O‐Acylative Vinylation of Cyclodextrin‐Based [3]Rotaxane Towards Rotaxane Crosslinkers

• Published in: European journal of organic chemistry 2023-03, Vol.26 (12), p.n/a
• Main Authors: Akae, Yosuke, Takata, Toshikazu
• Format: Article
• Language: English
• Subjects: Acylation; Anhydrides; Crosslinking; Cyclodextrins; MALDI-TOF-MS; NMR; Nuclear magnetic resonance; O-acylation; Reagents; Rotaxanes; Steric hindrance; vinyl-group introduction
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.202300009

The acylation of a cyclodextrin‐based [3]rotaxane was implemented with anhydride reagents following a facile procedure. Methacrylic anhydride facilitated the introduction of a vinyl‐group into the rotaxane structure toward achieving a crosslinker. Interestingly, only a few methacrylic units were attached to the cyclodextrin at reaction temperatures of up to 60 °C even with an excess amount of the reagent, probably due to steric hindrance. Therefore, the number of vinyl groups on the [3]rotaxane framework was easily controlled to be approximately two units via a simple random acylation, which worked effectively as a facile synthesis route for the rotaxane crosslinker. The acylation behavior was investigated in detail by NMR and MALDI‐TOF‐MS analyses. Such a proposed approach will help overcome the trade‐off between convenience and utility associated with the mono‐modification of cyclodextrins. Random acylation of cyclodextrin (CD) was revealed to highly depend on the steric hindrance of the reagent. Based on this phenomenon, the facile synthesis of a [3]rotaxane crosslinker was implemented via random methacrylation without any demanding synthetic process. The mono‐modification of CD is known to be useful but demanding work; however, we propose a novel process for overcoming this trade‐off, promoting both convenience and usefulness.