Wavelength‐Gated Photochemical Synthesis of Phenalene Diimides

• Published in: Angewandte Chemie International Edition Vol. 60; no. 18; pp. 10402 - 10408
• Main Authors: Feist, Florian, Walden, Sarah L., Alves, Jessica, Kunz, Susanna V., Micallef, Aaron S., Brock, Aidan J., McMurtrie, John C., Weil, Tanja, Blinco, James P., Barner‐Kowollik, Christopher
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 26.04.2021; Wiley Subscription Services, Inc; John Wiley and Sons Inc
• Edition: International ed. in English
• Subjects: Chemistry; Chemistry, Multidisciplinary; Diels–Alder reaction; Diimide; Modular construction; ortho-quinodimethane; persistent neutral radicals; phenalene diimide; Photochemicals; Physical Sciences; Science & Technology; Stereoselectivity; Substrates; Wavelength; wavelength-gated synthesis; Alder reaction; wavelength-gated synthesis; STATE; COPOLYMERS; ortho-quinodimethane; persistent neutral radicals; Diels– DIELS-ALDER REACTION; CHEMISTRY; RADICALS; phenalene diimide; DERIVATIVES; O-QUINODIMETHANES; Diels-Alder reaction
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202016632

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. Methylisophthalaldehydes form two highly reactive ortho‐quinodimethane dienophiles in a step‐wise and wavelength gated fashion. Trapping with maleimides proceeds with high stereoselectivity under the formation of phenalene diimide scaffolds. Subsequent elimination and oxidation affords a new class of persistent phenalenyl diimide neutral radicals.