Benzoannellated Fenestranes Bearing para‐Terphenyl Units

• Published in: European journal of organic chemistry Vol. 2021; no. 46; pp. 6435 - 6449
• Main Authors: Seifert, Monika, Barth, Dieter, Kuck, Dietmar
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 14.12.2021; Wiley Subscription Services, Inc
• Subjects: Chemistry; Chemistry, Organic; Cyclization; Fenestranes; Physical Sciences; Polycycles; Science & Technology; Spiro compounds; Tribenzotriquinacenes; KEY BUILDING-BLOCKS; CHIRALITY-ASSISTED SYNTHESIS; BENZOANELLATED CENTROPOLYQUINANES; Fenestranes; Tribenzotriquinacenes; REGIOSELECTIVE FUNCTIONALIZATION; Polycycles; HOST-GUEST COMPLEXES; SOLID-STATE; CYCLOHEPTATRIENE RING FORMATION; Cyclization; COMPUTATIONAL SIMULATIONS; BUCKYBALL JOINTS SYNTHESIS; Spiro compounds; C-3V-SYMMETRICAL TRIBENZOTRIQUINACENES
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.202101222

The 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. Sterically crowded tribenzofenestranes, such as the fourfold ortho‐phenylated derivatives I and II, were synthesized in an attempt to explore a route to warped nanographenes bearing a tribenzotriquinacene or a [5.5.5.5]fenestrane core.