Categories: C-O Bond Formation >
Synthesis of ethers
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Reductive Etherification
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Recent Literature
Nucleophilic fluorination using CsF or alkali metal fluorides was completed in
short reaction time in the presence of [bmim][BF4] affording the
desired products without any byproducts. Facile nucleophilic substitutions such
as halogenations, acetoxylation, nitrilation, and alkoxylations in the presence
of ionic liquids provided the desired products in good yields.
D. W. Kim, C. E. Song, D. Y. Chi, J. Org. Chem., 2003, 68,
4281-4285.
A novel electrolytic system for non-Kolbe electrolysis based on the acid-base
reaction between carboxylic acids and solid-supported bases in MeOH provide the
corresponding methoxylated products in excellent yields. The acid-base reaction
between carboxylic acids and solid-supported bases preferentially takes place to
reduce the cell voltage in MeOH.
T. Tajima, H. Kurihara, T. Fuchigami, J. Am. Chem. Soc., 2007,
129, 6680-6681.
An efficient method chemoselectively converts benzyl alcohols into their methyl
or ethyl ethers in the presence of aliphatic or phenolic hydroxyl groups using
2,4,6-trichloro-1,3,5-triazine (TCT) and dimethyl sulfoxide in methanol or
ethanol.
L. Sun, Y. Guo, G. Peng, C. Li, Synthesis, 2008,
3487-3488.
A Zn(OTf)2-catalyzed coupling of alcohols/phenols with unactivated
tertiary alkyl bromides and a Cu(OTf)2-catalyzed thiolation of unactivated
tertiary alkyl oxalates with thiols provide sterically hindered tertiary alkyl
ethers and thioethers.
Y. Gong, Z. Zhu, Q. Qian, W. Zong, H. Gong, Org. Lett., 2021, 23,
1005-1010.
A sulfoxonium metathesis reaction between TMSOI and
cost-effective DMSO-d6 provides deuterated trimethylsulfoxonium
iodide (TDMSOI). Subsequent "one-pot" trideuteromethylation installs the -CD3 moiety into broad functionalities including phenols,
thiophenols, acidic amines, and enolizable methylene units in high yield and at
a useful level of deuteration.
Z. Shen, S. Zhang, H. Geng, J. Wang, X. Zhang, A. Zhou, C. Yao, X. Chen, W.
Wang, Org. Lett.,
2019, 21, 448-452.
N-Trifluoromethoxyphthalimide (PhthN-OCF3) is a stable and
solid trifluoromethoxylating reagent, that releases an OCF3 anion
under mild reaction conditions. PhthN-OCF3 can be used for the
nucleophilic trifluoromethoxylation of various alkyl electrophiles to provide
trifluoromethyl ethers with unique properties in good yields.
W.-J. Yuan, C.-L. Tong, X.-H. Xu, F.-L. Qing, J. Org. Chem., 2023, 88,
4434-4441.
A new synthetic method for the preparation of potassium
organotrifluoroborates through nucleophilic substitution of potassium bromo-
and iodomethyltrifluoroborates is described. Potassium
halomethyltrifluoroborates have been prepared via in situ reaction of n-BuLi
with dibromo- and diiodomethane, respectively, in the presence of trialkyl
borates, followed by treatment with KHF2.
G. A. Molander, J. Ham, Org. Lett.,
2006,
8, 2031-2034.
An oxa-Matteson reaction enables sequential oxygen and carbenoid insertions
into diverse alkyl- and arylboronates to provide a wide range of
boron-substituted ethers. The utilities of this method are demonstrated in the
the asymmetric synthesis of an acetyl-CoA-carboxylase inhibitor, and the
programmable construction of polyethers.
Q. Xi, G. Dong, J. Am. Chem. Soc.,
2022, 144, 8498-8503.
A gold-catalyzed, microwave protocol activates alcohols through an
intermolecular, SN1-type reaction to directly form unsymmetrical
ethers and Cbz-protected amines in good yields. This reaction is highly
reproducible and tolerates moisture.
A. R. S. Vinson, V. K. Davis, A. Arunasalam, K. A. Jesse, R. E. Hamilton, M. A.
Shattuck, A. C. Hu, R. G. Iafe, A. G. Wenzel,
Synlett, 2015, 26, 765-770.
An efficient intermolecular conjugate addition of various primary and secondary
alcohols to unsaturated ketones and esters is catalyzed by the free carbene
derived from IMes·HCl. No oligomerization is observed under these mild
conditions. In addition to reactions with activated alkenes, IMes catalyzes the
formation of vinyl ethers through the 1,4-addition of alcohols to ynones.
E. M. Phillips, M. Riedrich, K. A. Scheidt, J. Am. Chem. Soc., 2010,
132, 13179-13181.
The combination of a copper-catalyzed C-O coupling reaction with a
subsequent Claisen rearrangement allowed the generation of two adjacent
quarternary stereocenters in a one-pot domino process. Furthermore, an
experimentally simple stereoselective synthesis of of vinyl ethers is
delineated using the same catalyst system.
G. Nordmann, S. L. Buchwald, J. Am. Chem. Soc., 2003,
125, 4978-4979.
The use of a (P,N) ligand enables a highly regioselective Ni-catalyzed
hydroalkoxylation of 1,3-dienes. The optimized protocol operates under
particularly mild conditions, provides access to a broad range of structurally
diverse allylic ethers, and tolerates a number of sensitive functional groups.
G. Tran, C. Mazet,
Org. Lett., 2019, 21, 9060-9065.
A Pd[BiPhePhos] catalyst enables the use nonactivated phenols as nucleophiles in
the allylation of nonderivatized allylic alcohols to generate allylated phenolic
ethers in very good yields with water as the only byproduct. The kinetically
favored O-allylated products are formed exclusively over the thermodynamically
favored C-allylated products.
T. Rukkijakan, S. Akkarasamiyo, S. Sawadjoon, J. S. M. Samec, J. Org. Chem., 2018, 83,
4099-4104.
A stereospecific and stereoselective, copper-promoted coupling of vinyl pinacol
boronate esters and alcohols allows the synthesis of enol ethers in very good
yields, is compatible with various functional groups, and occurs at room
temperature. Cupric acetate is the copper source, and triethylamine buffer is
used to prevent protodeboration.
R. E. Shade, A. M. Hyde, J.-C. Olsen, C. A. Merlic, J. Am. Chem. Soc., 2010,
132, 1202-1203.
Using commercially available Ph3PAuCl and readily prepared, benign
arylsilanes, a gold-catalyzed oxyarylation of alkenes proceeds smoothly in air.
The oxidant, Selectfluor, not only facilitates entry to the Au(I/III) manifold
but also provides a fluoride anion for silane activation, thereby avoiding the
need for addition of a stoichiometric base.
L. T. Ball, M. Green G. C. Lloyd-Jones, C. A. Russel, Org. Lett., 2010,
12, 4724-4727.
A microwave-assisted, chemoselective and efficient method for the cleavage of
silyl ethers is catalyzed by Selectfluor. A wide range of TBDMS-, TIPS-, and
TBDPS-protected alkyl silyl ethers can be chemoselectively cleaved in high yield
in the presence of aryl silyl ethers. In addition, the transetherification and
etherification of benzylic hydroxy groups in alcoholic solvents is observed.
S. T. A. Shah, S. Singh, P. J. Guiry, J. Org. Chem., 2009,
74, 2179-2182.
A nickel(0) triethyl phosphite complex promotes the reaction of allylic acetates
with thiols to produce allylic sulfides with retention of configuration without
allylic rearrangement. A similar reaction of allylic acetates with alcohols and
phenols also proceeds with retention of regio- and stereochemistry.
Y. Yatusmonji, Y. Ishida, A. Tsubouchi, T. Takeda, Org. Lett., 2007,
9, 4603-4606.
A wide range of ynol ethers can be prepared via displacement at an sp center.
The same protocol can be applied to the synthesis of synthetically useful
thioynol ethers. This reaction, which generates highly functionalized,
heteroatom-substituted alkynes, involves radical intermediates.
V. J. Gray, J. Cuthbertson, J. D. Wilden, J. Org. Chem., 2014,
79, 5869-5874.
The hydroalkoxylation of allenes with alcohols proceeds smoothly in the presence
of a catalytic amount of Ph3PAuNO3 and H2SO4
to give allylic ethers in good yields and high regio- and stereoselectivity.
D.-M. Cui, K.-R. Yu, C. Zhang, Synlett, 2009,
1103-1106.
A mild method for the trimethylsilyl trifluoromethanesulfonate (TMSOTf)
catalyzed one-pot synthesis of homoallyl ethers from aldehydes has been
developed in the ionic liquid 1-butyl-3-methylimidazolium
trifluoromethanesulfonate ([bmim] [OTf]). The advantages of this method include
the use of a recyclable ionic liquid, facile product isolation without employing
excess organic solvent and elimination of an aqueous waste stream.
P. W. Anzalone, R. S. Mohan,
Synthesis, 2005, 2661-2663.
P. W. Anzalone, R. S. Mohan,
Synthesis, 2005, 2661-2663.
A general, Ir(I)-catalyzed enantioselective decarboxylative allylic
etherification of aryl allyl carbonates provides aryl allyl ethers with high
stereoselection.
D. Kim, S. Reddy, O. V. Singh, J. S. Lee, S. B. Kong, H. Han, Org. Lett., 2013,
15, 512-515.
Chiral phosphine-catalyzed coupling of two readily available partners,
γ-aryl-substituted alkynoates and alcohols, under mild conditions enables the
enantioselective synthesis of benzylic ethers via internal redox reaction of the
alkynoate partner.
D. T. Ziegler, G. C. Fu, J. Am. Chem. Soc., 2016,
138, 12069-12072.
A Pd-catalysed termolecular allenylation cascade followed by a Ru catalysed RCM
process affords a diverse range of Δ3-aryl/heteroaryl substituted
five-seven membered nitrogen and oxygen heterocycles.
H. A. Dondas, B. Clique, B. Cetinkaya, R. Grigg, C. Kilner, J. Morris, V.
Sridharan, Tetrahedron, 2005,
61, 10652-10666.
p-Toluenesulfonic acid efficiently catalyzes direct
nucleophilic substitutions of the hydroxy groups of propargylic alcohols with a
large variety of carbon- and heteroatom-centered nucleophiles. Reactions can be
conducted under mild conditions and in air without the need for dried
solvents.
R. Sanz, A. Martinez, J. M. Alvarez-Gutierrez, F. Rodriquez, Eur. J. Org. Chem., 2006,
1383-1386.
A general and efficient FeCl3-catalyzed substitution reaction of
propargylic alcohols with carbon- and heteroatom-centered nucleophiles such
as allyl trimethylsilane, alcohols, aromatic compounds, thiols, and amides,
forms new C-C, C-O, C-S and C-N bonds.
Z.-P. Zhan, J.-L. Yu, Y.-Y. Cui, R.-F. Yang, W.-Z. Yang, J.-P. Li, J. Org. Chem., 2006,
71, 8298-8301.
An economic and practical transformation from secondary alkyl-substituted
propargyl acetates to a variety of nucleophilic substitution products is
catalyzed by inexpensive InCl3. High yields and excellent
chemoselectivity were obtained. Five-, six-, and seven-membered propargyl
cycloethers were also successfully constructed.
M. Lin, L. Hao, X.-t. Liu, Q.-z. Chen, F. Wu, P. Yan, S.-x. Xu, X.-l. Chen, J.-j.
Wen, Z.-p. Zhan, Synlett, 2011,
665-670.
The preparation of diverse β-chloroethers, β-chloroacetates, and
chlorohydrins is efficiently achieved under mild conditions by reaction of
alkenes with trichloroisocyanuric acid in alcohols, acetic acid or aqueous
acetone, respectively.
G. Fonseca Mendonça, A. Manzolillo Sanseverino, M. C. S. de Mattos, Synthesis,
2003, 45-48.
Electrochemical technology enables alkene alkoxyhalogenation and organohalide
dehalogenation in one pot. Anodic conversion of the C=C bond to radical cation
intermediates and cathodic transformations of organohalides run in parallel.
T.-T. Zhang, M.-J. Luo, Y. Li, R.-J. Song, J.-H. Li,
Org. Lett., 2020, 22, 7230-7233.
A constant current electrolysis synergizing with a Lewis-acid catalysis
protocol enables an external oxidant-free oxytrifluoromethylation and
aminotrifluoromethylation of styrene derivatives using sodium
trifluoromethanesulfinate as the trifluoromethyl source.
L. Zhang, G. Zhang, P. Wang, Y. Li, A. Lei, Org. Lett.,
2018, 20, 7396-7399.
A catalyst- and additive-free, visible-light-induced O-H insertion reaction of
diazo compounds produces valuable α-hydroxy and α-alkoxy esters in good yields.
The protocol exhibits a broad substrate scope and good functional-group
tolerance. Notably, a gram-scale synthesis has been performed in a photochemical
continuous-flow mode.
J. Bai, D. Qi, Z. Song, B. Li, L. Guo, C. Yang, W. Xia, Synlett, 2022,
33,
2048-2052.
A cobalt-catalyzed
α-methoxymethylation of ketones with methanol as a sustainable C1 source,
cheap CoCl2·6H2O as catalyst and TBHP as oxidant provides the methoxymethylated products
within a short reaction time in very good yield. α-Aminomethylated ketones can
be produced by a one-pot methylenation/aza-Michael addition sequence or by a
base-mediated conversion of the α-methoxymethyl ketones.
J. Yang, S. Chen, H. Zhou, C. Wu, B. Ma, J. Xiao, Org. Lett.,
2018, 20, 6774-6779.
Despite the high reactivity of alkoxyl (RO·) radicals and their propensity to
easily undergo β-scission or Hydrogen Atom Transfer (HAT) reactions, an
efficient photoredox-mediated intermolecular trapping of alkoxyl radicals by
silyl enol ethers enables the introduction of both structurally simple and more
complex alkoxy groups into a wide range of ketones and amides.
C. Banoun, F. Bourdreux, E. Magnier, G. Dagousset, Org. Lett., 2021, 23,
8921-8925.
The reaction between ethynylbenziodoxol(on)es (EBXs)
and phenols driven by visible light provides (Z)-2-iodovinyl phenyl ethers
with excellent regio- and stereoselectivity. The (Z)-2-iodovinyl phenyl
ether products can be further stereospecifically functionalized to form
trisubstituted alkenes, demonstrating the potential of these products en route
to chemical complexity.
B. Liu, C.-H. Lim, G. M. Miyake, J. Am. Chem. Soc.,
2018,
140, 12829-12835.