Categories: C-C Bond Formation > Arenes, Cyclic Compounds >

Synthesis of fluorenones

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Recent Literature

A Pd-catalyzed carbonylative multiple C-C bond formation enables an efficient route to various substituted fluoren-9-ones. The reaction proceeded smothly under a CO atmosphere, using commercially available aryl halides and arylboronic acids as substrates, in good yields with good functional-group compatibility.
J. Song, F. Wei, W. Sun, K. Li, Y. Tian, C. Liu, Y. Li, L. Xie, Org. Lett., 2015, 17, 2106-2109.

A new, anionic four-electron donor-based (type I) palladacycle-catalyzed sequential reaction of 2-bromobenzaldehydes with arylboronic acids based on the addition reaction, cyclization via C-H activation-oxidation sequence provides an efficient access to a variety of substituted fluorenones/indenofluorenediones from readily available starting materials.
T.-P. Liu, Y.-X. Liao, C.-H. Xing, Q.-S. Hu, Org. Lett., 2011, 13, 2452-2455.

A palladium-catalyzed cyclocarbonylation of o-halobiaryls enables a synthesis of various substituted fluoren-9-ones bearing either electron-donating or electron-withdrawing substituents in very high yields. This chemistry has been successfully extended to polycyclic and heterocyclic fluorenones.
M. A. Campo, R. C. Larock, Org. Lett., 2000, 2, 3675-3677.

ClCF₂COONa serves as a coupling partner in a Pd-catalyzed assembly of fluoren-9-ones by merging of C-H activation and difluorocarbene transfer. The current protocol provides fluoren-9-ones in high yields with excellent functional group compatibility.
X. Liu, H. Sheng, Y. Zhou, Q. Song, Org. Lett., 2021, 23, 2543-2547.

A photocatalyzed intramolecular cyclization of biarylcarboxylic acids with triphenylphosphine as an inexpensive and effective deoxygenative reagent provides fluorenones via formation of acyl radicals, which quickly undergo intramolecular radical cyclization. Reactions in the presence of air and continuous flow photoredox technology demonstrate the generality and practicality of this process.
Y. Li, W. Xu, C. Zhu, J. Xie, Synlett, 2021, 32, 387-390.

A rhodium-catalyzed intramolecular acylation of biarylcarboxylic acids enables an efficient approach to the synthesis of fluorenones. Using this procedure, fluorenones with various substituents can be synthesized in very good yields.
T. Fukuyama, S. Maetani, K. Miyagawa, I. Ryu, Org. Lett., 2014, 16, 3216-3217.

Photoredox catalysis enables an efficient deoxygenative radical cyclization reaction of biarylcarboxylic acids for the synthesis of fluorenones. This photocatalytic intramolecular acyl radical coupling reaction provides valuable fluorenone products with mild conditions, good yields, and good functional-group compatibility.
R. Ruzi, M. Zhang, K. Ablajan, C. Zhu, J. Org. Chem., 2017, 82, 12834-12839.

A pH-controlled polarity umpolung strategy enables a simple intramolecular aroylation of electron-rich arenes under mild conditions to provide different fluorenones, which are important building blocks for biological applications. Unlike previous acylation reactions involving nucleophilic aroyl radicals, this approach likely relies on in situ generated electrophilic aroyl radicals.
J. K. Laha, U. Gulati, Saima, T. Schulte, M. Breugst, J. Org. Chem., 2022, 87, 6638-6656.