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 towards 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.
Supporting Information for Photochemical α-Aminonitrile Synthesis using Zn-Phthalocyanines as Near-Infrared Photocatalysts
Supporting information containing additional procedures, mechanistic investigations, optimization studies, and spectra