Wavelength-Gated Photochemical Synthesis of Phenalene Diimides.

Florian Feist,John C Mcmurtrie,Christopher Barner‐Kowollik,James P Blinco,Aaron S Micallef,Susanna V Kunz,Aidan J Brock,Tanja Weil,Sarah L Walden,Jessica Alves

doi:10.1002/anie.202016632

Abstract

Herein, we pioneer a wavelength‐gated synthesis route to phenalene diimides. Consecutive Diels–Alder reactions of methylisophthalaldehydes and maleimides afford hexahydro‐phenalene‐1,6‐diol diimides via 5‐formyl‐hexahydro‐benzo[f]isoindoles as the intermediate. Both photoreactions are efficient (82–99 % yield) and exhibit excellent diastereoselectivity (62–98 % d.r.). The wavelength‐gated nature of the stepwise reaction enables the modular construction of phenalene diimide scaffolds by choice of substrate and wavelength. Importantly, this synthetic methodology opens a facile avenue to a new class of persistent phenalenyl diimide neutral radicals, constituting a versatile route to spin‐active molecules.

Highlights

Polycyclic aromatic-imides are a ubiquitous structural motif owing to the combination of an electron-rich aromatic system and a strong electron-withdrawing moiety.[1]
We demonstrate the wavelength-gated formation of o-QDMs involving a single methyl group and trapping these highly reactive intermediates with maleimide
The methodology presented combines the high efficiency of click chemistry with the spatiotemporal control of light-induced reactions, enabling the wavelength-gated generation of heterobifunctional phenalene diimides

Summary

Introduction

Polycyclic aromatic (di)-imides are a ubiquitous structural motif owing to the combination of an electron-rich aromatic system and a strong electron-withdrawing moiety.[1]. The click-chemistry concept introduced by Kolb, Finn, and Sharpless focusses on combining molecular building blocks via highly efficient ligation reactions.[14] The modular nature of this approach has been demonstrated in many studies, especially in the fields of bio-[15] and polymer chemistry.[16] The click concept can be further enhanced by exploiting the spatio-temporal control of photochemical reactions.[17] Already an indispensable tool in organic synthesis,[18] photochemistry provides additional spatial and temporal control over chemical transformations, enabling the fabrication of nano-structured materials.[19] By exploiting the energy contained in different wavelengths of light, distinct reaction pathways can be accessed, affording the ability to perform complex synthetic steps independently, which would be difficult using conventional reaction conditions.[20]. Our concise approach eliminates the barrier of complex synthetic procedures in organic spin chemistry[6a] via the judicious design and tailoring of electronic spin structures

Results and Discussion

Conclusion

Conflict of interest

Barner-Kowollik*