Categories: Synthesis of O-Heterocycles >
Synthesis of Chromones and Flavones
Recent Literature
A highly efficient and selective palladium-catalyzed ligand-free
cyclocarbonylation reaction of o-iodophenols with terminal acetylenes
under atmospheric CO pressure affords diversified chromones in very good yields.
The use of a phosphonium salt ionic liquid as the reaction medium enhances the
efficiency of the cyclocarbonylation reaction.
Q. Yang, H. Alper, J. Org. Chem., 2010,
75, 948-950.
A palladium complex of
1,3,5,7-tetramethyl-2,4,8-trioxa-6-phenyl-6-phosphaadamantane is an effective
catalyst for a sequential microwave-assisted Sonogashira and carbonylative
annulation reaction to give substituted flavones.
E. Awuah, A. Capretta, Org. Lett., 2009,
11, 3210-3213.
E. Awuah, A. Capretta, Org. Lett., 2009,
11, 3210-3213.
A Pd-catalyzed copper-free carbonylative Sonogashira coupling reaction at
room temperature was achieved
by using water as a solvent
under balloon pressure of CO with Et3N as a base. The developed method was
successfully applied to the synthesis of flavones.
B. Liang, M. Huang, Z. You, Z. Xiong, K. Lu, R. Fathi, J. Chen, Z. Yang, J. Org. Chem., 2005, 70, 6097-6100.
Chromone derivatives were synthesized from 2,3-allenoic acids and benzynes in
good yields under mild conditions. The benzyne intermediate undergoes
1,2-addition with the carbonyl group, followed by ring opening, conjugate
addition, and protonolysis to afford chromone derivatives. This protocol allows
the diversity due to the substituent-loading capability of 2,3-allenoic acids as
well as benzynes.
G. Chai, Y. Qiu, C. Fu, S. Ma, Org. Lett., 2011,
13, 5196-5199.
A mild ICl-induced cyclization of heteroatom-substituted alkynones provides
a simple, highly efficient approach to various 3-iodochromones,
iodothiochromenones, iodoquinolinones and analogues in good to excellent
yields. Subsequent palladium-catalyzed transformations afford a rapid
increase in molecular complexity.
C. Zhou, A. V. Dubrovsky, R. C. Larock, J. Org. Chem., 2006, 71,
1626-1632.
