Categories: Synthesis of N-Heterocycles > benzo-fused N-Heterocycles >
Synthesis of dihydroquinolinones
The combination of SmI2/H2O/MeOH promotes a selective reduction of quinolin-2(1H)-ones to afford 3,4-dihydroquinoline-2(1H)-ones under mild conditions with good to excellent yields.
D. Xie, S. Zhang, J. Org. Chem., 2022, 87, 8757-8763.
A Rh/Pd/Cu catalyst system led to an efficient one-pot synthesis of dihydroquinolinones without any intermediate workup. The conjugate-addition/amidation/amidation reaction sequence is highly modular, divergent, and practical.
L. Zhang, L. Sonaglia, J. Stacey, M. Lautens, Org. Lett., 2013, 15, 2128-2131.
With the proper choice of palladium catalyst, ligand, and base, five-, six-, and seven-membered rings are formed efficiently from secondary amide or secondary carbamate precursors.
B. H. Yang, S. L. Buchwald, Org. Lett., 1999, 1, 35-37.
[Ru(p-cymene)(L-proline)Cl] catalyzes a cyclization of 1,4,2-dioxazol-5-ones to form dihydroquinoline-2-ones in excellent yields with excellent regioselectivity via a formal intramolecular arene C(sp2)-H amidation. The reactions of the 2- and 4-substituted aryl dioxazolones proceed initially through spirolactamization via electrophilic amidation at the arene site.
W. Sun, C.-H. Ling, C.-M. Au, W.-Y. Yu, Org. Lett., 2021, 23, 3310-3314.
A metal- and additive-free photoredox cyclization of N-arylacrylamides provides dihydroquinolinones in good yields in the presence of the organic light-emitting molecule 4CzIPN as photocatalyst.
Z. Liu, S. Zhong, X. Ji, G.-J. Deng, H. Huang, Org. Lett., 2022, 24, 349-353.
The P-chiral monophosphorus ligand BI-DIME enables an efficient, palladium-catalyzed, decarboxylative [4 + 2]-cycloaddition of 4-vinyl benzoxazinanones with carboxylic acids to provide structurally diverse 3,4-dihydroquinolin-2-ones bearing two contiguous stereogenic centers in good yields with very good stereoselectivities.
J.-H. Jin, H. Wang, Z.-T. Yang, W.-L. Yang, W. Tang, W.-P. Deng, Org. Lett., 2018, 20, 104-107.
In an asymmetric [4+2] cycloaddition of vinyl benzoxazinanones with a variety of ketene intermediates via sequential visible-light photoactivation and palladium catalysis, the traceless and transient generation of ketenes from α-diazoketones through visible-light-induced Wolff rearrangement is important for the success of the palladium catalysis.
M.-M. Li, Y. Wei, J. Liu, H.-W. Chen, L.-Q. Lu, W.-J. Xiao, J. Am. Chem. Soc., 2017, 139, 14707-14713.
DBU mediates a formal [4+2] annulation reaction of aza-ortho-quinone methides (generated from o-chloromethyl anilines) with enolates (formed from azlactones) to provide biologically significant 3,4-dihydroquinolin-2(1H)-one derivatives in good yields. This reaction offers use of readily accessible starting materials, broad substrate scope, and mild reaction conditions.
H. Ji, C. He, H. Gao, W. Fu, J. Xu, Synthesis, 2021, 53, 1349-1355.