinal di-and tetrabromides 5 and 6, respectively, and subsequent electrocyclization/ dehydrogenation of the resulting (E,Z,E)-trienes. Further extensions of the annelated ring systems, leading to the tetrahydronaphthalene derivative 15, the bis-terphenylene derivative 16, and the benzobis[2.2]paracyclophane 18, were achieved through derivatization of suitable substituents introduced with the alkene coupling component. Mono-and polyanions of some derivatives were generated and studied by ESR, E N D O R , and N M R spectroscopy, as well as by cyclic voltammetry. The assembly of mutually orthogonal r-systems in arene annelated [2.2]paracyclophanes allows the reversible incorporation of up to six additional electrons per molecule, which is the upper limit for hydrocarbons reported to date. Recently, we developed a general method for annelating sixmembered carbocycles onto 1 ,2-dibromocycloalkenes1 ' by Heck-type12 alkenylation and subsequent cyclization/dehydrogenation of the resulting (E,Z,E)-1,3,5-trienes. Preliminary studied3 had previously established that this protocol is applicable to vicinal dibromoalkenes derived from (3) Jacobson, N.; Boekelheide, V.

Ultrafast photoinduced electron transfer in face-to-face charge-transfer π-complexes of planar porphyrins and hexaazatriphenylene derivatives

“… b Reported value in dimethylamine/THF. 40 c Reported value. 41 d Determined by differential pulse voltammetry (DPV) in THF.…”

Multiple Vinylation of Tribenzotriquinacenes and Fenestrindanes at Their Aromatic Peripheries by Use of Nájera’s Catalyst

“…Attempts to achieve cyclodehydrogenation of 5a to generate the corresponding hexaphenyl-substituted trinaphthotriquinacene proved to be unsuccessful. Thus, heating of 5a with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) in xylene [32] under reflux for two days did not give any conversion to dehydrogenation products.…”

Indeno[1,2‐b]fluorene‐Based [2,2]Cyclophanes with 4n/4n and 4n/[4n+2] π Electrons: Syntheses, Structural Analyses, and Excitonic Coupling Properties

“…The chemistry of PCP and its derivatives has been intensively investigated, and recent reviews have elucidated their scientific importance and (potential) applications in optoelectronics and asymmetric synthesis, as well as being synthetic building blocks for optically active π‐stacked molecules . Expanding the π system of PCP either horizontally or vertically diversifies its properties, as exemplified by anti ‐[2.2](1,4)pentacenophane (PP), six‐layered PCP (SPCP,) and bis(triphenyleno)[2.2]paracyclophane‐1,9‐diene (BTPD) . Bisquinoid cyclophane (BQCP), having a rare 4 n /4 n π‐electron system, was generated in situ from the corresponding tetraimidazole by the stepwise absorption of two photons, and was recently found to exhibit interesting photophysical properties .…”