Categories: C-C Bond Formation > Cyclic compounds > Cyclic enones
Synthesis of cyclopentenones
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Recent Literature
Cyclization of electron-rich 2-alkyl-1-ethynylbenzene derivatives was catalyzed
by TpRuPPh3(CH3CN)2PF6 in hot
toluene to form 1-substituted-1H-indene and 1-indanone products. The
cyclization mechanism involves a 1,5-hydrogen shift of an initial
metal-vinylidene intermediate.
A. Odedra, S. Datta, R.-S. Liu, J. Org. Chem., 2007,
72, 3289-3292.
A nickel-catalyzed enal-alkyne cycloaddition directly affords cyclopentenols,
whereas an enoate-alkyne cycloaddition affords the analogous cyclopentenones.
The mechanism of these processes likely involves formation and protonation of a
metallacyclic intermediate. The general strategy provides a straightforward
entry to five-membered ring products from simple, stable π-systems.
A. D. Jenkins, A. Herath, M. Song, J. Montgomery, J. Am. Chem. Soc., 2011,
133, 14460-14466.
A highly efficient catalytic, intermolecular synthesis of the cyclopentane
skeleton from simple starting products is reported. Allyl halides, alkynes, and
carbon monoxide react under very mild reaction conditions by means of a
substoichiometric amount of iron, acetone, and a catalytic amount of Ni(II)
iodide.
M. L. Nadal, J. Bosch, J. M. Vila, G. Klein, S. Ricart, J. M. Moretó, J. Am.
Chem. Soc., 2005, 127, 10476-10477.
Indanones and 2-cyclopentenones have been successfully prepared in good to
excellent yields by the palladium-catalyzed carbonylative cyclization of
unsaturated aryl iodides and dienyl triflates, iodides, and bromides,
respectively. The mechanism is discussed.
S. V. Gagnier, R. C. Larock, J. Am. Chem. Soc., 2003, 125,
4804-4807.
Conjugated addition of primary nitroalkanes to α,β-unsaturated ketones or
α,β-unsaturated esters, in the presence of two equivalents of DBU, allows the
one-pot prepration of γ-diketones or γ-keto esters, respectively. The reaction
of 2-aryl-1-nitroethane derivatives with α,β-unsaturated ketones gives
cyclopentenones.
R. Ballini, L . Barboni, G. Bosica, D. Fiorini, Synthesis, 2002,
2725-2728.
An intramolecular Friedel-Crafts-type cyclization of vinyl chlorides and
subsequent Pd-catalyzed cross-coupling reactions allow the synthesis of
3,5-diarylcyclopentenones. The requisite vinyl chloride-bearing arylacetic acid
precursors are readily available by straightforward alkylation of arylacetic
acid esters.
Y. Xu, M. McLaughlin, C.-y. Chen, R. A. Reamer, P. G. Dormer, I. W. Davies, J. Org. Chem., 2009,
74, 5100-5103.
Y. Xu, M. McLaughlin, C.-y. Chen, R. A. Reamer, P. G. Dormer, I. W. Davies, J. Org. Chem., 2009,
74, 5100-5103.
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.
The Au-catalyzed hydrative rearrangement of 1,1-diethynylcarbinol acetates in
wet CH2Cl2 produces either
5-acetoxy-2-alkyl-2-cyclopentenones or acetoxymethyl α-alkylallenones as a major
product depending on the temperature, reaction time, and catalyst loading.
C. H. Oh, S. Karmakar, J. Org. Chem., 2009,
74, 370-374.
Synthesis of 5-Hydroxycyclopent-2-enones from Allenyl Vinyl Ketones via an
Interrupted Nazarov Cyclization
V. M. Marx, D. J. Burnell, Org. Lett., 2009,
11, 1229-1231.
Treatment of an allenyl vinyl ketone with trifluoroacetic acid leads to Nazarov
cyclization, in which the intermediate carbocation is trapped efficiently by
trifluoroacetate. Hydrolysis of the ester with methanol and basic alumina
provides a trans-disubstituted 5-hydroxycyclopent-2-enone in very good
yields.
E. A. Uhrich, W. A. Batson, M. A. Tius, Synthesis, 2006,
2139-2142.
A planar chiral DMAP catalyst efficiently promotes asymmetric Morita-Baylis-Hillman reactions
of cyclopentenone with various aldehydes in the presence of MgI2 as
cocatalyst.
A. Bugarin, B. T. Connell, Chem. Commun., 2010,
46, 2644-2646.
The acid-catalyzed Nazarov reaction of easily accessible β-alkoxy divinyl
ketones provides 5-oxycyclopent-2-enones. The effects of the β-alkoxy group on
the catalyst efficiency and the regioselectivity are based on the stabilization
of the intermediates and the spontaneous elimination of the group followed by
trapping.
M. Shindo, K. Yaji, T. Kita, K. Shishido, Synlett, 2007,
1096-1100.
A chiral iridium diphosphine complex catalyzes an enantioselective
intramolecular Pauson-Khand-type reaction to give various chiral bicyclic
cyclopentenones. A low partial pressure of carbon monoxide is important to
achieve excellent enantioselectivity.
T. Shibata, N. Toshida, M. Yamasaki, S. Maekawa, K. Takagi, Tetrahedron,
2005, 61, 9974-9979.
The Rh(I)-catalyzed [3 + 2] cycloaddition of cyclopropenones and alkynes
provides a highly efficient and regioselective route to cyclopentadienones (CPDs)
that would be otherwise difficult to obtain. The versatility of the method is
explored with a wide range of alkynes and diaryl- as well as
arylalkylcyclopropenones.
P. A. Wender, T. J. Paxton, T. J. Williams, J. Am. Chem. Soc., 2006,
128, 14814-14815.
An entrapped Rh catalyst derived by a sol-gel process (see article for method),
has been used in a Pauson-Khand reaction under mild conditions. The catalyst can
be reused at least 10 times without losing activity. This catalytic system is
not effective for intermolecular reactions.
K. H. Park, S. U. Song, Y. K. Chung, Tetrahedron Lett., 2003,
44, 2827-2830.
