Benzoannellated Fenestranes Bearing para‐Terphenyl Units

Abstract

In memory of Klaus HafnerThe synthesis of several centrotriindanes bearing ortho-phenyl groups in the sterically constricted bay regions is described. The classical three-step sequence including twofold cyclodehydration of the corresponding 2,2-dibenzyl-1,3-indanediols afforded an angular difuso-triidane and several all-cis-tribenzo[5.5.5.6] fenestranols equipped with two or four ortho-phenyl groups. In contrast to the construction of these conformationally flexible centrotriindanes, attempts to synthesize ortho,ortho-diphenyl-substituted tribenzotriquinacenes failed due to the increased rigidity of the TBTQ skeleton. The high steric load imposed by the para-terphenyl moieties affects the spirocyclization between 1,3-indanedione and 1,5-di-(para-2'-terphenylyl)pentadienone, kinetic control of which is critical to access the all-cis-tribenzo [5.5.5.6]fenestrane framework. In contrast, the corresponding tetraphenyl-cis,cis,cis,trans-tribenzo[5.5.5.6]fenestranol is easily accessible.

Donor‐Acceptor Tribenzotriquinacene‐Based Molecular Wizard Hats Bearing Three ortho‐Benzoquinone Units

“…The considerable steric constraint of aryl groups at the ortho ‐positions of the TBTQ framework has been observed many times [12,16,17,24] . This arrangement gives rise to (i) characteristic upfield shift of the ortho ‐proton of the indane wing opposite to the given ortho ‐aryl residue, and (ii) decreased rates of rotation of such aryl groups.…”

“…The considerable steric constraint of aryl groups at the ortho-positions of the TBTQ framework has been observed many times. [12,16,17,24] This arrangement gives rise to (i) characterristic upfield shift of the ortho-proton of the indane wing opposite to the given ortho-aryl residue, and (ii) decreased rates of rotation of such aryl groups. In the present case, both the 1 H and 13 C NMR spectra of the 1,5,9-triaryl-TBTQ derivatives 9 and 14 exhibited line broadening at ambient temperature.…”

“…In the past decades, the chemistry of tribenzotriquinacene (TBTQ) has been developed in a large variety of ways [1–12] . Besides functionalization of the four bridgeheads and the six outer (peripheral) arene positions, such as in the key derivative 1 (Figure 1), [13,14] activation of the six inner arene positions offer a great potential, especially for π‐extension of the bowl‐ (or hat‐) shaped polyaromatic TBTQ framework [1,5a,15] .…”

“…In the past decades, the chemistry of tribenzotriquinacene (TBTQ) has been developed in a large variety of ways. [1][2][3][4][5][6][7][8][9][10][11][12] Besides functionalization of the four bridgeheads and the six outer (peripheral) arene positions, such as in the key derivative 1 (Figure 1), [13,14] activation of the six inner arene positions offer a great potential, especially for π-extension of the bowl-(or hat-) shaped polyaromatic TBTQ framework. [1,5a,15] Threefold bridging of the (extended) bays by ortho-phenylene units, giving wizard-hat-shaped congeners, and full annulation with a nonaphenylene jacket, like in 2, have been achieved in recent years.…”