The Development of Synthetic Routes to 1,1,n,n‐Tetramethyl[n](2,11)teropyrenophanes

• Published in: European journal of organic chemistry 2019-07, Vol.2019 (28), p.4546-4560
• Main Authors: Unikela, Kiran Sagar, Merner, Bradley L., Ghasemabadi, Parisa Ghods, Warford, C. Chad, Qiu, Christopher S., Dawe, Louise N., Zhao, Yuming, Bodwell, Graham J.
• Format: Article
• Language: English
• Subjects: Alkylation; Bridge construction; Crystal structure; Cyclophanes; Nonplanar aromatic compounds; Polycyclic aromatic hydrocarbons; Substitution reactions; Teropyrene
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.201900707

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°. BIG BEND chimes in – this is not second hand news! Every minute detail of the synthesis of a striking series of 1,1,n,n‐tetramethyl[n](2,11)teropyrenophanes (n=7–9) is described. The end‐to‐end bend in the teropyrene system clocks in at as much as 177.9°.