Categories: Synthesis of O-Heterocycles >
Synthesis of 2-pyrones
Recent Literature
An electrophilic pyrone derivative, which can be readily prepared on a multigram
scale, undergoes metal-catalyzed cross-coupling reactions with a variety of
nucleophiles to yield 3-substituted-2-pyrones.
F. Frébault, M. T. Oliveira, E. Wöstefeld, Nuno Maulide, J. Org. Chem., 2010,
75, 762-7695.
A palladium-catalyzed cross-coupling reaction of cyclic vinyldiazo ester with
aryl iodides provides various 3-aryl-2-pyrones in good yields with high
functional group tolerance. The resulting 3-aryl-2-pyrones can be used as diene
components in Diels-Alder reactions.
J. Huang, L. Li, H. Chen, T. Xiao, Y. He, L. Zhou, J. Org. Chem.,
2017, 82, 9204-9209.
Sequential activation of terminal alkynes and propiolic acids by gold(I)
catalysts yields α-pyrones in good yields. Novel cascade reactions involving
propiolic acids are reported that give rise to α-pyrones with different
substitution patterns.
T. Luo, M. Dai, S.-L. Zheng, S. L. Schreiber, Org. Lett., 2011,
13, 2834-2836.
The oxyindation of carbonyl-ene-yne compounds with indium trihalides provides
di-, tri-, and tetrasubstituted 2-pyrones bearing a carbon-indium bond. The
metalated 2-pyrones can be oxidized or cross-coupled to multifunctionalized
2-pyrones.
T. Yata, Y. Kita, Y. Nishimoto, M. Yasuda, J. Org. Chem., 2019, 84,
14330-14341.
A gold(I)-catalyzed rearrangement of β-alkynylpropiolactones enables a
straightforward synthesis of substituted α-pyrones in good yields.
T. Dombray, A. Blanc, J.-M. Weibel, P. Pale, Org. Lett., 2010,
12, 5362-5365.
Synergistic use of electrochemistry and organometallic catalysis enables a
site-selective vinylic C-H functionalization of acrylic acids with alkynes
affording α-pyrones with very good yields in an undivided cell. Importantly,
common chemical oxidants such as Ag(I) or Cu(II) did not give significant
amounts of the desired product in the absence of electrical current under
otherwise identical conditions.
Q.-L. Yang, Y.-K. Xing, X.-Y. Wang, H.-X. Ma, X.-J. Weng, X. Yang, H.-M. Guo,
T.-S. Mei, J. Am. Chem. Soc.,
2019, 141, 18970-18976.
Polymer-supported DMAP catalyzes a one-pot synthesis of diversely substituted
α-pyrones. The cascade approach involves C5 conjugate addition of 5H-oxazol-4-ones
to α,β-unsaturated-β-ketoesters followed by lactonization/elimination.
A. Jain, A. Kumari, S. K. Saha, K. Shukla, A. Chauhan, R. K. Metre, N. K.
Rana, J. Org. Chem., 2023, 88,
11346-11351.
A N-heterocyclic carbene catalyzes a formal [3 + 3] annulation of alkynyl
esters with enolizable ketones to provide functionalized 2H-pyran-2-ones
in a highly regioselective manner. This simple protocol offers a broad substrate
scope and mild metal-free conditions.
Z. Liang, J. Li, L. Wang, Z. Wei, J. Huang, X. Wang, D. Du, J. Org. Chem., 2023, 88,
1836-1843.
An efficient synthesis of 6-substituted 3-(alkoxycarbonyl)-5-aryl-α-pyrones
consists of an addition-elimination reaction between benzyl ketone derivatives
and dimethyl methoxymethylenemalonate, and an acid-catalyzed condensation
reaction. The synthesis is applicable to various multiubstituted α-pyrones in
very good yields.
T. Miura, S. Fujioka, N. Takemura, H. Iwasaki, M. Ozeki, N. Kojima, M. Yamashita, Synthesis, 2014, 46,
496-502.
A ruthenium-catalyzed regioselective intermolecular multistep homo- and
heterodimerization of substituted propiolates provides α-pyrone-5-carboxylates
and α-pyrone-6-carboxylates. The proposed mechanism is strongly supported by
experimental evidence.
R. Manikandan, M. Jeganmohan, Org. Lett., 2014,
16, 652-655.
Ruthenium catalyzes an efficient three-component cascade reaction of acrylic
acids, ethyl glyoxylate, and p-toluenesulfonamide to provide pyranones. A
nucleophilic addition of the vinylic C-H bond to the aldehyde is followed by an
intramolecular cyclization and a second insertion to provide substituted
butenolides. The elimination of sulfonamides occurs at higher temperature to
give the pyranones.
S. Yu, C. Hong, Z. Liu, Y. Zhang, Org. Lett.,
2022, 24, 4871-4875.
Addition of a catalytic amount of Cy2NH·HX improves the rate and
yields for cyclization reactions of o-(alkynyl)benzoates in the presence
of a stoichiometric amount of copper(II)halide to give 4-haloisocoumarins. Under
the standard reaction conditions, various 4-haloisocoumarins are provided in
good yield.
Y. Liang, Y.-X. Xie, J.-H. Li, Synthesis, 2007,
400-406.
An efficient intramolecular annulation of Morita-Baylis-Hillman (MBH) alcohols
of propiolaldehydes in the presence of ICl or PhSeSePh/PhSSPh-CuCl2
provides a wide variety of iodinated or chalcogenated 3-(chloromethyl)-2-pyrones
in good yields. The chloromethyl group can easily be converted to other
functionalities.
C. R. Reddy, A. D. Patil, Org. Lett., 2021, 23,
4749-4753.