Dynamic Self-Assembled Systems of Photoinert <i>N</i>-Propargyl Amides Enable Red-Light Supramolecular Photocatalysis

Photocatalysis offers a sustainable alternative in chemistry by leveraging light as a renewable energy source for environmentally friendly chemical transformations. However, its broader use is limited by a scarcity of catalysts effective under mild conditions and diverse light spectra, requiring innovative strategies beyond traditional designs. Supramolecular photocatalysis exemplifies such innovation, utilizing dynamic, self-assembled complexes to explore novel reaction pathways. This study introduces an approach involving photoinert N-propargyl benzamides, which assembled via chelation into a second-order inner metallic complex in the presence of KOtBu. These systems (λem = 502 nm, τ = 0.96 ns) harnessed visible red light (620–750 nm) to trigger a self-sustaining catalytic cycle. Under red light irradiation, the complex underwent a single-electron transfer (SET) from the counteranion to its building block, enabling the solvent-free synthesis of 2,5-disubstituted oxazoles with 100% atom economy. This reaction system effectively emulated the function of a photosynthetic reaction center. Its sustainability was demonstrated by a low E-factor of 0.28 and an atom efficiency of 88%, reflecting minimal waste generation.