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Synthesis of epoxides
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2,2,2-trifluoroacetophenone is an efficient organocatalyst for a cheap,
mild, fast, and environmentally friendly epoxidation of alkenes. Various olefins,
mono-, di-, and trisubstituted, are epoxidized chemoselectively in high to
quantitative yields utilizing low catalyst loadings and H2O2
as a green oxidant.
D. Limniois, C. G. Kokotos, J. Org. Chem., 2014,
79, 4270-4276.
Trifluoroacetone catalyzes a mild and operationally simple epoxidation of
various alkens in good yields using hydrogen peroxide as primary oxidant at high
pH. The use of H2O2 as oxidant significantly reduces the
amount of solvent and salts introduced.
L. Shu, Y. Shi, J. Org. Chem., 2000,
65, 8807-8810.
An effective epoxidation of lipophilic alkenes using hydrogen peroxide was
accomplished with a manganese sulfate/bicarbonate catalytic system in an ionic
liquid at room temperature.
K.-H. Tong, K.-Y. Wong, T. H. Chan, Org. Lett., 2003, 5,
3423-3425.
Methyltrioxorhenium (MTO) catalyzes an epoxidation of alkenes with 30%
aqueous hydrogen peroxide. The addition of 1-10 mol % of 3-cyanopyridine
increases the system's efficiency resulting in high isolated yields of the
corresponding epoxides. Alkenes yielding epoxides more sensitive to nucleophilic
ring opening require a mixture of 3-cyanopyridine and pyridine.
H. Adolfsson, C. Copéret, J. P. Chiang, A. K. Yudin, J. Org. Chem., 2000,
65, 8651-8658.
Organometallic rhenium species (e.g., CH3ReO3) can be
replaced by less expensive inorganic rhenium oxides (e.g., Re2O7,
ReO3(OH), and ReO3) using bis(trimethylsilyl) peroxide (BTSP)
as oxidant in place of aqueous H2O2. Using a catalytic
amount of a proton source, controlled release of hydrogen peroxide helps
preserve sensitive peroxorhenium species and enables catalytic turnover to take
place.
A. K. Yudin, J. P. Chiang, H. Adolfsson, C. Copéret, J. Org. Chem., 2000,
65, 4713-4718.
In MTO-catalyzed epoxidation, aqueous hydrogen peroxide is typically added
dropwise to a dichloromethane solution of the olefin, pyrazole as accelerant,
and MTO. The use of sodium percarbonate (SPC) offers a slow
release of hydrogen peroxide, that can be accelerated using trifluoroacetic acid.
A. R. Vaino, J. Org. Chem., 2000,
65, 4210-4212.
The complex [MnII(R,R-mcp)(CF3SO3)2]
is a very efficient and practical catalyst for the epoxidation of a wide
scope of olefins including terminal, tertiary, cis and trans
internal, enones, and methacrylates using peracetic acid as the terminal
oxidant.
A. Murphy, G. Dubois, T. D. P. Stack, J. Am. Chem. Soc., 2003,
125, 5250-5251.
A bench-stable, solid triazine-based oxidizing reagent,
2-hydroperoxy-4,6-diphenyl-1,3,5-triazine (Triazox) can be synthesized from
inexpensive starting materials. This reagents has been used for epoxidation of
alkenes possessing acid-sensitive functionalities in good to excellent yields.
The accompanying nonacidic triazinone coproduct can be easily removed by
filtration.
K. Yamada, Y. Igarashi, T. Betuyaku, M. Kitamura, K. Hirata, K. Hioki, M.
Kunishima, Org. Lett.,
2018, 20, 2015-2019.
An in situ generated catalyst system based on Mn(CF3SO3)2,
picolinic acid, and peracetic acid converts a broad scope of olefins to epoxides
at 0 °C in <5 min. The reaction offers remarkable oxidant efficiency.
R. A. Moretti, J. Du Bois, T. D. P. Stack, Org. Lett.,
2016, 18, 2528-2531.
Bubbling SO2F2 gas into a solution of olefin, 30%
aqueous hydrogen peroxide, and 2 M aqueous potassium carbonate in 1,4-dioxane at
room temperature for 1 h provides the corresponding epoxides in good to
excellent yields. This inexpensive, mild, and highly efficient epoxidizing
system is suitable to a variety of olefinic substrates including electron-rich
and electron-deficient ones.
C. Ai, F. Zhu, Y. Wang, Z. Yan, S. Lin, J. Org. Chem., 2019, 84,
11928-11934.
An efficient epoxidation of a broad range of olefins using hydrogen peroxide as the oxidant has been accomplished
in the presence of acetic acid and a manganese catalyst that exhibits an uncommon chemoselectivity.
I. Garcia-Bosch, X. Ribas, M. Costas, Adv. Synth. Catal., 2008,
351, 348-352.
A manganese catalyst containing a tetradentate ligand derived from
triazacyclononane exhibits high catalytic activity in epoxidation reactions
using peracetic acid as oxidant. The system exhibits broad substrate scope and
is remarkably selective toward aliphatic cis-olefins. Mechanistic studies
point toward an electrophilic oxidant delivering the oxygen atom in a concerted
step.
I. Garcia-Bosch, A. Company, X. Fontrodona, X. Ribas, M. Costas, Org. Lett., 2008,
10, 2095-2098.
A non-heme iron complex catalyzes highly enantioselective epoxidation of olefins
with H2O2 in the presence of catalytic amounts of
carboxylic acid additives. Ligand and carboxylic acid synergistically cooperate
in promoting efficient O-O cleavage and creating highly chemo- and
enantioselective epoxidizing species which provide a broad range of epoxides in
synthetically valuable yields and short reaction times.
O. Cussó, I. Garcia-Bosch, X. Ribas, J. Lloret-Fillol, M. Costas, J. Am. Chem. Soc., 2013,
135, 14871-14878.
An epoxidation of alkenes using hydrogen peroxide as the terminal
oxidant is promoted by catalytic amounts (1.0-0.1 mol %) of manganese(2+) salts,
and must be performed using at least catalytic amounts of bicarbonate buffer.
Various aryl-substituted, cyclic,
and trialkyl-substituted alkenes were epoxidized under these conditions using 10
equiv of hydrogen peroxide, but monoalkyl-alkenes were not. Additives such as
sodium acetate and salicylic acid enhanced
the rate of the desired epoxidation reaction by 2-3 times. Possible mechanisms for the reaction are discussed.
B. S. Lane, M. Vogt, V. J. DeRosa, K. Burgess, J. Am. Chem. Soc., 2002,
124, 11946-11954.
Enantioselective epoxidations of alkenes were achieved using a Shi-type
carbohydrate-derived hydrate and Oxone. The chiral platform provided by the
catalyst tolerates a wide range of substituents providing high yields and
enantioselectivities. However, styrene derivatives were only converted with poor
selectivities.
N. Nieto, I. J. Munslow, H. Fernández-Pérez, A. Vidal-Ferran, Synlett, 2008,
2856-2858.
Aryl benzyl selenoxides are efficient catalysts for the epoxidation of various
olefinic substrates and the Baeyer-Villiger oxidation of aldehydes and ketones
with hydrogen peroxide.
M. A. Goodman, M. R. Detty, Synlett,
2006, 1100-1104.
A tungsten-bishydroxamic acid complex promotes a simple, efficient, and
environmentally friendly asymmetric epoxidation of allylic, and homoallylic
alcohols at room temperature using aqueous hydrogen peroxide as oxidant.
C. Wang, H. Yamamoto, J. Am. Chem. Soc., 2014,
136, 1222-1225.
A new catalytic system for the asymmetric epoxidation of allylic alcohols
has been developed featuring high enantioselectivity for Z olefins,
catalyst loading of less than 1 mol%, reaction temperatures of 0°C to room
temperature over a shorter time, use of aqueous tert-butyl
hydroperoxide (TBHP) instead of anhydrous TBHP as an achiral oxidant, and
simple workup procedures for small expoxy alcohols.
W. Zhang, A. Basak, Y. Kosugi, Y. Hoshino, H. Yamamoto, Angew. Chem. Int. Ed.,
2005,
44, 4389-4391.
Chiral amino acid-based hydroxamic acids can be effective asymmetric catalysts
for the epoxidation of allylic alcohols, especially disubstituted allylic
alcohols. The mild reaction conditions, e.g., reasonable temperature, low degree
of catalyst loading, and halogen-free solvent, extend the scope of this process.
Y. Hoshino, H. Yamamoto, J. Am. Chem. Soc., 2000,
122, 10452-10453.
Homoallylic alcohols were efficiently epoxidized to the corresponding 3,4-epoxy
alcohols in excellent yields in the presence of methyltrioxorhenium (MTO) as
catalyst, aqueous hydrogen peroxide as the terminal oxidant, and
3-methylpyrazole as an additive. Organic solvent-free conditions accelerate the
reaction.
S. Yamazaki, J. Org. Chem., 2012,
77, 9884-9888.
Chiral bishydroxamic acid ligands provided good yields and high
enantioselectivities in the vanadium-catalyzed asymmetric epoxidation of
homoallylic alcohols.
W. Zhang, H. Yamamoto, J. Am. Chem. Soc., 2007,
129, 286-287.
Use of a solvent with greater density than the fluorous phase is an
alternative to the U-tube method in phase-vanishing reactions in cases where
both reactants are less dense than the fluorous phase.
N. K. Jana, J. G. Verkade, Org. Lett., 2003, 5,
3787-3790.
N. K. Jana, J. G. Verkade, Org. Lett., 2003, 5,
3787-3790.
A highly chemo- and enantioselective epoxidation of conjugated cis-enynes
using readily available glucose-derived ketones as catalysts and Oxone as
oxidant forms cis-propargyl epoxides in high ee's. The interaction
between the alkyne substrate and the oxazolidinone moiety of the ketone catalyst
are important for the stereodifferentiation.
C. P. Burke, Y. Shi, J. Org. Chem., 2007,
72, 4093-4097.
Highly enantio- and diastereoselective one-pot procedures for the synthesis
of epoxy alcohols involve either asymmetric addition of an alkylzinc reagent
to an enal or asymmetric vinylation of an aldehyde with divinylzinc
reagents. Exposure of the reaction mixtures to dioxygen and addition of
catalytic titanium tetraisopropoxide yields epoxy alcohols with good to
excellent yields.
A. E. Lurain, A. Maestri, A. R. Kelli, P. J. Carroll, P. J. Walsh, J. Am. Chem. Soc.,
2004,
126, 13608-13609.
A. E. Lurain, A. Maestri, A. R. Kelli, P. J. Carroll, P. J. Walsh, J. Am. Chem. Soc.,
2004,
126, 13608-13609.
A series of 20 chiral epoxides were obtained with excellent yields and
enantioselectivities within short reaction times using hybrid amide-based
Cinchona alkaloids as catalysts at very low loading. Moreover, the catalyst
solution can be reused 10times, without further catalyst addition to the
reaction mixture.
M. Majdecki, A. Tyszka-Gumkowska, J. Jurczak,
Org. Lett., 2020, 22, 8687-8691.
A simple and efficient enantioselective epoxidation of α,β-unsaturated ketones
is catalyzed by rare-earth metal amides in the presence of
phenoxy-functionalized chiral prolinols at room temperature using tert-butylhydroperoxide
(TBHP) as the oxidant. The combination of an Yb-based amide and a chiral
proligand provided chiral epoxides in excellent yields and enantiomeric excess
of up to 99%.
C. Zeng, D. Yuan, B. Zhao, Y. Yao, Org. Lett.,
2015,
17, 2242-2245.
An aerobic photoepoxidation of α,β-unsaturated ketones is driven by visible
light in the presence of tetramethylguanidine (TMG), tetraphenylporphine (H2TPP),
and molecular oxygen under mild conditions to provide α,β-epoxy ketones in good
yields in 96 h. The reaction time can be shortened to 5 h using flow synthesis.
Y. Wu, G. Zhou, Q. Meng, X. Tang, G. Liu, H. Yin, J. Zhao, F. Yang, Z. Yu, Y.
Luo, J. Org. Chem., 2018, 83,
13051-13062.
A chiral N,N'-dioxide/ScIII complex catalyzes an enantioselective
epoxidation of α-substituted vinyl ketones in the presence of H2O2
as the oxidant to provide key epoxide intermediates for the synthesis of various
triazole antifungal agents. The reaction proceeded efficiently in high yields
and with good enantioselectivities.
Q. He, D. Zhang, F. Zhang, X. Liu, X. Feng, Org. Lett., 2021, 23,
6795-6800.
Using cinchona alkaloid-derived primary amines as catalysts and aqueous hydrogen
peroxide as the oxidant, highly enantioselective Weitz-Scheffer-type epoxidation
and hydroperoxidation reactions of α,β-unsaturated carbonyl compounds take place.
Acyclic enones, cyclic enones, and α-branched enals can be converted.
Intermediates have been characterized by MS and NMR. DFT calculations explain
the activation of H2O2.
O. Lifchits, M. Mahlau, C. M. Reisinger, A. Lee, C. Farès, I. Polyak, G.
Gopakumar, W. Thiel, B. List, J. Am. Chem. Soc., 2013,
135, 6677-6693.
Using cinchona alkaloid-derived primary amines as catalysts and aqueous hydrogen
peroxide as the oxidant, highly enantioselective Weitz-Scheffer-type epoxidation
and hydroperoxidation reactions of α,β-unsaturated carbonyl compounds take place.
Acyclic enones, cyclic enones, and α-branched enals can be converted.
Intermediates have been characterized by MS and NMR. DFT calculations explain
the activation of H2O2.
O. Lifchits, M. Mahlau, C. M. Reisinger, A. Lee, C. Farès, I. Polyak, G.
Gopakumar, W. Thiel, B. List, J. Am. Chem. Soc., 2013,
135, 6677-6693.
Heterobimetallic complexes stabilized by chiral phenoxy-functionalized
prolinolate are highly active in catalyzing the epoxidation of α,β-unsaturated
ketones, while the enantioselectivity varies according to the ionic radii of the
rare earth center. A series of chalcone derivatives were converted to chiral
epoxides in good ee at 0°C using TBHP as the oxidant.
Q. Qian, Y. Tan, B. Zhao, T. Feng, Q. Shen, Y. Yao, Org. Lett.,
2014,
16, 4516-4519.
Visible-light-driven hydroacylations and epoxyacylations in water using
methylene blue as photoredox catalyst and persulfate as oxidant deliver ketones
and epoxyketones from a range of aromatic and aliphatic aldehydes as well as
conjugated and nonconjugated olefins as abundant and inexpensive chemical
feedstocks.
G. F. P. de Souza, J. A. Bonacin, A. G. Salles, Jr., J. Org. Chem., 2018, 83,
8331-8340.
Under the synergistic actions of photocatalyst Ru(bpy)3Cl2,
tert-butyl hydroperoxide, cesium carbonate, and visible light irradiation,
a range of styrenes and benzaldehydes smoothly form α,β-epoxy ketones via
visible-light-enabled photocatalytic generation of acyl radicals as key
intermediates.
J. Li, D. Z. Wang, Org. Lett.,
2015,
17, 5260-5263.
A CuII-catalyzed oxidative C-C/O-C homocoupling/cyclization
strategy of phenacyl bromides provides α,β-ketoepoxides with high yield and
cis-selectivity. The homocoupling method was extended to cross-coupling
between phenacyl bromides with benzyl bromides.
D. Ghosh, S. A. Molla, N. N. Ghosh, S. Khamarui, D. K. Maiti, J. Org. Chem., 2023, 88,
9657-9667.
Chiral primary amine salts catalyze highly enantioselective epoxidations of
cyclic enones with hydrogen peroxide.
X. Wang, C. M. Reisinger, B. List, J. Am. Chem. Soc., 2008,
130, 6070-6071.
An asymmetric 1,2-addition of alkyl groups to conjugated cyclic enones gave allylic alcohols with chiral quaternary centers. The resultant
allylic alcohols are converted into epoxy alcohols with excellent
diastereoselectivities. A semipinacol rearrangement provided α,α-dialkyl-β-hydroxy
ketones with all-carbon chiral quaternary centers.
S.-J. Jeon, P. J. Walsh, J. Am. Chem. Soc., 2003,
125, 9544-9545.
The catalytic asymmetric addition of alkyl groups to ketones under highly
concentrated and solvent-free conditions permits reduction in catalyst loading
by a factor of 2- to 40-fold compared with standard reaction conditions
employing toluene and hexanes. Using cyclic conjugated enones, solvent-free
asymmetric addition followed by a diastereoselective epoxidation using 5.5 M
decane solution of tert-butyl hydroperoxide generated epoxy alcohols.
S.-J. Jeon, H. Li, P. J. Walsh, J. Am. Chem. Soc.,
2005,
127, 16416-16425.
A chiral bisaryl-silyl-protected pyrrolidine acts as a very selective
epoxidation organocatalyst using simple oxidation agents. The scope of the
reaction is demonstrated by the formation of optically active α,β-epoxy
aldehydes in high yields and enantioselectivities. The asymmetric
epoxidation reactions proceed also under environmental friendly reaction
conditions in, for example, water mixtures of alcohols.
M. Marigo, J. Franzen, T. B. Poulsen, W. Zhuang, K. A. Jorgensen, J. Am. Chem. Soc.,
2005,
127, 6284-6289.
A catalytic asymmetric epoxidation reaction of various α,β-unsaturated
esters via a conjugate addition of an oxidant using an yttirium-chiral
biphenyldiol catalyst yielded the corresponding α,β-epoxy esters in up to
97% yield and 99% ee.
H. Kakei, R. Tsuji, T. Ohshima, M. Shibasaki, J. Am. Chem. Soc.,
2005,
127, 8962-8963.
Promising, dual-functioning chiral catalysts for the highly enantioselective
epoxidation of α,β-unsaturated ketones gave epoxy chalcones in excelllent
yield and high enantioselectivity using 13% NaOCl as oxidizing agent in
toluene under mild phase-transfer conditions.
T. Ooi, D. Ohara, M. Tamura, K. Maruoka, J. Am. Chem. Soc.,
2004,
126, 6844-6845.
A highly enantioselective catalytic epoxidation of α,β-unsaturated diaryl enones
was achieved with high chemical yield by using aqueous hydrogen peroxide in the
presence of a guanidine-urea bifunctional organocatalyst. The catalyst performs
cooperatively by interaction of the guanidine group with hydrogen peroxide and
the urea group with the enone or vice versa.
S. Tanaka, K. Nagasawa Synlett, 2009,
667-670.
The epoxidation of trans-chalcones proceeds under mild conditions at room
temperature in alkaline solution to afford the corresponding epoxides in
excellent yields using trans-3,5-dihydroperoxy-3,5-dimethyl-1,2-dioxolane
as an efficient oxygen source.
D. Azarifar, K. Khosravi, Synlett, 2010,
2755-2758.
A new and efficient chiral catalyst system, lanthanum-chiral BINOL-tris(4-fluorophenyl)phosphine
oxide-cumene hydroperoxide, was developed for the epoxidation of
α,β-unsaturated ketones, thus providing the corresponding epoxy ketones with
excellent enantioselectivities (up to >99% ee) in good to excellent yields
at room temperature.
R. Kino, K. Daikai, T. Kawanami, H. Furuno, J. Inanaga, Org. Biomol.
Chem., 2004, 2, 1822-1824.
1-Trifluoroboratoalkenes are oxidized by dioxirane, providing air-stable,
crystalline oxiranyltrifluoroborates without cleavage of the carbon-boron
bond. The first Suzuki-Miyaura coupling of an epoxytrifluoroborate has been
accomplished.
G. A. Molander, M. Ribagorda, J. Am. Chem. Soc., 2003,
125, 11148-11149.