Synthesis of fluorenones
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.
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.