Triethylsilane (TES)
Recent Literature
Primary alcohols and ethers were effectively reduced to the corresponding
hydrocarbons by HSiEt3 in the presence of catalytic amounts of B(C6F5)3.
Secondary alkyl ethers are cleaved under similar reaction conditions to produce
silyl ethers. The following relative reactivity order of substrates was found:
primary >> secondary > tertiary.
V. Gevorgyan, M. Rubin, S. Benson, J.-X. Liu, Y. Yamamoto, J. Org. Chem., 2000,
65, 6179-6168.
An Et3SiH-promoted diastereoselective reductive aldol
reaction has been developed using InBr3 as a catalyst. This
three-component reaction afforded only silyl aldolates as products
without any side reactions.
I. Shibata, H. Kato, T. Ishida, M. Yasuda, A. Baba, Angew. Chem. Int. Ed.,
2004,
43, 711-714.
The combination of molecular iodine and a hydrosilane enables a practical
reduction of N-sulfonyl aldimines to the corresponding N-alkylsulfonamides.
J. Jiang, L. Xiao, Y.-L. Li, J. An, Synlett, 2021,
32,
291-294.
Reductive amination between aldehydes or ketones and amines occurs smoothly
within the hydrophobic cores of nanomicelles in water. A broad range of
substrates can be converted under mild conditions in the presence of 0.20 mol %
Pd/C and triethylsilane, leading to high chemical yields of the desired
secondary and tertiary amines.
R. R. Thakore, B. S. Takale, G. Casotti, E. S. Gao, H. S. Jin, B. H. Lipshutz,
Org. Lett., 2020, 22, 6324-6329.
An efficient methodology for the reductive alkylation of secondary amines
with aldehydes and Et3SiH using an iridium complex as a catalyst
has been developed. In addition, a cheaper, easy-to-handle, and
environmentally friendly reducing reagent such as polymethylhydrosiloxane
(PMHS) in place of Et3SiH was also useful.
T. Mizuta, S. Sakaguchi, Y. Ishii, J. Org. Chem., 2005, 70, 2195-2199.
Reductive amination of aldehydes and ketones with the InCl3/Et3SiH/MeOH
system is highly chemoselective and can be applied to various cyclic, acyclic,
aromatic, and aliphatic amines. Functionalities including ester, hydroxyl,
carboxylic acid, and olefin are tolerated.
O.-Y. Lee, K.-L. Law, C.-Y. Ho, D. Yang, J. Org. Chem., 2008,
73, 8829-8837.
Medium-sized cyclic ethers have been effectively synthesized through
intramolecular reductive coupling of dialdehydes in the presence of a
hydrosilane and low loadings of AgNTf2 as catalyst at 25°C. The
catalytic system is also suitable for the coupling of two different
monoaldehydes to provide unsymmetrical ethers. This protocol features broad
functional group compatibility and high product diversity.
T. Liang, G. Dong, C. Li, X. Xu, Z. Xu, Org. Lett.,
2022, 24, 1817-1821.
A simple iron- and silyl chloride catalyzed reductive etherification enables the
preparation of symmetrical and nonsymmetrical ethers from various aldehydes and
ketones in the presence of triethylsilane as a reducing agent and catalytic
amounts of iron(III) oxo acetate and chloro(trimethyl)silane. The
reactions can be carried out at ambient temperatures in ethyl acetate as the
solvent.
R. Savela, R. Leino,
Synthesis, 2015, 47, 1749-1760.
Facile reductive etherification of carbonyl compounds can be conveniently
performed by reaction with triethylsilane and alkoxytrimethylsilane
catalyzed by iron(III) chloride. The corresponding alkyl ethers, including
benzyl and allyl ethers, of the reduced alcohols were obtained in good to
excellent yields under mild reaction conditions.
K. Iwanami, H. Seo, Y. Tobita, T. Oriyama, Synthesis, 2005, 183-186.
A novel one-pot procedure for a directly reductive conversion of esters to the
corresponding ethers by Et3SiH in the presence of a catalytic amount
of InBr3 is described. This simple catalytic system appeared to be
remarkably tolerant to several functional groups.
N. Sakai, T. Moriya, T. Konakahara, J. Org. Chem., 2007,
72, 5920-5922.
Various silyl ethers were readily and efficiently transformed into the
corresponding alkyl ethers in high yields by the use of aldehydes combined with
triethylsilane in the presence of a catalytic amount of iron(III) chloride.
K. Iwanami, K. Yano, T. Oriyama, Synthesis, 2005, 2669-2672.
Re2(CO)10 efficiently catalyzes the direct reduction of
various carboxylic acids under UV irradiation at ambient temperature. While
aliphatic carboxylic acids were readily converted to the corresponding
disilylacetals with low catalyst loading in the presence of Et3SiH,
aromatic analogues required more drastic conditions.
D. Wei, R. Buhaibeh, Y. Canac, J.-B. Sortais,
Org. Lett., 2019, 21, 7713-7716.
The combination of the tris-4-bromophenylamminium radical cation, commonly
known as magic blue (MB•+), and triethylsilane mediates a mild OtBu
deprotection. Magic blue catalytically facilitates the cleavage of the C-O bond
in tert-butyl carbamates, carbonates, esters, and ethers in a high
isolated yield under mild conditions, and sacrificial triethylsilane accelerates
the reaction.
D. Hidasová, Tomáš Slanina, J. Org. Chem., 2023, 88,
6932-6938.
Air-stable cationic hemiboronic acids catalyze chemoselective reduction of
enones. Depending on the silane reducing agent, either the conjugate reduction
products or the fully reduced products can be obtained in high selectivity.
J. P. G. Rygus, D. B. Boateng, D. G. Hall, Synlett, 2023,
34,
2215-2219.
Treatment of 1,2-O-isopropylidenefuranose derivatives with
triethylsilane/boron trifluoride etherate provides tetrahydrofurans. The removal
of the 1,2-O-isopropylidene group is accompanied by deoxygenation at the
anomeric position. This process is compatible with several hydroxyl protecting
groups.
G. J. Ewing, M. J. Robins,
Org. Lett., 1999, 1, 635-636.
A chemoselective activation of a secondary amide with triflic anhydride in the
presence of 2-fluoropyridine enables a mild reduction using triethylsilane, a
cheap and rather inert reagent. Imines can be isolated after a basic workup or
readily transformed to the aldehydes following an acidic workup. The amine
moiety can be accessed by addition of Hantzsch ester to the reaction mixture.
G. Pelletier, W. S. Bechara, A. B. Charette, J. Am. Chem. Soc., 2010,
132, 12817-12819.
A one-pot reaction for the transformation of common secondary amides into amines
with C-C bond formation consists of in situ amide activation with Tf2O
followed by partial reduction and addition of C-nucleophiles. The method is
general in scope and allows the use of both hard nucleophiles (RMgX, RLi) and
soft nucleophiles, as well as enolates. With soft nucleophiles the presence of
ester, cyano, nitro, and tertiary amide groups are tolerated.
P.-Q. Huang, Y.-H. Huang, K.-J. Xiao, Y. Wang, X.-E. Xia, J. Org. Chem.,
2015,
80, 2861-2868.
A B(C6F5)3-catalyzed chemoselective
hydrosilylation of α,β- and α,β,γ,δ-unsaturated ketones provides the
corresponding non-symmetric ketones in mild reaction conditions. The reaction
tolerates a broad range of reducible functional groups such as alkynyl, alkenyl,
cyano, and aromatic heterocycles.
X.-Y. Zhang, H. Zhang, Y. Dong, J. Yang, S. He, Z.-C. Shi, L. Tang, J.-Y. Wang, J. Org. Chem., 2020, 85,
6578-6592.
The combination of Pd(OAc)2/Et3SiH enables
ligand-controlled non-decarbonylative and decarbonylative conversions of acyl
fluorides. When tricyclohexylphosphine (PCy2) was used as the ligand,
aldehydes were obtained as simple reductive conversion products, whereas
1,2-bis(dicyclohexylphosphino)ethane (Cy2P(CH2)2PCy2,
DCPE) as the ligand favored the formation of hydrocarbons as decarbonylative
reduction products.
Y. Ogiwara, Y. Sakuria, H. Hattori, N. Sakai, Org. Lett.,
2018, 20, 4164-4167.
The combination of Pd(OAc)2/Et3SiH enables
ligand-controlled non-decarbonylative and decarbonylative conversions of acyl
fluorides. When tricyclohexylphosphine (PCy2) was used as the ligand,
aldehydes were obtained as simple reductive conversion products, whereas
1,2-bis(dicyclohexylphosphino)ethane (Cy2P(CH2)2PCy2,
DCPE) as the ligand favored the formation of hydrocarbons as decarbonylative
reduction products.
Y. Ogiwara, Y. Sakuria, H. Hattori, N. Sakai, Org. Lett.,
2018, 20, 4164-4167.
The use of hydrosilanes as reducing agents in the presence of a palladium
catalyst enables an efficient synthesis of aldehydes from acid chlorides. A
simple mixture of commercially available Pd(dba)2 and Mes3P
catalyzed the reduction of various acid chlorides including aliphatic acid
chlorides and α,β-unsaturated acid chlorides to the corresponding aldehydes in
good to high yields under mild reaction conditions.
T. Fujihara, C. Cong, T. Iwai, J. Terao, Y. Tshuji, Synlett, 2012, 23,
2389-2392.
A palladium-catalyzed reduction of 2-pyridinyl esters using hydrosilanes is
applicable to the preparation of aliphatic, aromatic, and α,β-unsaturated
aldehydes. Various functional groups, such as fluoro, methoxy, aldehyde, acetal,
and ester, are tolerated.
J. Nakanishi, H. Tatamidani, Y. Fukumoto, N. Chatani, Synlett,
2006, 869-872.
An [IrCl(cod)]2/2,6-bis(benzimidazol-2'-yl)pyridine complex catalyzes
a reduction of alkyl chlorides using triethylsilane. Primary, secondary,
tertiary, and benzylic C-Cl bonds are effectively dehalogenated. The tridentate
N-ligand can be easily prepared in one step from commercially available
reagents.
T. Fukuyama, Y. Hamada, I. Ryu, Synthesis, 2021, 53,
3404-3408.
A ligandless palladium-catalyzed reductive carbonylation of aryl iodides for the
synthesis of aromatic aldehydes proceeded effectively even under ambient
temperature and pressure.
W. Han, B. Liu, J. Chen, Q. Zhou,
Synlett, 2017, 28, 835-840.
A palladium-catalyzed formylation of aryl halides with isocyanide in the
presence of Et3SiH provides important aldehydes in good yield. This
reaction offers mild conditions, convenient operation, low toxicity, and wide
functional group tolerance.
X. Jiang, J.-M. Wang, Y. Zhang, Z. Chen, Y.-M. Zhu, S.-J. Ji, Org. Lett., 2014,
16, 3492-3495.
Optimizations to generate CuH in situ have led to an efficient and
inexpensive hydrosilylation method for dialkyl ketones.
B. H. Lipshutz, C. C. Caires, P. Kuipers, W. Chrisman, Org. Lett., 2003, 5, 3085-3088.
A regioselective reductive ring opening of benzylidene acetals in carbohydrate
derivatives using triethylsilane and molecular iodine is fast and compatible
with most of the functional groups encountered in oligosaccharide synthesis, and
offers excellent yields. The reaction conditions are equally effective in
thioglycosides.
R. Panchadhayee, A. K. Misra, Synlett, 2010,
1193-1196.
Aliphatic carboxyl derivatives (acids, acyl chlorides, esters) and
aldehydes were efficiently reduced to the methyl group by HSiEt3
in the presence of catalytic amounts of B(C6F5)3.
Aromatic carboxylic acids, as well as other carbonyl functional
equivalents, underwent smooth partial reduction to the corresponding
TES-protected benzylic alcohols.
V. Gevorgyan, M. Rubin, J.-X. Liu, Y. Yamamoto, J. Org. Chem, 2001, 66, 1672-1675.
Aliphatic carboxyl derivatives (acids, acyl chlorides, esters) and
aldehydes were efficiently reduced to the methyl group by HSiEt3
in the presence of catalytic amounts of B(C6F5)3.
Aromatic carboxylic acids, as well as other carbonyl functional
equivalents, underwent smooth partial reduction to the corresponding
TES-protected benzylic alcohols.
V. Gevorgyan, M. Rubin, J.-X. Liu, Y. Yamamoto, J. Org. Chem, 2001, 66, 1672-1675.
Proper solvent selection between Cl(CH2)2Cl and CF3CH2OH
was the key to high yields in a deoxygenation of propargyl alcohols in the
presence of Et3SiH and H3[PW12O40]·nH2O
as catalyst. Under similar conditions, the deoxygenation of allyl alcohols
proceeded to give thermodynamically stable alkenes with migration of the double
bonds in good yields.
M. Egi, T. Kawai, M. Umemura, S. Akai, J. Org. Chem., 2012,
77, 7092-7097.
In situ generation of molecular hydrogen by addition of triethylsilane to
palladium on charcoal results in rapid and efficient reduction of multiple bonds,
azides, imines, and nitro groups, as well as deprotection of benzyl and allyl
groups under mild, neutral conditions.
P. K. Mandal, J. S. McMurray, J. Org. Chem.,
2007,
72, 6599-6601.
A β-boron effect accounts for high regioselectivity in electrophilic addition
reactions to allylic MIDA (N-methyliminodiacetic acid) boronates. The
boryl moiety is retained in the product when B(MIDA) is used as the nucleophilic
stabilizer.
Y. Li, W.-X. Fan, S. Luo, A. Tofimova, Y. Liu, J.-H. Xue, L. Yang, Q. Li, H.
Wang, A. K. Yudin, J. Am. Chem. Soc.,
2023, 145, 7548-7558.
The use of a Cu(III)-CF3 reagent and a silane enables an efficient
and selective hydro-trifluoromethylation of terminal alkynes in DMF to provide
1,2-disubstituted trifluoromethylated Z-alkenes. The unusual Z-selectivity
and the compatibility of various functional groups make this reaction
complementary to previously reported methods producing predominantly E-products.
S.-L. Zhang, C. Xiao, J. Org. Chem., 2018, 83,
10908-10915.
A new procedure for catalytic reductive coupling of aldehydes and alkynes
uses Ni(COD)2 with an imidazolium carbene ligand as the catalyst and
triethylsilane as the reducing agent.
G. M. Mahandru, G. Liu, J. Montgomery, J. Am. Chem. Soc., 2004, 126, 3698-3699.
An intermolecular reductive coupling of ynoates and aldehydes in the presence of
a silane using catalytic amounts of Ni(COD)2, an N-heterocyclic
carbene ligand, and PPh3 delivers invaluable silyl-protected
γ-hydroxy-α,β-enoates. This methodology provides a quick entry to many other
1,4-difunctional compounds and oxygen-containing five-membered rings. The
intermediacy of metallacycles in the catalytic process has been established.
S. K. Rodrigo, H. Guan, J. Org. Chem., 2012,
77, 8303-8309.
A three-component nickel-catalyzed coupling of enals, alkynes, and silanes forms
an enol silane and a trisubstituted alkene with >98:2 stereoselectivity. The
reaction tolerates a broad range of functionality including aldehydes, ketones,
esters, free hydroxyls, and basic secondary amines.
A. Herath, J. Montgomery, J. Am. Chem. Soc., 2008,
130, 8132-8133.
The use of a catalytic amount of PtCl2 enables the conversion of
α-hydroxypropargylsilanes to (Z)-silylenones through a highly selective
silicon migration via alkyne activation. The complementary (E)-silylenones are
accessed by a regioselective hydrosilylation of the ynone precursor.
D. A. Rooke, E. M. Ferreira, J. Am. Chem. Soc., 2010,
132, 11926-11928.
Aldehyde α-hydroperoxides can be accessed from α-substituted acroleins with
triethylsilane and water under Pd/C catalysis and aerobic conditions via a Pd/C-catalyzed
conjugate reduction step and a subsequent hydroperoxidation step. Upon
reduction, 2,2-disubstituted 1,2-diols are obtained.
S. Tuokko, P. M. Pihko,
Synlett, 2016, 27, 1649-1652.
A nickel-catalyzed coupling of enones or enals with alkynes in the presence
of silane and titanium alkoxide reductants provides direct access to skipped
diene products via a net four-electron reductive coupling and deoxygenation. A new class of
well-defined nickel(0) precatalysts bearing an unhindered N-heterocyclic carbene
ligand is essential for the
efficiency of the transformation.
D. P. Todd, B. B. Thompson, A. J. Nett, J. Montgomery, J. Am. Chem. Soc., 2015,
137, 12788-12791.
A 1:1 mixture of the (π-allyl)palladium complex (η3-C3H5)Pd(Cl)PCy3
and NaB[3,5-C6H3(CF3)2]4
catalyzed the cycloisomerization of functionalized 1,6-dienes in the presence of
HSiEt3 to provide 1,2-disubstituted cyclopentenes in good yield.
R. A. Widenhoefer, N. S. Perch,
Org. Lett., 1999, 1, 1103-1105.
Indium hydride (Cl2InH) was generated by the transmetalation of InCl3
with Et3SiH. In the previously reported system (NaBH4-InCl3), the coexistent borane can
cause side reactions. The use of Et3SiH instead of NaBH4 affords effective hydroindation of alkynes.
N. Hayashi, I. Shibata, A. Baba, Org. Lett., 2004, 6, 4981-4983.
Medium-sized cyclic ethers have been effectively synthesized through
intramolecular reductive coupling of dialdehydes in the presence of a
hydrosilane and low loadings of AgNTf2 as catalyst at 25°C. The
catalytic system is also suitable for the coupling of two different
monoaldehydes to provide unsymmetrical ethers. This protocol features broad
functional group compatibility and high product diversity.
T. Liang, G. Dong, C. Li, X. Xu, Z. Xu, Org. Lett.,
2022, 24, 1817-1821.
An operationally simple and efficient strategy for the synthesis of
substituted tetrahydrofurans from readily available cis-butene-1,4-diol
is based on a redox-relay Heck reaction, that generates cyclic hemiacetals. A
subsequent reduction provides the corresponding 3-aryl tetrahydrofurans.
Furthermore, the hemiacetals can also serve as precursors to a range of
disubstituted tetrahydrofurans.
T. J. M. Byrne, M. E. Mylrea, J. D. Cuthbertson, Org. Lett., 2023, 25,
2361-2365.
Indium hydride (Cl2InH) was generated by the
transmetalation of InCl3 with Et3SiH. In the previously
reported system (NaBH4-InCl3), the coexistent borane can
cause side reactions. The use of Et3SiH instead of NaBH4
affords effective hydroindation of alkynes.
N. Hayashi, I. Shibata, A. Baba, Org. Lett., 2004, 6, 4981-4983.
Indium hydride (Cl2InH) was generated by the
transmetalation of InCl3 with Et3SiH. In the previously
reported system (NaBH4-InCl3), the coexistent borane can
cause side reactions. The use of Et3SiH instead of NaBH4
affords effective hydroindation of alkynes.
N. Hayashi, I. Shibata, A. Baba, Org. Lett., 2004, 6, 4981-4983.
Indium hydride (Cl2InH) was generated by the
transmetalation of InCl3 with Et3SiH. In the previously
reported system (NaBH4-InCl3), the coexistent borane can
cause side reactions. The use of Et3SiH instead of NaBH4
affords effective hydroindation of alkynes.
N. Hayashi, I. Shibata, A. Baba, Org. Lett., 2004, 6, 4981-4983.
The use of Et3SiH and a catalytic amount of I2 enables
transition-metal-free, intramolecular hydroalkoxylation/reduction and
hydroamination/reduction of unactivated alkynes at room temperature to provide
2,4- and 2,5-disubstituted pyrrolidines as well as a 2,3-disubstituted
tetrahydrofurans with high diastereoselectivity.
S. Fujita, M. Shibuya, Y. Yamamoto, Synthesis, 2017,
49, 4199-4204.
An Al(OTf)3-catalyzed cascade cyclization and ionic hydrogenation
reaction of nitrogen substituted ketoamides enables an efficient and versatile
synthesis of N-substituted lactams, pyrrolindinones, piperidones, and
structurally related heterocycles in good yields.
J. Qi, C. Sun, Y. Tian, X. Wang, G. Li, Q. Xiao, D. Yin, Org. Lett., 2014,
16, 190-192.
Stereoselective syntheses of pyrrolidines and piperidines bearing hydrophobic
chains have been achieved through a metal free, Lewis acid-mediated 5/6-endo-dig
reductive hydroamination cascade of enynyl amines. The brevity of the developed
strategy allowed for the collective stereoselective total synthesis of various
alkaloids.
S. J. Gharpure, R. K. Patel, K. S. Gupta, Org. Lett., 2023, 25,
5850-5855.
An efficient transition-metal-free transfer hydrogenative cascade reaction
between ortho-nitroanilines and benzyl amines or alcohols provides
benzimidazoles in good yields using a combination of KOtBu and Et3SiH
as reagents. The reaction conditions tolerate diverse functional groups.
A. K. Kabi, R. Gujjarappa, A. Roy, A. Sahoo, D. Musib, N. Vodnala, V. Singh,
C. C. Malakar, J. Org. Chem., 2021, 86,
14597-14607.
A B(C6F5)3-catalyzed chemoselective
hydrosilylation of α,β- and α,β,γ,δ-unsaturated ketones provides the
corresponding non-symmetric ketones in mild reaction conditions. The reaction
tolerates a broad range of reducible functional groups such as alkynyl, alkenyl,
cyano, and aromatic heterocycles.
X.-Y. Zhang, H. Zhang, Y. Dong, J. Yang, S. He, Z.-C. Shi, L. Tang, J.-Y. Wang, J. Org. Chem., 2020, 85,
6578-6592.
Palladium-catalyzed reduction of aromatic nitro groups to amines can be
accomplished in high yield, with wide functional group tolerance and short
reaction times at r.t. using aqueous potassium fluoride and
polymethylhydrosiloxane (PMHS) for aromatic nitro groups. Aliphatic nitro
compounds are reduced to the corresponding hydroxylamines using
triethylsilane instead of PMHS/KF.
R. J. Rahaim, R. E. Maleczka (Jr.), Org. Lett., 2005, 7, 5087-5090.
The sensitive azidocarbenium ion intermediate can be trapped with various
nucleophiles to provide azides in excellent chemoselectivity. The method enables
the chemoselective synthesis of primary and secondary benzyl azides from
aldehydes in a one-pot reaction.
S. Pramanik, P. Ghorai, Org. Lett., 2014,
16, 2104-2107.
Organic azides are easily and chemoselectively reduced to the corresponding amines by reaction
with dichloroindium hydride under very mild conditions. γ-Azidonitriles
give pyrrolidin-2-imines in an outstanding
cyclization.
L. Benati, G. Bencivenni, R. Leardini, D. Nanni, M. Minozzi, P. Spagnolo, R.
Scialpi, G. Zanardi, Org. Lett., 2006, 8, 2499-2502.
L. Benati, G. Bencivenni, R. Leardini, D. Nanni, M. Minozzi, P. Spagnolo, R.
Scialpi, G. Zanardi, Org. Lett.,
2006,
8, 2499-2502.
Reduction of ethanethiol esters of α-amino acids to α-amino aldehydes by
triethylsilane and catalytic palladium-on-carbon is described. α-Amino aldehydes
with Boc, Cbz, or Fmoc protection could be obtained without racemization in high
yield.
H. Tokuyama, S. Yokoshima, S.-C. Lin, L. Li, T. Fukuyama, Synthesis,
2002, 1121-1123.
H. Tokuyama, S. Yokoshima, T. Yamashita, S.-C. Lin, L. Li, T. Fukuyama,
J. Braz. Chem. Soc., 1998, 9, 381-387.