Photochemical α‑Aminonitrile Synthesis Using Zn-Phthalocyanines as Near-Infrared Photocatalysts

• Published in: Journal of organic chemistry Vol. 87; no. 9; pp. 5630 - 5642
• Main Authors: Grundke, Caroline, Silva, Rodrigo C, Kitzmann, Winald R, Heinze, Katja, de Oliveira, Kleber T, Opatz, Till
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 06-05-2022
• Subjects: Indoles - chemistry; Isoindoles; Organometallic Compounds - chemistry; Photosensitizing Agents; Zinc Compounds
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/acs.joc.1c03101

While photochemical transformations with sunlight almost exclusively utilize the UV–vis part of the solar spectrum, the majority of the photons emitted by the sun have frequencies in the near-infrared region. Phthalocyanines show high structural similarity to the naturally occurring light-harvesting porphyrins, chlorins, and mainly bacteriochlorins and are also known for being efficient and affordable near-infrared light absorbers as well as triplet sensitizers for the production of singlet oxygen. Although having been neglected for a long time in synthetic organic chemistry due to their low solubility and high tendency toward aggregation, their unique photophysical properties and chemical robustness make phthalocyanines attractive photocatalysts for the application in near-infrared-light-driven synthesis strategies. Herein, we report a cheap, simple, and efficient photocatalytic protocol, which is easily scalable under continuous-flow conditions. Various phthalocyanines were studied as near-infrared photosensitizers in oxidative cyanations of tertiary amines to generate α-aminonitriles, a synthetically versatile compound class.