Photochemical C-H Arylation of Napthoquinones Using Eosin Y

A visible-light-mediated C-H arylation of substituted 1,4-napthoquinones (1,4-SNQ) and 1,2-napthoquinone (1,2-NQ) with diazonium salt using a photocatalyst eosin Y at room temperature in a single step (isolated yield of ≥75%) is described in this report. The rate-determining step of the reaction is aryl radical generation, which was trapped by high-resolution mass spectrometry. Cost-effectiveness, operational simplicity, a short reaction time, high atom economy, and a good yield make this photoredox-mediated process a valuable alternative to the transition-metal (Fe, Cu, Pd, etc.)-catalyzed reaction.

The Different Facets of Metal-Catalyzed C-H Functionalization Involving Quinone Compounds

Metal-catalysed C-H functionalization has emerged as a powerful platform for the derivatization of quinones, a class of compounds with wide-ranging applications. This review organises and discusses the evolution of this chemistry from early Fujiwara-Moritani reactions, through to modern directing-group assisted C-H functionalization processes, including C-H functionalization reactions directed by the quinone ring itself. Mechanistic details of these reactions are provided to afford insight into how the unique reactivity of quinoidal compounds has been leveraged in each example.

Total Synthesis of the Antitumor-Antitubercular 2,6'-Bijuglone Natural Product Diospyrin and Its 3,6'-Isomer

The 2,6'-bijuglone natural product diospyrin and its unnatural 3,6'-isomer idospyrin have been synthesized in seven steps each from N,N-diethylsenecioamide in overall yields of 12% and 13%, respectively. The syntheses diverge from ramentaceone (7-methyljuglone) and include a key Suzuki-Miyaura cross-coupling. Diospyrin, idospyrin, and several synthetic precursors exhibit potent and selective cytotoxicity to the murine myeloma NS-1 cell line over neonatal foreskin cells.

Iron-mediated site-selective oxidative C–H/C–H cross-coupling of aryl radicals with quinones: synthesis of β-secretase-1 inhibitor B and related arylated quinones

Phenoxy radicals were converted intoparasite selectiveC-aryl radicals and coupled with quinones, using an inexpensive FeCl₃–K₂S₂O₈system, to obtain several arylated quinones, in good to moderate yields.

Metal-free, air-promoted, radical-mediated arylation of benzoquinone with phenylhydrazines

An efficient, economic, and air-promoted metal-free method for direct arylation of benzoquinone with phenylhydrazines was developed. This approach leads to the formation of corresponding [1,1′-biphenyl]-2,5-dione derivatives as biological and pharmaceutical materials of interest in good yields, under mild reaction conditions, and at ambient temperature.

A Single-Step Palladium-Catalysed Synthesis of Naphtho[2,3-b]Benzofuran-6,11-Diones and 2-(Hydroxyphenyl)Naphthalene-1,4-Diones

Palladium-catalysed competitive three-component C–H functionalisation reactions and cascade coupling ring-closing reactions of quinones with iodophenols in dihaloalkanes are described. During initial attempts to conduct C–H functionalisation reactions of quinones with iodophenols in dihaloalkanes, surprisingly a three-component C–H functionalisation reaction was discovered. Furthermore, as the reaction of chloroquinones with iodophenols was in progress, another surprising cascade coupling with ring closure was achieved. This provided an efficient single-step synthesis of naphtho[2,3- b]benzofuran-6,11-diones.