Recent advances of 9-fluorenone in photoredox catalysis

Abstract

9-fluorenone has recently become a very effective photoredox catalyst for various chemical transformations. 9-fluorenone is very cheap and readily available, making it promising for versatile photocatalysts compared to transition metal complexes. This review provides a detailed account of synthetic transformations, including rearrangements, oxidations, C-H functionalization, Diels-Alder reactions, acylation, and alkylation, along with the mechanism of representative methodologies based on their general catalytic cycle utilizing 9-fluorenone as a photoredox catalyst. Additionally, the organic transformations discussed in this review align with green chemistry principles, as they avoid heavy metals, minimize waste, use cost-effective reagents, employ environmentally friendly solvents, and facilitate easy oxidation with O sub(2).