Direct Photocatalyzed Hydrogen Atom Transfer (HAT) for Aliphatic C–H Bonds Elaboration

• Published in: Chemical reviews Vol. 122; no. 2; pp. 1875 - 1924
• Main Authors: Capaldo, Luca, Ravelli, Davide, Fagnoni, Maurizio
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 26-01-2022
• Subjects: Additives; Aliphatic compounds; Chemical bonds; Covalent bonds; Hydrogen; Hydrogen - chemistry; Hydrogen bonds; Ketones; Molecular Structure; Organic compounds; Polyoxometallates; Porphyrins; Porphyrins - chemistry; Review; Yttrium
• ISSN: 0009-2665; 1520-6890
• DOI: 10.1021/acs.chemrev.1c00263

Direct photocatalyzed hydrogen atom transfer (d-HAT) can be considered a method of choice for the elaboration of aliphatic C–H bonds. In this manifold, a photocatalyst (PCHAT) exploits the energy of a photon to trigger the homolytic cleavage of such bonds in organic compounds. Selective C–H bond elaboration may be achieved by a judicious choice of the hydrogen abstractor (key parameters are the electronic character and the molecular structure), as well as reaction additives. Different are the classes of PCsHAT available, including aromatic ketones, xanthene dyes (Eosin Y), polyoxometalates, uranyl salts, a metal-oxo porphyrin and a tris­(amino)­cyclopropenium radical dication. The processes (mainly C–C bond formation) are in most cases carried out under mild conditions with the help of visible light. The aim of this review is to offer a comprehensive survey of the synthetic applications of photocatalyzed d-HAT.