Categories: C-C Bond Formation > Carbocyclic compounds > Cyclic enones
Synthesis of cyclohexenones
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Recent Literature
The use of allyl-palladium catalysis enables a one-step α,β-dehydrogenation of
ketones via their zinc enolates. The optimized protocol utilizes commercially
available Zn(TMP)2 as base and diethyl allyl phosphate as oxidant,
operates under salt-free conditions, and tolerates a diverse scope of
cycloalkanones.
D. Huang, Y. Zhao, T. R. Newhouse, Org. Lett.,
2018, 20, 684-687.
A cationic Rh(I)-catalyzed [5 + 1] cycloaddition of vinylcyclopropanes and CO
affords either β,γ-cyclohexenones as major products or α,β-cyclohexenones
exclusively, under different reaction conditions.
G.-J. Jiang, X.-F. Fu, Q. Li, Z.-X. Yu, Org. Lett., 2012,
14, 692-695.
Wittig reaction of aldehydes with (cyclopropylmethyl)triphenylphosphonium
bromide delivered alkenyl cyclopropanes. UV irradiation in the presence of
Fe(CO)5 converted these alkenyl cyclopropanes to 2-substituted
cyclohexenones. This approach enabled a three-step synthesis of the tricyclic
core of estrone methyl ether.
D. F. Taber, R. B. Sheth, J. Org. Chem., 2008,
73, 8030-8032.
The gold(I) complex MeAuPPh3 is a highly effective catalyst for the
hydrative cyclization of 1,6-diynes to yield 3-methyl hex-2-enone derivatives
with very good yield. A mechanism is proposed.
C. Zhang, D.-M. Cui, L.-Y. Yao, B.-S. Wang, Y.-Z. Hu, T. Hayashi, J. Org. Chem., 2008,
73, 7811-7813.
TFA-promoted exo carbocyclizations of nonterminal alkynals gave good to
excellent yields of exo cycloalkenones. On the other hand, terminal
5-alkynals gave endo carbocyclizations to cyclohexenones. These
carbocyclizations can be considered as tandem alkyne hydration/aldol
condensation processes.
C. González-Rodríguez, L. Escalante, J. A. Varela, L. Castedo, C. Sáa, Org. Lett., 2009,
11, 1531-1533.
Pd(DMSO)2(TFA)2 as a catalyst enables a direct
dehydrogenation of cyclohexanones and other cyclic ketones to the corresponding
enones, using O2 as the oxidant. α,β-Unsaturated carbonyl compounds
are versatile intermediates in the synthesis of pharmaceuticals and biologically
active compounds. The substrate scope includes heterocyclic ketones and several
natural-product precursors.
T. Diao, S. S. Stahl, J. Am. Chem. Soc., 2011,
133, 14566-14569.
Silyl enol ethers can serve as masked source of saturated ketones to derive
β-aryl enones and their derivatives by dehydrosilylation to generate enones in
situ and subsequent oxidative arylation with arylboronic acids using relayed
Pd(II) catalysis in one pot under base-free conditions in the presence of oxygen
as efficient and green oxidant.
R. R. Polimera, A. Ilangovan, M. A. M. Subbaiah, J. Org. Chem., 2023, 88,
7256-7271.
Pd-catalyzed Suzuki-Miyaura and Sonogashira cross-coupling reactions of
phosphonium salt-activated, cyclic 1,3-diones provide β-substituted cyclic
enones in good isolated yield and high generality with respect to both
substrates and coupling partners.
S.-M. Yang, G.-H. Kuo, M. D. Gaul, W. V. Murray, J. Org. Chem.,
2016,
81, 3464-3469.
Olefin substrates can be converted to the corresponding enones or 1,4-enediones
in very good yields in short reaction times using a Cu(II) 2-quinoxalinol salen
complex as the catalyst and tert-butyl hydroperoxide (TBHP) as the
oxidant via allylic activation. The reaction tolerates many additional
functional groups.
Y. Li, T. B. Lee, T. Tang, A. V. Gamble, A. E. V. Gorden, J. Org. Chem., 2012,
77, 4628-4633.
Brřnsted acid-mediated cyclizations of siloxyalkynes with simple arenes and
alkenes afforded substituted tetralone and cyclohexenone derivatives. A wide
range of substrates can be employed in these carbocyclizations.
L. Zhang, S. A. Kozmin, J. Am. Chem. Soc., 2004, 126,
10204-10205.
A palladium-catalyzed oxidative cross-coupling of vinyl boronic acids and cyclic
α-diazocarbonyl compounds enables an efficient synthesis of 1,3-diene compounds.
Mechanistically, the reaction involves migratory insertion of palladium carbene
as the key step.
Y. Xia, Y. Xia, Z. Liu, Y. Zhang, J. Wang, J. Org. Chem., 2014,
79, 7711-7717.
Chiral BINOL-derived Brřnsted acids catalyze a highly enantioselective
asymmetric Morita-Baylis-Hillman (MBH) reaction of cyclohexenone with aldehydes.
The reaction requires 2-20 mol% of the chiral Brřnsted acid and
triethylphosphine as the nucleophilic promoter.
N. T. McDougal, S. E. Schaus, J. Am. Chem. Soc., 2003, 125, 12094-12095.
A mild, palladium-catalyzed intramolecular oxidative alkylation of various
ζ-alkenyl β-diketones and ζ-alkenyl β-keto esters in the presence of CuCl2
at room temperature formed the corresponding 2-cyclohexenones in high yield.
T. Pei, X. Wang, R. A. Widenhoefer, J. Am. Chem. Soc., 2003,
125, 648-649.
A solvent-free ytterbium(III) triflate promoted, zinc(II) chloride catalyzed
Conia-ene reaction allows the construction of cyclic enones. In the presence of
zinc(II) chloride and ytterbium(III) triflate, a variety of linear β-alkynic
β-keto esters and β-diketones were cyclized under neat conditions in good yields.
The selectivity toward five- or six-membered-ring carbocycles depends on
substituents at the terminal alkynes.
Y. Liu, R.-J. Song, J.-H. Li, Synthesis, 2010, 3663-3669.
Y. Liu, R.-J. Song, J.-H. Li, Synthesis, 2010, 3663-3669.
A highly stereoselective tandem Michael addition-Wittig reaction of
(3-carboxy-2-oxopropylidene)triphenylphosphorane and α,β-unsaturated aldehydes
gives multifunctional 6-carboxycyclohex-2-en-1-ones in excellent diastereo- and
enantioselectivities by employing the combined catalysis of a bulky chiral
secondary amine, LiClO4, and DABCO.
Y.-k. Liu, C. Ma, K. Jian, T.-Y. Liu, Y.-C. Chen, Org. Lett., 2009,
11, 2848-2851.
An efficient and regioselective Yb(OTf)3-promoted palladium-catalyzed
oxidative cyclization of γ-heteroalkenyl β-keto amides has been developed. Under
simple aerobic condition, various six-, seven-, and eight-membered-ring N-
and O-heterocycles were obtained in excellent yield.
K.-T. Yip, J.-H. Li, O.-Y. Lee, D. Yang, Org. Lett., 2005, 7,
5717-5719.
A simple chiral primary amine catalyses a highly efficient reaction for the
synthesis of both Wieland-Miescher ketone and Hajos-Parrish ketone as well as
their analogues in high enantioselectivity and excellent yields. This procedure
represents one of the most efficient methods for the synthesis of these
versatile chiral building blocks even in gram scale with 1 mol% catalyst loading.
P. Zhou, L. Zhang, S. Luo, J.-P. Cheng, J. Org. Chem., 2012,
77, 2526-2530.
[Cp*RhCl2]2 is a very effective catalyst for C-C
coupling of quinones with aryl and alkyl boronic acids under mild conditions. This reaction provides a practical, efficient method
for the synthesis of aryl- and alkylquinones in good yields at room temperature
and under base-free conditions.
D. Wang, B. Ge, L. Du, H. Miao, Y. Ding,
Synlett, 2014, 25, 2895-2898.
The use of blue light-emitting diodes (LEDs) enables a direct
functionalization of numerous 1,4-quinones with various aryl boronic acids at
room temperature in an open flask without any catalysts and base in
acetonitrile. With diverse 1,4-quinones like 1,4-benzo-, naphtho-, anthra-, and
4-bromonaphthoquinones, facile cross coupling reactions occur with aryl and
alkyl boronic acids.
S. Guha, T. Prakabar, S. Sen, J. Org. Chem., 2022, 87,
15421-15434.
A scalable, direct functionalization of various quinones with several boronic
acids proceeds readily at room temperature in an open flask using catalytic
silver(I) nitrate in the presence of a persulfate co-oxidant. The scope with
respect to quinones is broad, with a variety of alkyl- and arylboronic acids
undergoing efficient cross-coupling.
Y. Fujiwara, V. Domingo, I. B. Seiple, R. Gianatassio, M. Del Bel, P. P. S.
Baran, J. Am. Chem. Soc., 2011,
133, 3292-3295.