Retro‐Friedel–Crafts‐Type Acidic Ring‐Opening of Triptycenes: A New Synthetic Approach to Acenes

Abstract

This study finds that triptycenes can undergo ring opening solely after acid treatment. Triptycenes have ar igid and stable framework that enables them to act as the core structure for multifunctional molecules. Thus, their skeletal transformation is unusual and remains untapped in organic synthesis. We have found that ring opening of the triptycene scaffold occurs under acidic conditions in ar etro-Friedel-Crafts fashion to give the corresponding anthrone product. This simple yet overlooked reaction allows triptycene to serve as a" reactive unit". We also used this ring-opening reaction to synthesize tetracene, further demonstrating the potential of the reaction for the preparation of functionalized acenes.

Synthesis of Neocannabinoids Using Controlled Friedel–Crafts Reactions

“…29 Overall, this data confirmed that the generation of 3 from 6 (cf. Table 2) likely proceeds via an intermolecular retro-Friedel Crafts/Friedel−Crafts process 30 and not an intramolecular rearrangement pathway.…”

Mild and scalable synthesis of phosphonorhodamines

“…evidenced by the degradation of the triarylmethane intermediates in the presence of acid. 32 Precipitation from the reaction medium drives reaction progression and contributes to the near quantitative yields. For more soluble intermediates, like 13, performing the reaction under an inert atmosphere improves the yield, by avoiding premature oxidation to the nal rhodamine, which would otherwise complicate purication at this stage (Table 1).…”

Synthesis of [1]Benzothieno[2,3-b][1]benzothiophenes from 3-Arylbenzo[b]thiophenes through Iodine-Mediated Sulfur Insertion Reaction

“…1 H NMR analysis of the crude mixture showed that a small amount of 2a was generated in addition to 2b . Therefore, to suppress the unexpected demethylation, we reduced the amount of iodine from 7 equiv to 4 equiv . As a result, 2b was obtained in 72% yield.…”