Transition-Metal-Free N-Arylation of Amines by Triarylsulfonium Triflates

Article abstract of DOI:10.1002/chem.201802269

A simple and efficient method for transition-metal-free N-arylation of various amines by triarylsulfonium triflates is described. Both aliphatic and aromatic amines were smoothly converted at 80 °C in the presence of tBuOK or KOH to give the corresponding mono N-arylated products in good to high yields. The molar ratios of the reactants and the choice of bases had a big effect on the reaction. When a large excess of [Ph₃S][OTf] and tBuOK were employed for primary amines under the standard conditions, the bis(N-phenyl) products were predominantly formed. This method was also applicable to the synthesis of bioactive N-phenyl amino acid derivatives. The control experiments, the deuterium labelling study, and the presence of regioisomers of N-arylated products when using 4-substituted triarylsulfonium triflates suggested that the reaction might proceed through an aryne intermediate. The present protocol demonstrated that triarylsulfonium salts are versatile arylation reagents in the construction of C_Ar?N bonds.

Full text of DOI:10.1002/chem.201802269

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Accepted Article
Title: Transition Metal-Free N-Arylation of Amines by Triarylsulfonium
Triflates
Authors: Ze-Yu Tian, Xiao-Xia Ming, Han-Bing Teng, Yu-Tian Hu, and
Cheng-Pan Zhang
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To be cited as: Chem. Eur. J. 10.1002/chem.201802269
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Transition Metal-Free N-Arylation of Amines by Triarylsulfonium
Triflates
Ze-Yu Tian[a], Xiao-Xia Ming[a], Han-Bing Teng*[a], Yu-Tian Hu[a], Cheng-Pan Zhang*[a]
Abstract: A simple and efficient method for transition metal-free N-
arylation of various amines by triarylsulfonium triflates is described.
Both aliphatic and aromatic amines were smoothly converted at 80
oC in the presence of t-BuOK or KOH to give the corresponding
mono N-arylated products in good to high yields. The molar ratios of
the reactants and the choice of bases had a big effect on the
reaction. When a large excess of [Ph3S][OTf] and t-BuOK were
employed for primary amines under the standard conditions, the
bis(N-phenylated) products were predominantly formed. This method
was also applicable to the synthesis of bioactive N-phenyl amino
acid derivatives. The control experiments, the deuterium labelling
study, and the presence of regioisomers of N-arylated products
when using 4-substituted triarylsulfonium triflates suggested that the
reaction might proceed through an aryne intermediate. The present
protocol demonstrated that triarylsulfonium salts are versatile
arylation reagents in the construction of CAr-N bonds.
On the other hand, triarylsulfonium salts ([Ar3S]X, X = OTf, BF4,
PF6, etc.) are versatile agents in organic chemistry and materials
science.[8,9] Recently, the Pd-catalyzed arylation of arylboronic
acids, alkenes, and alkynes by [Ar3S][OTf], the visible-light
photocatalytic reduction and radical addition of [Ar3S]X to
alkenes, and the transition metal-free aromatic ipso-substitution
of [Ar3S][OTf] with [18F]fluorides have evidenced their great
usefulness in the C-C and C-F bond formation reactions.[9,10]
Although the transition metal-free reactions of primary anilines
and secondary aliphatic amines with diaryliodonium salts under
alkaline conditions have been documented, producing various
arylamines via nucleophilic aromatic substitution, aryne
intermediates, or ligand exchange/reductive elimination
processes[7a-d], the interactions between triarylsulfonium salts
and amines or their derivatives are least studied.[11] As a class of
alternative and emerging aryl transfer sources, triarylsulfonium
salts have featured several advantages such as non-volatility,
easy preparation, non-toxicity, moderate reactivity, and broad
structural diversity. Importantly, the thermal gravimetric analysis
showed that triphenylsulfonium triflate ([Ph3S][OTf]) has a much
higher onset decomposition temperature (405.8 oC) than
Arylamines widely exist in the structural backbones of ligands,
pharmaceuticals, agrochemicals, natural products, and
functional materials.[1,2] Synthesis of arylamines, previously
mainly relying on nitroarene reduction, has received great
advancement in the transition metal-catalyzed or -free reactions
of amine nucleophiles or their electrophilic analogues with
appropriate arylation reagents during the last two decades.[2-7]
So far, a great number of aryl chlorides, bromides, iodides,
sulfonates, iodonium salts, and other pseudo halides, as well as
aryne precursors, have been confirmed to be viable arylation
reagents in these reactions, providing the corresponding N-
arylated products.[1-7]
o
diphenyliodonium triflate ([Ph2I][OTf], 207.0 C) (see supporting
information), hinting at much better thermal stability of the former
than the latter. Nevertheless, application of the advantageous
triarylsulfonium salts as arylation reagents is to date much under
developed compared to the corresponding diaryliodonium
salts.[4a,6-8]
As a continuation of our interest in use of triarylsulfonium salts
for arylation[8a,9], we first tested the reactions of [Ph3S][OTf] with
different types of amines under transition metal-free conditions.
To our delight, the reaction of cyclohexanamine (1a) with
triphenylsulfonium triflate (2a, 1.5 equiv) in toluene in the
presence of t-BuOK (1.2 equiv) at 80 oC under a nitrogen
atmosphere for 24 h gave N-cyclohexylaniline (3a) in 78% yield
(Table S1). The choice of bases had a big impact on the N-
phenylation (Table S1). t-BuONa, CsOH, KOH, and NaOH were
moderately effective, affording 3a in lower yields. Reaction of 1a
o
and 2a with LDA or n-BuLi (at -78 C to room temperature or at
reflux in THF[11]) gave 7-12% of 3a. It should be noted that, in
most reactions, a small amount of N-cyclohexyl-N-phenylaniline
(4a) was formed accompanied with 3a, but it could be easily
removed by column chromatography. Other bases such as
K2CO3, KF, DBU, and NEt3 were completely inert at 80 oC for the
reaction, which didn’t form 3a. Moreover, if the reaction of 1a
o
and 2a was run at 80 C in the absence of base, no desired N-
phenylation product was obtained.
[a]
Z.-Y. Tian, X.-X. Ming, Prof. H.-B. Teng*, Y.-T. Hu, Prof. C.-P.
Zhang*
School of Chemistry, Chemical Engineering and Life Science
Wuhan University of Technology
Then, a brief survey of the reaction temperature showed that a
o
temperature of 80 C was optimal for the reaction of 1a with 2a
205 Luoshi Road, Wuhan 430070, (China)
E-mail: cpzhang@whut.edu.cn,
zhangchengpan1982@hotmail.com, wdthb@163.com
and t-BuOK (Table S2). The solvent had a considerable
influence on the conversion (Table S3). Toluene appeared to be
the best solvent as the reaction of 1a, 2a and t-BuOK in CH3CN,
THF, DMF, m-xylene, DMSO, NMP, or 1,4-dioxane provided 3a
in a decreased yield (11-64%). Furthermore, the molar ratios of
Supporting information for this article is given via a link at the
end of the document. ((Please delete this text if not appropriate))
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1a, 2a and t-BuOK interestingly affected the formation of 3a
(Table S4). When 2a reacted with excess 1a (1.11-2.0 equiv.)
and t-BuOK (1.33-2.4 equiv.) in toluene, 3a was formed in 75-
82% yields. These yields were comparable to that obtained from
the reaction of 1a using 1.5 equiv. 2a (78%). Notably, if 1a was
treated with 2.5 equiv. 2a and 3.0 equiv. t-BuOK at 80 oC for 24
h, the doubly N-phenylated compound (4a) was obtained as the
major product (91% isolated yield) (Table S4). Additionally,
prolonging the reaction time of 1a, 2a, and t-BuOK (1a/2a/t-
BuOK = 1:1.5:1.2 or 1.33:1:1.33) from 24 h to 28 h only slightly
improved the yield of 3a (Table S5). Reaction of 1.33 equiv. 1a
with 2a in toluene in the presence of 1.33 equiv. t-BuOK at 80 oC
for 28 h supplied 3a in 85% yield (or 88% isolated yield on a
large scale). Further extension of the reaction time did not
continuously enhance the yield of 3a.
under the standard conditions to furnish respectively 95% of 3g,
80% of 3h, 84% of 3i, 55% of 3j, and 78% of 3k. There were no
bis(N-phenylated) products observed in the reactions of
secondary amines. The scaled-up syntheses of 3a and 3i by
reactions of 1a and 1i with 2a at a 4.5 or 1.5 mmol scale gave
72% and 63% isolated yields, respectively, demonstrating the
practicality of this method. Furthermore, by minor variation of the
standard conditions in some reactions, e.g., use of 2 equiv. 1c
for 2a, replacement of t-BuOK by KOH for 1e, and employment
of 1.5 equiv. 2a for 1k, the respective desired products were
formed in better yields. These improvements suggested good
flexibility of the conversion.
In addition, the N-phenylation reaction was applicable to
aromatic amines (Table 1). Both KOH and t-BuOK were suitable
bases for the N-phenylation of aniline (1l) (Table S7). Reaction
of 1l (1.33 equiv.) with 2a in the presence of KOH (1.33 equiv.)
at 80 oC for 28 h afforded 3l in 68% yield. Aniline derivatives
bearing either electron-donating or -withdrawing groups (e.g.,
methoxy (1m), methyl (1n), trifluoromethoxy (1o), chloro (1p),
bromo (1q), or tert-butyl carbamate (BocNH, 1r)) reacted under
the same conditions to provide the mono N-phenylated products
(3m-r) in 25-90% yields. The electron-withdrawing substituents
on the aryl rings of anilines (1o-q) appeared to benefit the N-
phenylation. Analogously, treatment of benzo[d][1,3]dioxol-5-
amine (1s), 2-allylaniline (1t), naphthalen-1-amine (1u), and
quinolin-8-amine (1v) with 2a/KOH supplied the expected N-
phenyl anilines (3s-v) in 68-93% yields. The electron-deficient
quinolin-8-amine (1v) gave a higher yield of N-phenylated
product than the electron-rich congener (1u) as well. Secondary
aromatic amines such as N-allylaniline (1w), 10H-phenoxazine
(1x), 10H-phenothiazine (1y), 9H-carbazole (1z), 3-methyl-1H-
indole (1aa), and 1H-indole (1ab) reacted mildly with 2a under
the standard conditions to produce the corresponding N-
phenylated products (3w-ab) in 45-99% yields. 1H-indoles
seemed to be less effective substrates than phenoxazine,
phenothiazine, and carbazole for the reaction. The BocNH group,
the carbon-carbon double bonds and the heterocyclic moieties
of substrates were well tolerated, illustrating good compatibility
of the reaction.
Table 1. Mono N-phenylation of amines by triphenylsulfonium triflate in the presence
of t-BuOK or KOH
To further verify the usefulness of the method, several bioactive
molecules (1ac-ae) were examined (Table 1). It was remarkable
that tert-butyl L-prolinate (1ac) and tert-butyl L-phenylalaninate
(1ae) reacted with 2a and t-BuOK to give desirably the racemic
N-phenylated products (3ac and 3ae) in good yields (see SI).
The use of 1.5 equiv. 2a and 1.2 equiv. t-BuOK to mix with tert-
butyl glycinate (1ad) and 1ae could clearly improve the yields of
3ad and 3ae.
[a] Reaction conditions: amine 1 (0.4 mmol), 2a (0.3 mmol), t-BuOK (0.4
mmol), toluene (2 mL), 80 oC, N2, 28 h. Isolated yield. [b] The reaction was run
on a 4.5 mmol scale at 60 oC. [c] Amine 1 (0.6 mmol). [d] KOH (0.48 mmol)
was used instead of t-BuOK (0.4 mmol). [e] The reaction was run on a 1.5
mmol scale. [f] Reaction conditions: amine 1 (0.2 mmol), 2a (0.3 mmol), t-
BuOK (0.24 mmol), toluene (2 mL), 80 oC, N2, 24 h. Isolated yield.
Next, we chose an assembly of amine 1 (0.4 mmol), 2a (0.3
o
Bis(N-phenylation) of amines by a large excess of 2a in the
presence of t-BuOK was also achieved. As above, reaction of 1a
with 2.5 equiv. 2a and 3.0 equiv. t-BuOK at 80 oC for 24 h
provided 91% of the bis(N-phenylated) product (4a). In a similar
manner, treatment of 1b, 1c, 1d, 1l, 1n, cyclopropanamine (1af),
2-methylpropan-2-amine (1ag), and 2-bromo-4-chloroaniline
(1ah) with 2a (2.5 equiv.)/t-BuOK (3.0 equiv.) gave respectively
the bis(N-phenylated) products (4b-i) in moderate to high yields
(Table 2). The bulky adamantanyl group in 1d somewhat
affected the bis(N-phenylation), affording a relatively low yield of
mmol), t-BuOK (0.4 mmol), toluene (2 mL), 80 C, N2, and 28 h
as the standard reaction conditions to probe the substrate scope
of the N-phenylation (Table 1). Primary aliphatic amines such as
cyclopentanamine (1b), 3-((2-ethylhexyl)oxy)propan-1-amine
(1c), (3s,5s,7s)-adamantan-1-amine (1d), phenylmethanamine
(1e), and 2-phenylethan-1-amine (1f) were smoothly converted
to give the corresponding mono N-phenylated products (3b-f) in
65-78% yields. Similarly, secondary aliphatic amines like
pyrrolidine (1g), piperidine (1h), morpholine (1i), thiomorpholine
(1j), and 1,2,3,4-tetrahydroisoquinoline (1k) reacted with 2a
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the desired product. Furthermore, the results gained from the
reaction condition optimization suggested that a group of
2a/KOH was poorly effective for the one-pot bis(N-phenylation)
of aniline (Table S8). Reaction of 1l with 2a (2.5 equiv) in the
presence of KOH (3.0 equiv) still gave mono N-phenylated
amine as the main product (Table S8). All of these observations
combined implied that the selective mono- and bis(N-
phenylation) of primary amines by [Ph3S][OTf] could be simply
tuned by varying the molar equivalent of 2a and the bases.
standard reactions of 2-allylaniline (1t) and N-allylaniline (1w)
with 2a, providing 3t and 3w with the carbon-carbon double
bonds survived, might also exclude a radical mechanism.
Table 4. N-Arylation of amines by triarylsulfonium triflates in the presence of t-
BuOK or KOH
Table 2. Bis(N-phenylation) of amines by triphenylsulfonium triflate in the
presence of t-BuOK.
[a] Reaction conditions: cyclohexanamine (1a, 0.2 mmol), 2b-e (0.15 mmol), t-
BuOK (0.2 mmol), toluene (2 mL), 80 oC, N2, 28 h. Isolated yield. 2b: R = Br;
2c: R = Cl; 2d: R = F; 2e: R = OMe. [b] The reaction was run at 100 oC. [c]
Reaction conditions: aniline (1l, 0.2 mmol), 2d-e (0.15 mmol), KOH (0.24
mmol), toluene (2 mL), 80 oC, N2, 28 h. Isolated yield. The molar ratios of p-
and m-isomers were determined by NMR spectroscopy.
[a] Reaction conditions: amine 1 (0.2 mmol), 2a (0.5 mmol), t-BuOK (0.6
mmol), toluene (4 mL), 80 oC, N2, 24 h. Isolated yield. [b] 36 h.
Table 3. Control experiments for understanding the reaction mechanism
Entry
1[a]
Additive
TEMPO (1.0 equiv.)
TEMPO (1.0 equiv.)
none
3a (%)
62
4a (%)
Scheme 1. N-Phenylation of 1k by deuterated triphenylsulfonium triflate (2a-
D)
4
8
4
2[b]
70
Further studies showed that other triarylsulfonium triflates were
also available reagents for N-arylation of amines (Table 4).
Tris(4-bromophenyl)sulfonium triflate (2b) reacted with 1a in the
presence of t-BuOK under the standard conditions to furnish 4-
bromo-N-cyclohexylaniline (3af) in 64% yield and 3-bromo-N-
cyclohexylaniline (3afꞌ) in 35% yield. Similar reaction of tris(4-
chlorophenyl)sulfonium triflate (2c), tris(4-fluorophenyl)sulfonium
triflate (2d), and tris(4-methoxyphenyl)sulfonium triflate (2e) with
1a gave mixtures of the regioisomers of the corresponding N-
arylated products (3ag/3agꞌ-3ai/3aiꞌ) in good yields. All these
isomers could be easily separated by column chromatography.
However, in the reactions of 2d and 2e with aniline (1l) and KOH,
inseparable mixtures of p- and m-isomers of the N-arylated
products (3aj/3ajꞌ and 3m/3mꞌ) were obtained, the molar ratios
of which were determined by NMR spectroscopy. The presence
of regioisomers of products in the reactions of 2b-e implied that
the reaction might proceed via an aryne intermediate. Since the
aryne intermediates have been demonstrated as highly reactive
and inseparable species,[13] they are usually generated in situ in
the reactions. Moreover, the reaction of 1k with deuterated
3[a,c]
81
[a] Reaction conditions: 1a (0.2 mmol), 2a (0.15 mmol), t-BuOK (0.2 mmol),
toluene (2 mL), 80 oC, N2, 28 h. The yields were determined by HPLC using 3a
and 4a as external standards (3a: tR = 5.930 min, 4a: tR = 16.823 min, λmax
=
249 nm (for 3a), water / methanol = 10 / 90 (v / v)). [b] Reaction conditions: 1a
(0.2 mmol), 2a (0.3 mmol), t-BuOK (0.24 mmol). [c] The reaction was run in
the darkness.
It was well known that [Ar3S]X can be readily initiated by UV-
visible light or reductants to form aryl radicals for many chemical
reactions.[8] t-BuOK is an efficient reductant in transition metal-
free homolytic aromatic substitution (HAS) of aryl halides (ArX),
which generates aryl radicals via a single-electron transfer (SET)
between ArX and t-BuOK.[12] Besides, the aromatic nucleophilic
ipso-substitution of [Ar3S][OTf] by fluorides is also reported.[10b-c]
To gain an insight into the mechanism of this N-phenylation
reaction with [Ar3S][OTf], several control experiments were
carried out (Table 3). It was found that both the reaction of
excess 1a/t-BuOK with 2a and the reaction of 1a with excess
2a/t-BuOK in the presence of TEMPO (1.0 equiv.) under the
standard conditions afforded slightly lower yields of the desired
product (3a) (entries 1 and 2). When a mixture of 1a (0.2 mmol),
2a (0.15 mmol), t-BuOK (0.24 mmol), and toluene (2 mL) was
heated at 80 oC in the darkness for 28 h, 3a was obtained in
81% yield (entry 3). These data suggested that the reaction
might proceed through a non-radical pathway. Again, the
o
triphenylsulfonium triflate (2a-D) at 80 C for 28 h gave 3k-D in
81% yield with 82% ortho-H form (Scheme 1), suggesting a
predominant N-H addition process to a benzyne intermediate.
Nonetheless, the ipso-substitution mechanism occurring on the
aromatic rings of arylsulfonium salts couldn’t be fully excluded at
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10.1002/chem.201802269
Chemistry - A European Journal
COMMUNICATION
this stage as the ortho-H form of 3k-D was not 100% produced,
regardless of the H-D exchanges in the reaction system.
Keywords: transition metal-free • N-arylation • aryne •
triarylsulfonium triflates
In conclusion, we have developed a transition metal-free
method for N-arylation of amines by using triarylsulfonium
triflates as arylation reagents and t-BuOK or KOH as a base.
Various aliphatic and aromatic amines including primary and
secondary were readily transformed to give the corresponding
N-arylated products in good to high yields under mild conditions.
The molar ratios of reactants and the types of bases greatly
affected the reactions of primary amines. When a large excess
of [Ph3S][OTf] was employed with using t-BuOK as a base, the
bis(N-phenylated) compounds were obtained as the major
products. In contrast, the secondary amines supplied only mono
N-phenylated products even with much excess [Ar3S][OTf] and t-
BuOK. The reaction also allowed a simple, yet powerful and
reliable synthesis of bioactive N-phenyl amino acid derivatives.
The control experiments, the deuterium labelling study, and the
formation of regioisomers of N-arylated products using 4-
[1]
a) A. G. Siraki, in Advances in Molecular Toxicology (Edited by J. C.
Fishbein), Elsevier, Amsterdam, 2013, 7, chapter 2, 39-82; b) J. Jiao, K.
Murakami, K. Itami, ACS Catal. 2016, 6, 610-633; c) M. Liang, J. Chen,
Chem. Soc. Rev. 2013, 42, 3453-3488.
[2]
a) M. Kannan, M. Sengoden, T. Punniyamurthy, in Arene Chemistry:
Reaction Mechanisms and Methods for Aromatic Compounds (edited
by J. Mortier), 1st Edition, chapter 20, John Wiley & Sons, Inc, 2016; b)
M. Stradiotto, R. J. Lundgren, in Ligand Design in Metal Chemistry:
Reactivity and Catalysis (edited by M. Stradiotto, R. J. Lundgren), 1st
Edition, chapter 5, John Wiley & Sons, Ltd, 2016.
[3]
[4]
[5]
[6]
a) J. F. Hartwig, Acc. Chem. Res. 2008, 41, 1534-1544; b) S. Bhunia, G.
G. Pawar, S. V. Kumar, Y. Jiang, D. Ma, Angew. Chem. Int. Ed. 2017,
56, 16136-16179; Angew. Chem. 2017, 129, 16352-16397; c) P. Ruiz-
Castillo, S. L. Buchwald, Chem. Rev. 2016, 116, 12564-12649.
(a) T. Wirth, in Hypervalent Iodine Chemistry, Topics in Current
Chemistry 373, Springer, 2016. (b) K. B. Pal, M. Mahanti, U. J. Nilsson,
Org. Lett. 2018, 20, 616-619. (c) Y. Yoshida, S. Otsuka, K. Nogi, H.
Yorimitsu, Org. Lett. 2018, 20, 1134-1137.
substituted triarylsulfonium triflates suggested
a plausible
Electrophilic amination (Selected reviews): a) X. Dong, Q. Liu, Y. Dong,
H. Liu, Chem. Eur. J. 2017, 23, 2481-2511; b) C. E. Hendrick, Q. Wang,
J. Org. Chem. 2017, 82, 839-847; c) K. Murakami, G. J. P. Perry, K.
Itami, Org. Biomol. Chem. 2017, 15, 6071-6075.
mechanism via an aryne intermediate for the reaction.
Advantages of this method include a wide range of substrates,
transition metal-free conditions, tunable mono- or bis(N-
phenylation) of primary amines, and excellent thermal stability of
[Ar3S][OTf] (compared to the diaryliodonium salts used for CAr-N
bond formation). Application of [Ar3S][OTf] as promising arylation
reagents in other transformations is currently on the way in our
lab.
Selected examples for recent transition metal-catalyzed N-arylation with
diaryliodonium salts: a) K. Matsuzaki, K. Okuyama, E. Tokunaga, N.
Saito, M. Shiro, N. Shibata, Org. Lett. 2015, 17, 3038-3041; b) X. Pang,
C. Chen, X. Su, M. Li, L. Wen, Org. Lett. 2014, 16, 6228-6231; c) S. G.
Modha, M. V. Popescu, M. F. Greaney, J. Org. Chem. 2017, 82, 11933-
11938; d) K. Aradi, Á. Mészáros, B. L. Tóth, Z. Vincze, Z. Novák, J. Org.
Chem. 2017, 82, 11752-11764; e) P. Li, G. Cheng, H. Zhang, X. Xu, J.
Gao, X. Cui, J. Org. Chem. 2014, 79, 8156-8162; f) D. Zhu, Q. Liu, B.
Luo, M. Chen, R. Pi, P. Huang, S. Wen, Adv. Synth. Catal. 2013, 355,
2172-2178; g) J. Li, H. Wang, Y. Hou, W. Yu, S. Xu, Y. Zhang, Eur. J.
Org. Chem. 2016, 2388-2392.
Experimental Section
In
a nitrogen-filled glovebox, a sealed tube was charged with
[7]
Selected examples for recent transition metal-free N-arylation with
diaryliodonium salts: a) M. A. Carroll, R. A. Wood, Tetrahedron 2007,
63, 11349-11354; b) A. H. Sandtorv, D. R. Stuart, Angew. Chem. Int.
Ed. 2016, 55, 15812-15815; Angew. Chem. 2016, 128, 16044-16047;
(c) S. K. Sundalam, A. Nilova, T. L. Seidl, D. R. Stuart, Angew. Chem.
Int. Ed. 2016, 55, 8431-8434; Angew. Chem. 2016, 128, 8571-8574; d)
D. R. Stuart, Synlett 2017, 28, 275-279; e) F. Tinnis, E. Stridfeldt, H.
Lundberg, H. Adolfsson, B. Olofsson, Org. Lett. 2015, 17, 2688-2691; f)
M. Wang, Z. Huang, Org. Biomol. Chem. 2016, 14, 10185-10188; g) T.
Sasaki, K. Moriyama, H. Togo, J. Org. Chem. 2017, 82, 11727-11734.
a) Z.-Y. Tian, Y.-T. Hu, H.-B. Teng, C.-P. Zhang, Tetrahedron Lett.
2018, 59, 299-309 and the references cited therein; b) J. V. Crivello,
Adv. Polym. Sci. 1984, 62, 1-48.
triphenylsulfonium triflate (2a, 123.6 mg, 0.3 mmol), t-BuOK (44.8 mg,
0.4 mmol), cyclohexanamine (1, 39.6 mg, 0.4 mmol), and toluene (2 mL)
with vigorous stirring. The mixture was heated at 80 oC for 28 h, cooled to
room temperature, and concentrated to dryness under reduced pressure.
The residue was purified by column chromatography on silica gel using a
mixture of petroleum ether / ethyl acetate = 40 : 1 (v / v) as eluents to
give N-cyclohexylaniline (3a) as a yellow oil (46.2 mg, 88%). 1H NMR
(500 MHz, CDCl3) δ 7.17 (t, J = 8.0 Hz, 2H), 6.67 (t, J = 7.5 Hz, 1H), 6.60
(d, J = 7.5 Hz, 2H), 3.52 (brs, 1H), 3.27 (m, 1H), 2.08 (dm, J = 12.5 Hz,
2H), 1.78 (dm, J = 13.5 Hz, 2H), 1.67 (dm, J = 13.0 Hz, 1H), 1.43-1.35 (m,
2H), 1.29-1.23 (m, 1H), 1.20-1.13 (m, 2H). 13C NMR (126 MHz, CDCl3) δ
147.4, 129.3, 116.9, 113.2, 51.7, 33.5, 26.0, 25.1.
[8]
[9]
a) X.-Y. Wang, H.-X. Song, S.-M. Wang, J. Yang, H.-L. Qin, X. Jiang,
C.-P. Zhang, Tetrahedron 2016, 72, 7606-7612; b) S.-M. Wang, H.-X.
Song, X.-Y. Wang, N. Liu, H.-L. Qin, C.-P. Zhang, Chem. Commun.
2016, 52, 11893-11896; c) Z.-Y. Tian, S.-M. Wang, S.-J. Jia, H.-X.
Song, C.-P. Zhang, Org. Lett. 2017, 19, 5454-5457.
Acknowledgements
[10] a) S. Donck, A. Baroudi, L. Fensterbank, J.-P. Goddard, C. Ollivier, Adv.
Synth. Catal. 2013, 355, 1477-1482; b) L. Mu, C. R. Fischer, J. P.
Holland, J. Becaud, P. A. Schubiger, R. Schibli, S. M. Ametamey, K.
Graham, T. Stellfeld, L. M. Dinkelborg, L. Lehmann, Eur. J. Org. Chem.
2012, 889-892; c) K. Sander, T. Gendron, E. Yiannaki, K. Cybulska, T.
L. Kalber, M. F. Lythgoe, E. Arstad, Sci. Rep. 2015, 5, 9941.
[11] K. S. Kim, S. M. Ha, J. Y. Kim, K. Kim, J. Org. Chem. 1999, 64, 6483-
6486.
We thank the Wuhan University of Technology, the Fundamental
Research Funds for the Central Universities, the National
Natural Science Foundation of China (21602165), the “Chutian
Scholar” Program from Department of Education of Hubei
Province (China), the “Hundred Talent” Program of Hubei
Province, and the Wuhan Youth Chen-Guang Project
(2016070204010113) for financial support.
[12] C.-L. Sun, Z.-J. Shi, Chem. Rev. 2014, 114, 9219-9280.
[13] a) T. Roy, A. T. Biju, Chem. Commun. 2018, 54, 2580-2594; b) M.
Asamdi, K. H. Chikhalia, Asian J. Org. Chem. 2017, 6, 1331-1348.
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10.1002/chem.201802269
Chemistry - A European Journal
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This article is protected by copyright. All rights reserved.

10.1002/chem.201802269
Chemistry - A European Journal
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Z.-Y. Tian, X.-X. Ming, H.-B. Teng*, Y.-
T. Hu, C.-P. Zhang*
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Transition Metal-Free N-Arylation of
Amines by Triarylsulfonium Triflates
Transition metal-free N-arylation of aliphatic and aromatic amines by [Ar3S][OTf] in
the presence of t-BuOK or KOH gave the mono N-arylated products in good to high
yields. The reaction might proceed via an aryne intermediate. The molar ratios of
the reactants and the choice of bases had a big influence on the reaction. When a
large excess of [Ph3S][OTf] and t-BuOK were employed for primary amines, the
corresponding bis(N-phenylated) compounds were obtained as the major products.
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