Synthesis, Structural Characterization and Catalytic Activities of Sulfur-Functionalized NHC–Copper(I) Complexes

Article abstract of DOI:10.1002/ejoc.201700523

The synthesis of a family of N-heterocyclic carbene–copper complexes bearing a sulfur moiety by using different copper(I) halides through convenient procedures is reported. The solid-state structures of the presented copper compounds were elucidated based

Full text of DOI:10.1002/ejoc.201700523

A Journal of
Accepted Article
Title: Synthesis, structural characterization and catalytic activities of
sulfur-functionalized NHC copper(I) complexes
Authors: Anna Szadkowska, Ewelina Zaorska, Sebastian Staszko,
Robert Pawłowski, Damian Trzybiński, and Krzysztof Woźniak
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To be cited as: Eur. J. Org. Chem. 10.1002/ejoc.201700523
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10.1002/ejoc.201700523
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Synthesis, structural characterization and catalytic activities of
sulfur-functionalized NHC copper(I) complexes
Anna Szadkowska,*[a],[c] Ewelina Zaorska,[a] Sebastian Staszko,[a] Robert Pawłowski,[a],[b] Damian
Trzybiński [a],[c] and Krzysztof Woźniak [a],[c]
Abstract: The synthesis of a family of N-heterocyclic copper
carbene complexes bearing sulfur moiety using different copper(I)
halides and convenient route procedures have been reported. The
Results and Discussion
solid state structures of presented copper compounds were
elucidated using X-Ray crystallography. Next, obtained complexes
were examined in various catalytic transformations including 1,3-
dipolar cycloaddition of alkynes and azides, A3 coupling reaction and
β-hydroboration.
SYNTHESIS AND CATALYTIC ACTIVITY
The synthesis of sulfur-containing copper(I) NHC complexes
followed the route presented on Scheme 1. At the beginning of
our project, we focused on the examination of saturated NHC
copper analogues containing a thioether chain. In the first two
steps, the preparation of NHC precursor 4 relied on the
application of the dihydroimidazole 3, which was obtained
according to the well-established procedures.[10] In third step, the
treatment of compound 3 with an excess of (phenylthio)methyl
chloride at elevated temperature allowed to obtain the expected
NHC salt 4 with 75% yield (Scheme 1). Subsequently, the non-
symmetrically sulfur-containing NHC precursor 4 was used in
the direct preparation of the copper complexes. The treatment of
the solution of carbene precursor 4 in THF with potassium tert-
butoxide and in the presence of different copper(I) halides gave
the NHC copper complexes: 5Cl, 5Br and 5I as white powders
(Scheme 1).
Introduction
A discovery of a first neutral copper carbene complex by
Arduengo and Raubenheimer became the turning-point in the
development of metal catalytic systems based of NHC ligands.[1]
Since this disclosure, various complexes containing a metal
centre and NHC moiety have been presented.[2] In particular,
NHC complexes based on copper have proven to be important
class of initiators in the organic synthesis.[3],[4] Studies on these
compounds have shown, that modification of NHC ligand cause
considerable differences in reactivity and may have profound
impact on the performance of copper catalysts in various
organometallic reactions.[5]
To date, numerous modifications of the NHC ligands with
various substituents and heteroatoms have been reported.[6]
However, the examples of copper complexes containing
together “mixed” – alkyl and aryl moieties are still relatively rare
in the literature.[7] This change in steric crowding of NHC ligand
by replacement of one of the traditional functional group by less
steric can influence on the catalyst activity. This trend has been
already shown in case of other NHC metal complexes.[8] Based
on these remarks, NHC copper complexes bearing this less
bulkiness substituents are worth to explore and to examine in
more detail.[9] Herein, we present our findings on the preparation
of series of unsymmetrical NHC copper(I) complexes with a less
constrained thioether ligand and screening of their catalytic
activity in various transformations.
Scheme 1. Synthesis of new copper(I) complexes containing saturated NHC
ligands with sulfur moiety.
The compounds bearing halogen atoms: chlorine (5Cl) and
bromine (5Br) were isolated with acceptable yields: 73% and
52%, respectively. In contrary to 5Cl and 5Br, the iodo-
derivative (5I) was obtained with poor yield (38%) and tended
to decompose at fast rate. The structures of these three copper
complexes were verified by 1H and 13C NMR measurements.
Additionally, suitable single crystals of 5Cl and 5Br compounds
for X-Ray diffraction studies were received by slow diffusion of
n-pentane from concentrated solutions of these complexes in
dichloromethane. The molecular structures of 5Cl and 5Br
were presented subsequently, in the paragraph describing the
crystallographic studies (Figure 1 and Figure 2).
Having in hand, the NHC copper complexes containing sulfur
moiety, we began the initial examination of their catalytic
activity. As the model reaction, we chose three component click
reaction of benzyl bromide, phenylacetylene and NaN3 using 5
mol% of 5Cl, 5Br and 5I in various solvents at room
temperature (Table 1).[11], [12], [13]
[a]
Department of Chemistry,
University of Warsaw
Pasteura 1, 02-093 Warsaw, Poland
E-mail: szadkowska.anna@gmail.com
Faculty of Chemistry,
Warsaw University of Technology
Noakowskiego 3, 00-664 Warsaw, Poland
Biological and Chemical Research Centre,
University of Warsaw
[b]
[c]
Zwirki i Wigury 101, 02-089 Warsaw, Poland
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Table 1. Activity of saturated NHC copper complexes containing sulfur moiety
in CuAAC reaction in various solvents.
Entry
[Cu] cat.
Solvent
Yield of P1(%) [a]
1
5Cl
5Br
5I
MeOH
MeOH
MeOH
DCM
73
2
48
3
Traces
32
4
5Cl
5Br
5I
Scheme 2. Synthesis of new copper(I) complexes containing unsaturated
5
DCM
Traces
n. d.
18
NHC ligands with sulfur moiety.
6
DCM
The preparation of the complex 8Cl consisted of three steps.
At the first stage, the commercially available 2,6-
7
5Cl
5Br
5I
DMSO
DMSO
DMSO
n-hexane
EtOAc
THF
diisopropylaniline
diisopropylphenyl)-1H-imidazole
1
was converted into the 1-(2,6-
with 40% yield under
8
Traces
n. d.
n. d.
7
6
standard conditions.[14] Next, the alkylation reaction of the
product 6 using (phenylthio)methyl chloride under elevated
temperature in dry acetonitrile resulted in the formation of the
NHC precursor 7 with high yield (76%). Subsequently, the
construction of sulfur-NHC copper complex 8Cl was successfully
accomplished by the treatment the ligand precursor 7 with
potassium tert-butoxide in the presence of CuCl in THF at room
temperature. The desired complex 8Cl was provided with a good
yield (62%).
9
10
11
12
13
5Cl
5Cl
5Cl
5Cl
15
Toluene
n. d.
[a] Reaction conditions: benzyl bromide S1 (1.0 eq), phenylacetylene S2 (1.2
In case of the synthesis of the unsaturated copper complex
12Cl, the starting material was 2,4,6-trimethylaniline 9, which
was used in the first step to obtain 1-(2,4,6-trimethylphenyl)-1H-
imidazole 10 (Scheme 2).[14],[15] Next, the imidazole derivative 10
was reacted with an excess of (phenylthio)methyl chloride to
give the unsymmetrical salt 11 with 71% yield. In analogy to
previous syntheses, the sulfur-functionalized NHC copper(I)
complex 12Cl was gained in the reaction with KOtBu and
copper(I) chloride. The expected product 12Cl was isolated with
53% yield. The complexes 8Cl and 12Cl were received as white
powders and were fully characterized by spectral techniques.
Moreover, the solid-state structure of the compound 8Cl was
elucidated using X-Ray crystallography analysis with the mixture
of dichloromethane and n-pentane. More details about
crystallographic data of 8Cl can be found in the section on
crystallographic studies (Figure 1 and Figure 2 and Table 5).
To expand more knowledge about properties of the
unsaturated copper analogues with a thioether chain, we next
examined their catalytic performance in three component click
reaction. Obtained results were showed in Table 2.
eq), NaN3 (1.2 eq), solvent (1 mL), 24 h.
Preliminary studies revealed that, obtained copper complexes
with bromine (5Br) and iodine (5I) ions indicated considerably
different activity compared to chlorine analogue (5Cl). Moreover,
it turned out that among tested solvents, methanol was chosen
as the best reaction media. After 24 hours of the conduction of
1,3-dipolar cycloaddition reaction of azides and alkynes in
MeOH, the product P1 was isolated with 73% yield using the
catalyst 5Cl (Table 1, entry 1). Replacement of the anionic
ligand from chlorine to bromine resulted in much lower yield
(48%) of the product P1 (Table 1, entry 2). Finally, the iodo
copper complex (5I) was inactive at applied conditions, probably
due to its low stability (Table 1, entry 3). Other attempts to
improve the catalytic performance of new complexes proved to
be definitely ineffective in examined solvents such as: DCM,
DMSO, EtOAc, THF, toluene and n-hexane (Table 1, entries 4-
13).
Based on the initial activity results of the saturated NHC
copper(I) complexes, we also decided to prepare unsaturated
analogues containing chlorine ions, because the best activity
and stability was observed for the copper compound (5Cl). The
synthetic approach to unsaturated NHC copper(I) complexes
8Cl and 12Cl followed a straightforward strategy similar to the
saturated derivatives (Scheme 2).
Table 2. Effect of solvent and catalyst loading on CuAAC reaction.
Entry
[Cu] cat.
Mol (%)
Solvent
Yield of P1(%)
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10.1002/ejoc.201700523
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activity of new copper catalysts with standard NHC copper
catalytic systems, we also presented examples of some results
from literature in Table 2 (entries 12-14).[5i],[12],[13] As can be
seen, the standard NHC copper complexes were active in the
mixture of polar solvents such as water/t-BuOH and
DMSO/water. In some cases, high temperature and extension of
reaction time were required to activate these catalysts to obtain
the expected product P1 (Table 2, entry 12).
To demonstrate the applicability of the 8Cl catalyst we turned
our attention into three component click reaction (Scheme 3).
Series of varied benzyl bromides and alkynes were subjected to
optimal reaction conditions described above. The final outcomes
were presented in Scheme 3.
1
8Cl
5.0
5.0
5.0
5.0
5.0
5.0
2.0
2.0
1.0
1.0
2.0
2.0
5.0
5.0
MeOH
89[a]
82[a]
41[a]
27[a]
n. d.[a]
74[a]
88[a]
72[a]
80[a]
68[a]
73[a]
98[b]
18[c]
65[c]
2
8Cl
EtOH
3
8Cl
DCM
4
8Cl
DMSO
5
8Cl
THF
6
12Cl
8Cl
MeOH
7
MeOH
8
12Cl
8Cl
MeOH
9
MeOH
10
11
12
13
14
12Cl
5Cl
MeOH
MeOH
SIPrCuCl
IPrCuCl
IMesCuCl
DMSO/Water
Water/t-BuOH
Water/t-BuOH
[a] Reaction conditions: benzyl bromide (1.0 eq), phenylacetylene (1.2 eq),
NaN3 (1.2 eq), solvent (1 mL), rt, 24 h, isolated yields. [b] Reaction conditions:
rt, 1 week, 60º C, 1 h, isolated yield. [c] Reaction conditions: rt, 18 h, isolated
yields.
In analogy to the examination conducted for the saturated
complexes with thioether NHC ligand (5Cl, 5Br and 5I), we first
investigated the effect of various solvents using 5 mol% of
compound 8Cl. It was interesting to note, that the reaction
proceeded well only in MeOH and EtOH (Table 2, entries 1 and
2), however the yield of product P1 in methanol was slightly
higher (89%). Continuing the study, low yields (41% and 27%)
were observed for DCM and DMSO within 24 h (Table 2, entries
3 and 4). Moreover, in case of using THF as the reaction media,
no product P1 was detected (entry 5). When comparing the
activity between unsaturated complexes 8Cl and 12Cl, higher
yield of the product P1 was isolated using the catalyst with 2,6-
diisopropyl substituent (Table 2, entries 1 and 6). After selecting
methanol as the best solvent, next studies were related to find
out the optimal amount of unsaturated complexes for CuAAC
reaction. Decreasing the amount of initiators: 8Cl and 12Cl from
5 mol% to 2 mol% led to obtain 1,4-disubstituted triazole P1 with
constantly high yields (88% and 72% respectively, Table 2,
entries 7 and 8). However, further reduction in application of
catalysts 8Cl and 12Cl to 1 mol% resulted in lower yields of the
product P1 (80% and 68%, Table 2, entries 9 and 10). At this
stage, the optimal conditions to perform three component
CuAAC reaction were designated as: 5 mol% of catalyst 8Cl and
the use of MeOH as the solvent of choice. To confirm eventually,
which copper initiator bearing the thioether chain is the best
performer for this transformation, we carried out one more
control experiment to compare the reactivity of 8Cl and 5Cl. It
turned out that using the unsaturated analogue with 2,6-
diisopropyl substituent 8Cl, the highest yield of 1,4-disubstituted
triazole P1 (89%, Table 2, entry 1) was determined, than the
initiator 5Cl (73%, Table 2, entry 11). In order to compare
Scheme 3. Three component synthesis of various substituted triazoles
catalyzed by 8Cl.
As shown, applied terminal alkynes and benzyl bromides in
the presence of sodium azide can be transformed to the
corresponding triazoles using the complex 8Cl with good to high
yields after 2 hours. In most cases, we isolated 1,4-disubstituted
1,2,3-triazoles as the only products (Scheme 3). These
compounds P1-P6 containing non-substituted and electron
donating groups were obtained with very good yields (65-94%)
(Scheme 3).
In contrary to these examples, for reactions of starting
materials bearing electron withdrawing groups, we were
surprised to observe exclusively the formation of 1,4,5-
trisubstituted 1,2,3-triazoles P7-P8 with high yields (78-90%).
This observation might be the result of consecutive reactions:
Glaser coupling and 1,3-dipolar cycloaddition. Such
regioselective formation of different substituted 1,4,5-
trisubstituted 1,2,3-triazoles was previously reported by Gerard
et al.[16] The same outcome can be also explained by the fact
that the complex 8Cl may activate the 5-position in 1,4-
disubstituted 1H-1,2,3-triazole, such as it has been shown in the
]
publication by F. Alonso et al.[17
To gain more information about activity of obtained copper
complexes, we investigated their properties in another three
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component transformation known as A3 coupling reaction.
Products of this multicomponent one-pot synthesis are suitable
synthetic building blocks of amino derivatives.[18],[19],[20] In order to
identify the best performing copper catalyst containing sulfur
moiety, the model reaction was carried out including
product P9 in 91% and 76% yields, respectively. In Table 3, we
also placed outcomes for the model A3 coupling reaction, when
standard NHC copper catalytic systems were applied. As can be
seen from entries 13-15, the saturated complex SIPrCuCl was
able to promote A3 coupling reaction similarly well as the
complex 8Cl (90%), whereas unsaturated analogue IPrCuCl
gave lower yield (79%). The complex IMesCuCl failed as the
suitable catalyst of this transformation (yield 8%).
phenylacetylene
cyclohexenecarboxaldehyde as starting materials (Table 3).
and
N,N-dimethylamine
with
With the optimized conditions in hand for A3 coupling reaction,
the scope containing various propargylamines was presented on
Scheme 4.
Table 3. Effects of solvent and catalysts loading on A3 coupling reaction.
Entry
1
[Cu] cat.
8Cl
(mol %)
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
0.5
0.2
0.5
0.5
0.5
Solvent
DCM
Yield of P9(%)[a]
Traces
Traces
Traces
n. d.
89
2
8Cl
n-hexane
Toluene
DMSO
MeOH
MeOH
MeOH
THF
3
8Cl
4
8Cl
5
8Cl
6
5Cl
70
7
12Cl
8Cl
81
8
28
Scheme 4. Three component synthesis of substituted propargylamines
catalyzed by 8Cl.
9
5Cl
THF
5
As displayed on Scheme 4, the complex 8Cl promoted A3
coupling reaction smoothly in methanol, giving high yields for all
six products P9-P14 (84-92%). Using only 0.5 mol % of 8Cl,
electron-rich and electron-deficient alkynes were transformed
into desired propargylamines in very short time (20 minutes) at
room temperature. We also carried out some additional
experiments of A3 coupling reaction, when different
benzaldehydes were used as substrates. Unfortunately, similarly
to Wang and Navarro’s studies, significant decrease in reactivity
was observed, even in higher reaction temperatures (60º C) and
extension of reaction time (3 days).[19] No expected products
were identified in these reactions.
10
11
12
13
14
15
12Cl
8Cl
THF
16
MeOH
MeOH
MeOH
MeOH
MeOH
91
8Cl
76
SIPrCuCl
IPrCuCl
IMesCuCl
90
79
8
[a] Reaction conditions: phenylacetylene (1.1 eq), N,N-dimethylamine (1.1 eq),
cyclohexenecarboxaldehyde (1.0 eq), solvent (1 mL), 20 min, isolated yields.
In a survey of catalytic activity of obtained copper complexes
bearing a thioether chain, we also employed hydroboration
reaction of triple and double bonds. Based on efficient
methodology presented by Cazin’s group, we followed their
general conditions in our experiments (Table 4).[21]
The examination of optimal conditions for the synthesis of the
propargylamine P9 was held in the presence of three copper
complexes: 5Cl, 8Cl and 12Cl. Among tested solvents,
methanol proved to be the most convenient reaction medium
(Table 3, entries 1-10). The A3 coupling reactions that were
proceeded in DCM, DMSO, n-hexane and toluene have shown
no formation of the expected product P9 (Table 3, entries 1-4).
Results of the reactions carried out in THF were also
unsatisfactory (5-28%) (Table 3, entries 8-10). Finally, this
search revealed that the initiator 8Cl has been promoted studied
transformation in the most efficient way to give the product P9
with 91% yield (Table 3, entry 11). Subsequently, we
investigated also the most suitable loading of the catalyst (Table
3, entries 11-12). For this propose, we conducted two more
experiments using 0.5 mol% and 0.2 mol% of the complex 8Cl.
In both cases, these reactions proceeded smoothly to give the
Table 4. Study of NHC copper complexes in hydroboration reaction.
Entry
[Cu] cat.
Solvent
Yield of P15(%)
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complex containing sulfur moiety 8Cl similar to well-known
copper NHC catalytic systems.
1
2
3
4
5
5Cl
CPME
CPME
CPME
i-PrOH
CPME
93[a]
97[a]
96[a]
34[b]
98[c]
8Cl
CRYSTALLOGRAPHIC STUDIES
12Cl
Investigated copper compounds form monoclinic crystals in
Cc (8Cl) or P21/c (5Cl and 5Br) space group with one molecule
in the asymmetric unit of the crystal lattice (Figure 1 and Figure
2). The crystallographic data and selected bond lengths and
valence angles are presented in Table 5.
IPrCuCl
IMesCuCl
[a] Reaction conditions: [Cu] cat. (0.05 mol%), B2(pin)2 (1.1 eq), NaOH (1
mol%), MeOH (0.1 mL), CPME (1 mL), 18 h, isolated yields, only β isomer was
detected. [b] Reaction conditions: [Cu] cat. (0.04 mol%), B2(pin)2 (1.1 eq),
NaOt-Bu (1 mol%), MeOH (0.18 mL), i-PrOH (2.4 mL), 16 h, isolated yields. [c]
Reaction conditions: [Cu] cat. (0.04 mol%), B2(pin)2 (1.1 eq), NaOH (5 mol%),
MeOH (0.05 mL), CPME (0.6 mL), 16 h, isolated yield.
For the evaluation step as representative substrate, we used
1-phenyl-1-butyne as the benchmark substrate. At 0.05 mol%
catalysts loading, we compared the three NHC copper catalyst
containing sulfur moiety (5Cl, 8Cl and 12Cl) with activity data
from literature for well-known copper systems (IPrCuCl and
IMesCuCl) (Table 4).[21] As shown, in most cases, the product
P15 was formed in very good yields (93-98%) and with high
regioselectivity. Only one exception was revealed in entry 4,
when Cazin’s group used i-PrOH as the reaction media (34%
yield).[21] The β-hydroboration reaction proceeded well in air
using the green solvent CPME and 1 mol% of NaOH. These
mild conditions were applied for further examination. All novel
examples of NHC copper(I) complexes with a thioether ligand
were very efficient in hydroboration reaction, however the
highest performance was noticed for initiator 8Cl (Table 4, entry
2).
Based on the initial results presented in Table 4, we
continued the scope of hydroboration using few examples of
alkynes and alkenes (Scheme 5).
Scheme 5. Hydroboration reaction of alkynes and alkenes catalyzed by 8Cl.
Figure 1. The molecular structure of 5Cl, 5Br and 8Cl – showing the atom
labelling scheme. Displacement ellipsoids are drawn at the 25% probability
level and H-atoms are shown as small spheres of arbitrary radius. The
hydrogen bonds and Cu···π interactions are respectively represented by
dashed and dotted lines. Cg2 represents the centre of gravity of the C10–C15
aromatic ring.
This methodology gave good outcomes in the presence of
various groups including phenyl (P15, 97%), naphthyl (P17,
97%), heterocyclic (P16, 95%), electron donating substituent
(P18, 94%) and electron withdrawing substituent (P19, 96%)
(Scheme 5). Furthermore, the compounds P15 and P16 were
isolated as the only isomers, what emphasizes good
regioselectivity and high functionality tolerance of NHC copper
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Conclusions
In summary, we have presented an easily-prepared and
active copper catalytic systems containing a thioether chain. The
preparation of novel family of NHC copper analogues was
consisted of three to four steps and used readily available
reagents. This class of sulfur-functionalized non-symmetrical
copper(I) NHC complexes were fully characterized and tested in
three various transformations. X-Ray measurements revealed
typical bond lengths and valence angles for standard (NHC)CuX
systems. Moreover, in the structure of copper analogue 8Cl was
observed additional interaction involving two intra molecular C–
H···N hydrogen bonds. Based on activity examinations,
unsaturated complex 8Cl with
a
2,6-diisopropylphenyl
substituent displayed the best catalytic performance in three
component click reaction, A3 coupling and hydroboration in air.
This copper complex proved to be an efficient catalyst with
enhanced stability properties and a good activity profile. Further
research on NHC copper complexes bearing sulfur moiety will
be demonstrated and reported in due course.
Figure 2. Structural alignment of 5Cl, 5Br and 8Cl (hydrogen atoms were
omitted for clarity).
All three complexes have two-coordinated copper(I) center in
a near linear environment. The value of C–Cu–X angle lies in
the range of 175.7(2)–176.6(1)º. The C–Cu and Cu–X bond
lengths are ranging 1.883(2)–1.893(6) and 2.098(2)–2.216(1) Å,
respectively (Table 5). Above-mentioned values quite well
correspond with those observed in similar (NHC)CuX
systems.[12],[13]
Compounds 5Cl and 5Br are isostructural, whereas 8Cl
indicates observable change of the ligand geometry. This
phenomenon is caused by the appearing of a double bond in the
NHC backbone ring, which is manifested by increasing of the
angles between mean-square planes delineated by the non-
hydrogen atoms of phenyl rings and NHC backbone (Figure 1).
In case of 5Cl and 5Br planes of respective phenyl rings are
inclined to the NHC backbone by the angles of approximately
77º (ring 1) and 55º (ring 2).
In 8Cl both phenyl rings are more twisted – respective angles
for ring 1 and 2 are ca. 88º and 64º. The above-described
mutual arrangement has an impact on the occurrence of
intramolecular interactions. In case of 8Cl the structure is
stabilized by two intramolecular C–H···N hydrogen bonds,
whereas in 5Cl and 5Br there is only one interaction of this type.
However specific substituent arrangement in 5Cl and 5Br
promotes appearance of the Cu··· π interaction, which is not
observed in 8Cl (Figure 2).
Experimental Section
The procedure for the preparation of compound 2: In the flask, to
the solution of 2,6-diisopropylaniline 1 (20 mL, 0.11 mol) in toluene (20
mL) was added 2-bromoethylamine hydrobromide. The reaction mixture
was refluxed at 100 °C for 48 hours. After the completion of reaction,
the mixture was cooled to rt and poured into a solution of 2M KOH (100
mL). The residue was extracted with Et2O (2 x 80 mL), and then dried
over anhydrous MgSO4. After concentration by evaporation the
resulting compound 2 was purified by column chromatography. The
product 2 was obtained as dark-brown oil in 40% yield (18.9 g). 1H
NMR (400 MHz, CDCl3): δ 7.12–7.01 (m, 3H), 3.37–3.24 (m, 2H), 2.99–
2.89 (m, 4H), 1.30–1.19 (m, 12H) ppm; 13C NMR (101 MHz, CDCl3) δ
142.5, 123.7, 123.5, 54.1, 42.5, 27.6, 24.3, 24.3 ppm. Spectroscopic
data for the compound 2 were consistent with the previously reported
ones.[9]
The procedure for the preparation of compound 3: An argon flushed
flask was charged with the appropriate diamine 2 (10 g; 45 mmol) and
triethyl orthoformate (28 mL, 167 mmol) and p-toluenesulfonic acid
(0.16 g). The reaction was carried out at 130 °C under argon
atmosphere and monitored by TLC (dichloromethane/methanol, v/v =
20:1). After completion of the reaction, the mixture was cooled,
dissolved in water (50 mL) and extracted with Et2O (2 x 35 mL). The
combined organic phases were dried over anhydrous magnesium
sulfate and the solvent was evaporated under the reduced pressure.
The resulting compound 3 was purified by column chromatography
using dichloromethane/methanol (v/v = 20:1) as eluent to give the
brown solid in 81% yield (7.9 g). 1H NMR (400 MHz, CDCl3): δ 7.31 (dd,
J = 8.2, 7.2 Hz, 1H), 7.19 (dd, J = 15.6, 7.7 Hz, 2H), 6.96 (s, 1H), 4.08
(t, J = 10.4, 1.6 Hz, 2H), 3.66–3.57 (m, 2H), 3.13–2.98 (m, 2H), 1.30–
1.08 (m, 12H) ppm; 13C{1H} NMR (101 MHz, CDCl3): δ 148.2, 128.9,
128.7, 125.9, 124.7, 124.2, 51.7, 28.4, 28.2, 24.9, 24.1 ppm.
Spectroscopic data for the compound 2 were consistent with the
previously reported ones.[21]
Table 5. Selected bond lengths and angles of 5Cl, 5Br and 8Cl.
5Cl
5Br
8Cl
Cu6-X7 [Å]
Cu6-C1 [Å]
C1-N2 [Å]
2.105(4)
1.883(2)
1.340(2)
1.441(2)
1.826(1)
1.343(2)
1.439(2)
1.530(2)
108.1(1)
125.1(9)
100.4(6)
176.6(1)
2.216(1)
1.885(2)
1.341(3)
1.444(3)
1.829(2)
1.344(3)
1.442(3)
1.530(3)
108.1(2)
127.1(2)
100.4(1)
176.1(7)
2.098(2)
1.893(6)
1.349(7)
1.460(7)
1.801(5)
1.347(6)
1.438(7)
1.355(9)
105.4(4)
126.3(4)
101.0(3)
175.7(2)
N2-C8 [Å]
C8-S9 [Å]
C1-N5 [Å]
N5-C16 [Å]
C3-C4 [Å]
N2-C1-N5 [°]
Cu6-C1-N2 [°]
C10-S9-C8 [°]
C1-Cu-X7 [°]
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10.1002/ejoc.201700523
European Journal of Organic Chemistry
FULL PAPER
(dd, J = 11.7, 6.8 Hz, 12H) ppm; 13C{1H} NMR (101 MHz, CD2Cl2): δ
159.4, 146.3, 131.8, 131.0, 130.5, 129.7, 129.5, 128.3, 124.8, 52.9,
51.5, 28.6, 24.7, 23.9 ppm; HRMS-ESI (m/z) calcd for C22H28N2S [M–
H–Cl]+: 353.2046, found 353.2045; IR (diamond tip): ν 2963, 1673,
1620, 1440, 1345, 1265, 805, 745, 479, 421 cm-1.
The procedure for the preparation of compound 6: 2,6-
Diisopropylaniline 1 (8.9 g, 9.4 mL, 50 mmol) and 30% glyoxal (8 mL)
were stirred in methanol (45 mL) at room temperature, for 24 h. Next,
ammonium chloride (5.4 g), 37% solution of formaldehyde (8 mL) and
methanol (200 mL) were added the reaction mixture and refluxed for 1
h. Subsequently, a solution of 85% H3PO4 (7 mL) was added the
reaction mixture and refluxed for another 1 h. The reaction was
monitored by TLC (n-hexane/ethyl acetate, v/v = 1:1). After completion
of reaction the solvent was evaporated. The reaction mixture was
poured into 300 g of crushed ice and 40% solution of KOH was
gradually added until the pH = 9. The resulting mixture was extracted
with Et2O (5 x 75 mL). The collected organic layers were dried over
anhydrous MgSO4. After concentration by evaporated under the
reduced pressure, the crude product was purified by column
chromatography (n-hexane/ethyl acetate, v/v = 1:1). The product 6 was
obtained as a dark brown solid in 40% yield (4.55 g). 1H NMR (400
MHz, CDCl3): δ 7.49–7.36 (m, 2H), 7.28–7.14 (m, 3H), 3.44 (s, 1H),
2.45–2.32 (m, 2H), 1.11 (d, J = 6.9 Hz, 12H) ppm; 13C{1H} NMR (101
MHz, CDCl3): δ 146.5, 129.8, 129.4, 123.7, 122.8, 28.1, 24.4, 24.3 ppm.
Spectroscopic data for the compound 6 were consistent with the
previously reported ones.[22]
The procedure for the preparation of compound 7: A 25 mL flask,
was charged with compound 6 (2 g, 0.0087 mol) and chloromethyl
phenyl sulfide (1.45 g; 1.2 mL; 0.009 mol) then dry DMF (6 mL) was
added. The reaction was carried out at 100 °C under an inert
atmosphere
The
reaction
was
monitored
by
TLC
(dichloromethane/methanol v/v = 9:1). After completion of reaction the
solvent was evaporated, the resulting compound 7 was purified by
column chromatography (dichloromethane/methanol, v/v = 9:1). Then
crystallisation was carried out with dichloromethane/n-pentane. The
product was obtained as a dark brown solid in 76% yield (2.65 g). 1H
NMR (400 MHz, CDCl3): δ 10.48 (s, 1H), 7.88 (br, 1H), 7.70–7.65 (m,
2H), 7.50–7.40 (m, 1H), 7.38–7.27 (m, 3H), 7.25–7.18 (m, 2H), 6.39 (s,
2H), 1.96 (dd, J = 13.5, 6.8 Hz, 2H), 1.05 (dd, J = 25.7, 6.8 Hz, 12H)
ppm; 13C{1H} NMR (101 MHz, CDCl3): δ 145.2, 139.0, 132.0, 131.8,
129.9, 129.7, 129.6, 128.7, 124.6, 124.0, 122.0, 52.8, 28.5, 24.3, 24.1
ppm; HRMS-ESI (m/z) calcd for C22H26N2S [M–H–Cl]+: 351.1889, found
351.1888; IR (diamond tip): ν 2964, 2868, 1669, 1544, 1459, 1438,
1386, 1365, 1294, 1178, 1112, 1064, 1025, 930, 810, 748, 691, 672,
633, 558, 493, 461 cm-1. M. p. = 185.6 °C
The procedure for the preparation of compound 10: 2,4,6-
trimethylaniline 9 (6.8 g, 7.0 mL, 50 mmol) and 30% glyoxal (8.1 mL)
were placed into a round bottom flask and were stirred in methanol (30
mL) at room temperature for 24 h. Next, ammonium chloride (5.4 g), 37%
solution of formaldehyde (8 mL) and methanol (200 mL) were
transferred to the flask and refluxed for 1 h. After this time, 85%
solution of H3PO4 (7 mL) was added to the reaction mixture and was
refluxed for another 1 h. The reaction was monitored by TLC (n-
hexane/ethyl acetate, v/v = 1:1). After completion of reaction the
solvent was evaporated. The reaction mixture was poured into 300 g of
crushed ice and 40% solution of KOH was gradually added until the pH
= 9. The resulting mixture was extracted with Et2O (5 x 75 mL). The
collected organic layers were dried over anhydrous MgSO4. After
concentration by evaporated under the reduced pressure the crude
product was purified by column chromatography (n-hexane/ethyl
The procedure for the preparation of compound 11: A Schlenk flask
was charged with compound 10 (2 g, 0.0087 mol) and chloromethyl
phenyl sulfide (1.45 g; 1.2 mL; 0.009 mol). Next, dry DMF (6 mL) was
added to the reaction mixture. The reaction was carried out at 100 °C
under an argon atmosphere and was monitored by TLC
(dichloromethane/methanol v/v = 9:1). After completion of reaction the
solvent was evaporated and the resulting compound 11 was purified by
column chromatography (dichloromethane/methanol, v/v = 9:1). Then,
crystallisation was carried out with dichloromethane/n-pentane. The
product was obtained as a yellow solid in 71% yield (2.67 g). 1H NMR
(400 MHz, CDCl3): δ 10.33 (s, 1H), 7.81–7.79 (m, 1H), 7.60–7.55 lub
7.57 (dd, J = 8.2, 1.4 Hz, 2H), 7.34–7.20 (m, 4H), 7.05 (s, 2H), 6.88 (d,
J = 0.5 Hz, 2H), 6.29 (s, 2H), 2.26 (s, 2H), 1.79 (s, 6H) ppm; 13C{1H}
NMR (101 MHz, CDCl3): δ 141.3, 138.7, 134.1, 132.5, 130.4, 129.8,
129.7, 128.2, 123.1, 122.05, 53.0, 21.0, 17.3 ppm; HRMS-ESI (m/z)
calcd for C19H20N2S [M–H–Cl]+: 309.1420, found 309.1427; IR
(diamond tip): ν 2970, 2919, 1557, 1544, 1482, 1438, 1199, 1159, 1103,
1066, 1023, 890, 859, 766, 745, 693, 670, 627, 580, 555, 485, 444 cm-1.
M. p. = 182–185 °C
1
acetate, v/v = 1:1) to give yellow solid (65%, 6.0 g). H NMR (400 MHz,
CDCl3): δ 7.42 (t, J = 1.0 Hz, 1H), 7.22 (t, J = 1.1 Hz, 1H), 7.00–6.92 (m,
2H), 6.88 (t, J = 1.2 Hz, 1H), 2.33 (s, 3H), 1.98 (s, 6H) ppm; 13C{1H}
NMR (101 MHz, CDCl3): δ 138.8, 137.5, 135.4, 133.4, 129.5, 128.9,
120.0, 28.1, 21.0, 17.3 ppm. Spectroscopic data for the compound 10
were consistent with the previously reported ones.[23],[24]
The procedure for the preparation of copper complex 5Cl: A dry
and argon flushed a Schlenk flask was charged with copper(I) chloride
The procedure for the preparation of compound 4: To the solution
of compound 3 (0.7 g, 3 mmol) in dry DMF (4 mL), chloromethyl phenyl
sulfide (0.5 g, 0.4 mL, 3.2 mmol) was slowly added at room
temperature. The reaction was conducted at 100 °C under an inert
atmosphere and was monitored by TLC (dichloromethane/methanol, v/v
= 9:1). After completion of the reaction, the solvent was evaporated and
the resulting compound 4 was purified by column chromatography
(dichloromethane/methanol, v/v = 9:1). The product 4 was obtained as
a dark brown oil which slowly crystallized at low temperature (5 °C) in
75% yield (0.85 g). 1H NMR (400 MHz, CDCl3): δ 9.82 (s, 1H), 7.73–
7.68 (m, 2H), 7.40–7.28 (m, 4H), 7.14 (d, J = 7.8 Hz, 2H), 5.75 (s, 2H),
4.32 (d, J = 11.6 Hz, 2H), 4.03 (d, J = 11.6 Hz, 2H), 2.51 (m, 2H), 1.13
(0.14
g;
1.4
mmol),
1-(2,6-diisopropylphenyl)-3-
((phenylthio)methyl)imidazolinium chloride 4 (0.5 g; 1.3 mmol), and
potassium tert-butoxide (0.15 g; 1.4 mmol), then was added dry THF
(20 mL). The mixture was stirred for 20 h at room temperature under an
inert atmosphere of argon. The reaction was monitored by TLC (n-
hexane/ethyl acetate, v/v = 1:1 and 7:3). After completion of reaction
the solvent was evaporated. The crude product was purified by column
chromatography (n-hexane/ethyl acetate, v/v
=
1:1). Then
crystallization from dichloromethane/n-pentane was carried out to give
the complex 5Cl as an white solid in 73% yield (0.43 g). 1H NMR (400
MHz, CDCl3): δ 7.61–7.56 (m, 2H), 7.43–7.26 (m, 4H), 7.11 (m, 2H),
5.17 (s, 2H), 3.97–3.88 (m, 2H), 3.77–3.67 (m, 2H), 2.62–2.49 (m, 2H),
1.13 (dd, J = 10.6, 6.9 Hz, 12H) ppm; 13C{1H} NMR (101 MHz, CDCl3):
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10.1002/ejoc.201700523
European Journal of Organic Chemistry
FULL PAPER
δ 146.4, 134.0, 133.2, 130.7, 129.8, 129.7, 128.6, 124.5, 56.0, 54.0,
46.5, 28.2, 25.3, 24.2 ppm; HRMS-ESI (m/z) calcd for C22H28N2SCu
[M–H–Cl]+: 415.1264, found 415.1251; IR (diamond tip): ν 2951, 2921,
2862, 1674, 1584, 1484, 1471, 1447, 1411, 1383, 1362, 1340, 1315,
1265, 1238, 1216, 1184, 1099, 1056, 1023, 935, 906, 888, 847, 806,
765, 751, 704, 695, 647, 613, 594, 560, 527, 493, 466 cm-1.
7.59–7.05 (m, 10H), 6.85 (d, J = 1.8 Hz, 1H), 5.57 (s, 2H), 2.20–2.00
(m, 2H), 1.07 (dd, J = 28.8, 6.9 Hz, 12H) ppm; 13C{1H} NMR (101 MHz,
CDCl3): δ 145.5, 134.1, 133.2, 130.4, 130.0, 129.6, 129.0, 124.3, 124.1,
119.6, 55.4, 28.1, 24.5, 24.2 ppm; HRMS-ESI (m/z) calcd for
C22H26N2SCu [M–H–Cl]+: 413.1107, found 413.1112; IR (diamond tip):
ν 2965, 1459, 1405, 1284, 1245, 1221, 1177, 1057, 810, 769, 748, 707,
692, 491 cm-1.
The procedure for the preparation of copper complex 8Cl: In a dry
and argon flushed a Schlenk flask were placed copper(I) bromide
The procedure for the preparation of copper complex 12Cl: Under
an atmosphere of argon imidazolium salt 11 (0.5 g; 1.45 mmol) and
potassium tert-butoxide (0.17 g; 1.52 mmol) were dissolved dry THF
(20 mL). Next, copper(I) chloride (0.15 g; 1.52 mmol) was added to the
reaction. The mixture was stirred for 20 h at room temperature under an
atmosphere of argon. The reaction was monitored by TLC (n-
hexane/ethyl acetate, v/v = 7:3). After completion of reaction the
solvent was evaporated. The crude product was purified by column
(0.059
g;
0.41
mmol),
1-(2,6-diisopropylphenyl)-3-
((phenylthio)methyl)imidazolinium chloride 4 (0.15 g; 0.39 mmol), and
potassium tert-butoxide (0.046 g; 0.41 mmol). To these was added dry
THF (6 mL). The mixture was stirred for 20 h at room temperature
under an inert atmosphere of argon. The reaction was monitored by
TLC (n-hexane/ethyl acetate, v/v = 1:1 and 7:3). After completion of
reaction the solvent was evaporated. The crude product was purified by
column chromatography (n-hexane/ethyl acetate, v/v = 1:1). Then was
carried out crystallization from dichloromethane/n-pentane to give the
complex 5Br as an off-white solid in 52% yield (0.1 g). 1H NMR (400
MHz, CDCl3): δ 7.55–7.47 (m, 2H), 7.31–7.23 (m, 3H), 7.19 (ddd, J =
8.5, 6.4, 1.8 Hz, 1H), 7.13 (d, J = 7.7 Hz, 2H), 4.90 (s, 2H), 3.69–3.61
(m, 2H), 3.58–3.49 (m, 2H), 2.79 (dt, J = 13.7, 6.9 Hz, 2 H), 1.14 (dd, J
= 13.6, 6.9 Hz, 12H) ppm; 13C{1H} NMR (101 MHz, CDCl3): δ 146.4,
133.9, 133.2, 130.6, 129.8, 129.7, 128.6, 124.5, 55.9, 54.0, 46.5, 28.2,
25.3, 24.2 ppm; HRMS-ESI (m/z) calcd for C22H28N2SCu [M–H–Br]+:
415.1264, found 415.1273; IR (diamond tip): ν 2920, 1677, 1580, 1485,
1473, 1449, 1381, 1360, 1313, 1264, 1236, 1215, 1188, 1095, 1055,
1021, 932, 901 , 843, 805, 762, 753, 695, 648, 594, 561, 528 cm-1.
chromatography (n-hexane/ethyl acetate, v/v
=
7:3). Then
crystallization was carried out using mixture of solvents:
dichloromethane/n-pentane to give the complex 12Cl as a white solid in
53% yield (0.32 g). 1H NMR (400 MHz, CDCl3): δ 7.85–7.15 (m, 5H),
6.88 (s, 2H), 5.57 (s, 2H), 6.40 (bs, 1H), 6.08 (bs, 1H), 5.52 (bs, 1H),
5.08 (bs, 1H), 2.27 (bs, 3H), 2.10–1.55 (m, 6H) ppm; 13C{1H} NMR
(101 MHz, CDCl3): δ 151.5, 133.6, 131.7, 129.7, 129.6, 129.3, 129.1,
129.0, 121.1, 109.9, 47.0, 21.0, 17.8, 17.6 ppm; IR (diamond tip): ν
2916, 2848, 1685, 1486, 1472, 1438, 1405, 1233, 1213, 1022, 851, 741,
729, 710, 692, 656, 584, 489, 480 cm-1.
Typical procedure for the three component CuAAC reaction:
Organic halide (0.013 mmol, 1.0 eq), NaN3 (1.2 mmol), alkyne (0.16
mmol, 1.2 eq.), the appropriate copper complex (5 mol%) and solvent
(1 mL) were introduced to the vial fitted with a screw cap. The reaction
was carried out at room temperature for 2 h and controlled by TLC (n-
hexane/ethyl acetate, v/v = 7:3). After completion of the reaction, the
solvent was evaporated. The crude product was purified by column
The procedure for the preparation of copper complex 5I: In a dry
and argon flushed a Schlenk flask were placed copper(I) iodine (0.077
g;
0.41
mmol),
1-(2,6-diisopropylphenyl)-3-
((phenylthio)methyl)imidazolinium chloride 4 (0.15 g; 0.39 mmol), and
potassium tert-butoxide (0.045 g; 0.41 mmol). To these was added dry
THF (6 mL). The mixture was stirred for 20 h at room temperature
under an inert atmosphere of argon. The reaction was monitored by
TLC (n-hexane/ethyl acetate, v/v = 1:1 and 7:3). After completion of
reaction the solvent was evaporated. The crude product was purified by
column chromatography (n-hexane/ethyl acetate, v/v = 1:1). Then, the
crystallization was carried out using dichloromethane/n-pentane as
solvents to give the complex 5I as a yellowish solid in 38% yield (0.074
g). 1H NMR (400 MHz, CDCl3): δ 7.57–7.46 (m, 2H), 7.32–7.23 (m, 3H),
7.22–7.16 (m, 2H), 7.13 (d, J = 7.7 Hz, 2H), 4.90 (s, 2H), 3.70–3.60 (m,
2H), 3.58–3.48 (m, 2H), 2.79 (dt, J = 13.7, 6.9 Hz, 2H), 1.14 (dd, J =
13.6, 6.9 Hz, 12H) ppm; 13C{1H} NMR (101 MHz, CDCl3): δ 148.0,
134.1, 133.0, 130.5, 129.0, 128.7, 126.7, 124.0, 49.3, 46.0, 41.2, 28.4,
24.5, 24.2 ppm; IR (diamond tip): ν 2950, 2918, 2855, 1673, 1584,
1485, 1473, 1445, 1342, 1310, 1263, 1236, 1215, 1182, 1054, 935, 886,
848, 801, 764, 746, 695, 667, 614, 550, 515, 465 cm-1.
chromatography (n-hexane/ethyl acetate, v/v
= 8:2). The isolated
product was dried under vacuum.
1-benzyl-4-phenyl-1H-1,2,3-triazole, P1, white solid, yield 89%;
1H NMR (400 MHz, CDCl3): δ 7.83–7.75 (m, 2H), 7.65 (s, 1H), 7.46–
7.34 (m, 5H), 7.33–7.27 (m, 3H), 5.57 (s, 2H) ppm; 13C{1H} NMR (101
MHz, CDCl3): δ 148.2, 134.6, 130.5, 129.1, 128.8, 128.1, 125.7, 119.4,
54.2 ppm. Spectroscopic data for the compound P1 were consistent
with the previously reported ones.[25]
1-benzyl-4-cyclohexyl-1H-1,2,3-triazole, P2, light-yellow solid, yield
80%; 1H NMR (400 MHz, CDCl3): δ 7.41–7.28 (m, 3H), 7.26–7.22 (m,
2H), 7.13 (s, 1H), 5.47 (s, 2H), 2.72 (m, 1H), 2.05–1.97 (m, 2H), 1.81–
1.64 (m, 3H), 1.43–1.28 (m, 4H), 1.26–1.15 (m, 1H) ppm; 13C{1H} NMR
(101 MHz, CDCl3): δ 154.2, 135.0, 128.5, 128.0, 119.1, 54.0, 35.3, 33.0,
26.1 ppm. Spectroscopic data for the compound P2 were consistent
with the previously reported ones.[26]
The procedure for the preparation of copper complex 5Br: In dry
and argon flushed Schlenk flask were placed copper(I) chloride (0.14 g;
1.4 mmol), ligand precursor 7 (0.5 g; 1.3 mmol), potassium tert-
butoxide (0.16 g; 1.4 mmol). All reagents were dissolved in dry THF (20
mL). The mixture was stirred for 20 h at room temperature under argon
atmosphere. The reaction was monitored by TLC (n-hexane/ethyl
acetate, v/v = 7:3). After completion of the reaction the solvent was
evaporated. The crude product was purified by column chromatography
(n-hexane/ethyl acetate, v/v = 7:3). Subsequently, the crystallization
from dichloromethane/n-pentane was carried out to give the complex
8Cl as a white solid in 62% yield (0.38 g). 1H NMR (400 MHz, CDCl3): δ
1-(2-iodobenzyl)-4-phenyl-1H-1,2,3-triazole, P3, light-yellow solid, yield
65%; 1H NMR (400 MHz, CDCl3): δ 7.89 (dd, J = 7.9, 1.2 Hz, 1H),
7.84–7.78 (m, 2H), 7.76 (s, 1H), 7.43–7.37 (m, 2H), 7.36–7.28 (m, 2H),
7.12 (dd, J = 7.8, 1.6 Hz, 1H), 7.08–7.02 (m, 1H), 5.66 (s, 2H) ppm;
13C{1H} NMR (101 MHz, CDCl3): δ 148.1, 139.9, 137.4, 130.4, 129.6,
129.1, 128.8, 128.2, 125.7, 119.8, 98.6, 58.5 ppm. Spectroscopic data
for the compound P3 were consistent with the previously reported
ones.[27]
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700523
European Journal of Organic Chemistry
FULL PAPER
4-phenyl-1-(2-(thiophen-2-yl)ethan-2-on-1-yl)-1H-1,2,3-triazole,
P4,
1.96 (m, 1H), 1.80–1.71 (m, 2H), 1.70–1.63 (m, 1H), 1.54 (ddd, J =
14.5, 11.0, 6.1 Hz, 2H), 1.29–1.16 (m, 2H), 0.99 (ddd, J = 24.0, 11.9,
3.2 Hz, 2H) ppm; 13C{1H} NMR (101 MHz, CDCl3): δ 131.7, 128.2,
127.7, 123.6, 86.5, 64.2, 41.6, 40.1, 31.1, 30.3, 26.7, 26.1 ppm; HRMS-
ESI (m/z) [M+H]+ calcd for C17H23N [M+H]+: 242.1903, found 242.1907;
IR (diamond tip): ν 2921, 2850, 2822, 2779, 1488, 1448, 1338, 1316,
1276, 1259, 1224, 1177, 1157, 1121, 1086, 1069, 1044, 1023, 982, 941,
911, 890, 850, 824, 753, 689, 600, 529, 488 cm-1.
yellow solid, yield 88%; 1H NMR (400 MHz, CDCl3): δ 7.96 (s, 1H),
7.89–7.83 (m, 3H), 7.79 (dd, J = 5.0, 1.1 Hz, 1H), 7.45–7.40 (m, 2H),
7.34 (d, J = 7.5 Hz, 1H), 7.22 (dd, J = 5.0, 3.9 Hz, 1H), 5.78 (s, 2H)
ppm; 13C{1H} NMR (101 MHz, CDCl3): δ 183.2, 146.7, 135.9, 133.2,
131.0, 128.8 (d, J = 7.2 Hz), 128.3, 125.8, 121.2, 119.8, 104.1, 55.4
ppm. Spectroscopic data for the compound P4 were consistent with the
previously reported ones.[28]
1-(4-methylbenzyl)-4-phenyl-1H-1,2,3-triazole, P5, yellow solid, yield
93%; 1H NMR (400 MHz, CDCl3): δ 7.82–7.74 (m, 2H), 7.62 (s, 1H),
7.38 (ddd, J = 6.4, 1.3 Hz, 2H), 7.30 (d, J = 7.3 Hz, 1H), 7.22–7.15 (m,
4H), 5.51 (s, 2H), 2.35 (s, 3H) ppm; 13C{1H} NMR (101 MHz, CDCl3): δ
148.1, 138.7, 131.6, 130.6, 129.8, 128.8, 128.1, 125.7, 119.4, 54.0,
21.2 ppm.Spectroscopic data for the compound P5 were consistent
with the previously reported ones.[29]
(1-cyclohexyl-3-(4-fluorophenyl)-N,N-dimethyl-2-yn-1-amine, P10, light-
yellow oil, yield 86%; 1H NMR (400 MHz, CDCl3): δ 7.43–7.37 (m, 2H),
7.01–6.94 (m, 2H), 3.13 (d, J = 10.0 Hz, 1H), 2.27 (s, 6H), 2.07 (dd, J =
8.0, 6.5 Hz, 1H), 1.98 (dd, J = 8.2, 6.6 Hz, 1H), 1.78–1.70 (m, 2H),
1.69–1.61 (m, 2H), 1.52 (dd, J = 10.1, 3.5 Hz, 1H), 1.29–1.15 (m, 3H),
1.06–0.89 (m, 2H) ppm; 13C{1H} NMR (101 MHz, CDCl3): δ 162.13 (d, J
= 248.6 Hz), 133.47 (d, J = 8.3 Hz), 119.59 (d, J = 3.6 Hz), 115.49
115.27, 86.15, 85.45, 64.11, 41.63, 40.03, 31.11, 30.24, 26.63, 26.05
ppm; 19F NMR (376 MHz, CDCl3): δ -112.0 ppm; HRMS-ESI (m/z) calcd
for C17H22NF [M+H]+: 260.1809, found 260.1807; IR (diamond tip): ν
2944, 2919, 2848, 2826, 1597, 1503, 1468, 1451, 1319, 1259, 1217,
1196, 1172, 1156, 1120, 1093, 1046, 1016, 983, 846, 829, 814, 606,
582, 529, 471, 433 cm-1.
4-(4-methoxyphenyl)-1-(4-methylbenzyl)-1H-1,2,3-triazole, P6, white
solid, yield 94%; 1H NMR (400 MHz, CDCl3) δ 7.74–7.67 (m, 2H), 7.53
(s, 1H), 7.19 (d, J = 1.8 Hz, 4H), 6.96–6.87 (m, 2H), 5.50 (s, 2H), 3.81
(s, 3H), 2.34 (s, 3H). 13C{1H} NMR (101 MHz, CDCl3): δ 159.5, 148.0,
138.7, 131.7, 129.8, 128.1, 127.0, 123.3, 118.5, 114.1, 55.3, 54.0, 21.2
ppm. Spectroscopic data for the compound P6 were consistent with the
previously reported ones.[30]
1-cyclohexyl-3-(4-methoxyphenyl)-N,N-dimethylprop-2-yn-1-amine, P11,
light-yellow oil, yield 88%; 1H NMR (400 MHz, CDCl3): δ 7.40–7.32 (m,
2H), 6.85–6.77 (m, 2H), 3.79 (s, 3H), 3.12 (d, J = 9.9 Hz, 1H), 2.27 (s,
6H), 2.15–2.05 (m, 1H), 2.03–1.95 (m, 1H), 1.79–1.71 (m, 2H), 1.70–
1.63 (m, 1H), 1.55–1.45 (m, 1H), 1.30–1.14 (m, 3H), 1.07–0.88 (m, 2H)
ppm; 13C{1H} NMR (101 MHz, CDCl3): δ 159.1, 133.0, 115.7, 113.8,
86.2, 84.8, 64.2, 55.3, 41.6, 40.1, 31.1, 30.3, 26.7, 26.1 ppm; HRMS-
ESI (m/z) calcd for C18H25NO [M+H]+: 272.2009, found 272.2006; IR
(diamond tip): ν 3038, 2930, 2851, 2822, 2779, 2667, 2536, 2214,
20151, 1884, 1703, 1657, 1606, 1570, 1509, 1467, 1450, 1414, 1339,
1317, 1289, 1247, 1226, 1173, 1122, 1104, 1086, 1035, 984, 942, 891,
850, 830, 803, 698, 644, 606, 584, 535, 488, 440 cm-1.
4-(4-fluorophenyl)-5-((4-fluorophenyl)ethynyl)-1-(2-iodobenzyl)-1H-
1,2,3-triazole, P7, white solid, yield 78%; 1H NMR (400 MHz, CDCl3): δ
8.22–8.1 (m, 2H), 7.89 (dd, J = 7.9, 1.3 Hz, 1H), 7.48–7.39 (m, 2H),
7.29 (td, J = 7.6 Hz, 1.3 Hz, 1H), 7.19–7.12 (m, 2H), 7.10–6.97 (m, 3H),
6.88 (dd, J = 7.8 Hz, 1.6 Hz, 1H), 5.74 (s, 2H) ppm; 13C{1H} NMR (101
MHz, CDCl3): δ 164.6, 164.2, 162.0, 139.6, 137.2, 133.8, 130.0, 128.9,
128.2, 128.1, 128.0, 126.3, 117.4, 115.9 (d, J = 10.8 Hz), 115.7, 101.8,
97.5, 74.7, 57.3 ppm; 19F NMR (376 MHz, CDCl3): δ -107.8, -112.2 ppm;
IR (diamond tip): ν 2226, 1604, 1563, 1514, 1494, 1461, 1432, 1359,
1230, 1218, 1154, 1039, 1012, 1001, 841, 829, 808, 752, 739, 700, 680,
650, 610, 585, 573, 549, 526, 437, 427, 404 cm-1.
3-(4-(tert-butyl)phenyl)-1-cyclohexyl-N,N-dimethylprop-2-yn-1-amine,
P12, yellow oil, yield 92%; 1H NMR (400 MHz, CDCl3): δ 7.41–7.35 (m,
2H), 7.33–7.29 (m, 2H), 3.13 (d, J = 9.9 Hz, 3H), 2.27 (s, 6H), 2.15–
2.05 (m, 2H), 2.03–1.95 (m, 2H), 1.28 (s, 9H), 1.23–1.12 (m, 2H), 1.05–
0.92 (m, 2H) ppm; 13C{1H} NMR (101 MHz, CDCl3): δ 150.9, 133.5,
131.4, 125.2, 115.5, 86.5, 85.7, 64.2, 41.6, 40.1, 34.7, 31.1, 30.3, 26.7,
26.7, 26.1 ppm; HRMS-ESI (m/z) calcd for C21H31N [M+H]+: 298.2529,
found 298.2539; IR (diamond tip): ν 2922, 2851, 2822, 2779, 1505,
1448, 1405, 1363, 1338, 1316, 1262, 1224, 1194, 1171, 1155, 1108,
1087, 1044, 1020, 984, 890, 850, 832, 736, 654, 605, 560, 527, 472
cm-1.
4-phenyl-5-(phenylethynyl)-1-(4-(trifluoromethyl)benzyl)-1H-1,2,3-
1
triazole, P8, white solid, yield 90%; H NMR (400 MHz, CDCl3) δ 8.20–
8.13 (m, 2H), 7.66–7.59 (m, 2H), 7.52–7.33 (m, 10H), 5.73 (s, 2H) ppm;
13C{1H} NMR (101 MHz, CDCl3): δ 148.3, 138.5, 131.5, 129.9 (d, J =
10.9 Hz), 128.8, 128.7, 128.6, 128.3, 126.2, 125.9 (d, J = 3.8 Hz),
121.1, 102.7, 52.3 ppm. 19F NMR (376 MHz, CDCl3): δ -62.8 ppm; IR
(diamond tip): ν 2944, 2919, 2848, 2826, 1504, 1468, 1450, 1217, 1156,
1093, 1046, 1016, 983, 846, 830, 814, 606, 582, 529, 471 cm-1.
Typical procedure for the A3 coupling reaction: In a vial fitted with a
screw cap, aldehyde (1.3 mmol, 1.0 eq), alkyne (1.4 mmol, 1.1 eq) and
amine (1.3 mmol, 1.1 eq) were dissolved in methanol (1 mL). Next, the
appropriate copper catalyst (0.5 mol%) was introduced to the reaction
mixture. The reaction was performed at room temperature and was
monitored by TLC (n-hexane/ethyl acetate, v/v = 7:3). After completion
of the reaction (20 minutes), the reaction mixture was extracted with
diethyl ether (3 x 1 mL). The combined organic phases were dried over
anhydrous MgSO4 and concentrated on a rotary evaporator. The crude
product was purified by column chromatography (n-hexane/ethyl
acetate, v/v = 8:2). The isolated product was dried under vacuum.
N-allyl-N-(1-cyclohexyl-3-mesitylprop-2-yn-1-yl)prop-2-en-1-amine, P13,
1
yellow oil, yield 84%; H NMR (400 MHz, CDCl3): δ 6.86 (d, J = 0.5 Hz,
2H), 5.82 (dddd, J = 17.2, 10.1, 8.3, 4.1 Hz, 2H), 5.21 (dtd, J = 17.2,
2.1, 1.0 Hz, 2H), 5.12–5.06 (m, 2H), 3.44 (d, J = 10.2 Hz, 1H), 3.34 (dt,
J = 4.0, 1.9 Hz, 1H), 3.30 (dt, J = 4.0, 1.9 Hz, 1H), 2.94 (dd, J = 14.3,
8.3 Hz, 2H), 2.40 (s, 6H), 2.26 (s, 3H), 2.16–2.08 (m, 2H), 1.78–1.70 (m,
2H), 1.68–1.57 (m, 2H), 1.29–1.17 (m, 3H), 1.09–0.97 (m, 1H), 0.95–
0.83 (m, 1H) ppm; 13C{1H} NMR (101 MHz, CDCl3): δ 139.9, 137.0,
127.5, 120.5, 116.7, 95.3, 83.0, 59.0, 54.1, 40.4, 31.4, 30.4, 26.7, 26.2,
26.0, 21.4, 21.2 ppm; HRMS-ESI (m/z) calcd for C24H33N [M+H]+:
336.2686, found 336.2693; IR (diamond tip): ν 2920, 2850, 2813, 1641,
1610, 1478, 1446, 1416, 1375, 1351, 1319, 1262, 1240, 1216, 1186,
1-cyclohexyl-N,N-dimethyl-3-fenylprop-2-yn-1-amine, P9, light-yellow oil,
yield 91%; 1H NMR (400 MHz, CDCl3): δ 7.47–7.40 (m, 2H), 7.33–7.26
(m, 3H), 3.15 (d, J = 10 Hz, 1H), 2.28 (s, 6H), 2.15–2.07 (m, 1H), 2.04–
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700523
European Journal of Organic Chemistry
FULL PAPER
1156, 1106, 1032, 993, 973, 916, 889, 850, 728, 711, 594, 573, 471
cm-1.
4,4,5,5-tetramethyl-2-(4-(trifluoromethyl)benzyl)-1,3,2-dioxaborolane,
1
P19, colourless oil, yield 96%; H NMR (400 MHz, CDCl3): δ 7.52–7.47
N-allyl-N-(3-(4-(tert-butyl)phenyl)-1-cyclohexylprop-2-yn-1-yl)prop-2-en-
1-amine, P14, yellow oil, yield 89%; 1H NMR (400 MHz, CDCl3) δ 7.39–
7.34 (m, 2H), 7.33–7.29 (m, 2H), 5.82 (dddd, J = 17.2, 10.2, 8.2, 4.2
Hz, 2H), 5.21 (dtd, J = 17.2, 2.0, 1.0 Hz, 2H), 5.09 (ddd, J = 10.2, 1.9,
1.2 Hz, 2H), 3.35–3.26 (m, 3H), 2.92 (dd, J = 14.3, 8.2 Hz, 2H), 2.15–
2.03 (m, 2H), 1.79–1.66 (m, 3H), 1.60–1.50 (m, 2H), 1.30 (s, 9H), 1.22–
1.12 (m, 2H), 1.05–0.95 (m, 1H), 0.90–0.80 (m, 1H) ppm; 13C{1H} NMR
(101 MHz, CDCl3): δ 150.9, 137.0, 131.4, 125.2, 120.7, 120.7, 116.6,
86.8, 86.6, 58.8, 53.9, 40.2, 34.7, 31.3, 31.2, 30.4, 26.7, 26.2, 26.0 ppm;
HRMS-ESI (m/z) calcd for C25H35N [M+H]+: 350.2842, found 350.2856;
IR (diamond tip): ν 2922, 2850, 1502, 1446, 1363, 1318, 1265, 1107,
993, 917, 890, 833, 643, 599, 560, 521 cm-1.
(m, 2H), 7.34–7.27 (m, 2H), 2.82–2.75 (m, 2H), 1.20 (bs, 12H) ppm;
13C{1H} NMR (101 MHz, CDCl3): δ 148.5, 128.3, 125.7, 125.1 (q, J =
3.8 Hz), 83.2, 29.8, 25.0, 24.8, 24.7 ppm; 19F NMR (376 MHz, CDCl3) δ
-62.27 ppm. Spectroscopic data for the compound P19 were consistent
with the previously reported ones.[31]
Acknowledgements
Authors are generously grateful to the Foundation for Polish
Science for financial support (Homing Plus programme /2013/8-
13, "Novel approaches to transition metal complexes based on
ligands containing sulfur moiety and their direct application in C-
H bond transformations"). The project was co-financed by the
European Union by the European Regional Development Fund,
Operational Program Innovative Economy 2009-2013. Project
was carried out using the infrastructure of Biological and
Chemical Research Centre of University of Warsaw.
Typical procedure for the β-hydroboration of internal alkynes and
alkenes: In dry and argon flushed a 5 mL flask were added the
appropriate copper complex (0.05 mol%), alkyne or alkene (1.3 mmol,
1.0 eq), B2(pin)2 (1.5 mmol, 1.1 eq) and NaOH (1 mol%, 0.0013 mmol).
Then was added dry methanol (0.1 mL) and CPME (1 mL). The
reaction mixture was stirred at room temperature for 18 h under an inert
atmosphere of argon. The reaction was monitored by TLC (n-
hexane/ethyl acetate, v/v = 7:3). After completion of the reaction, the
solvent was removed in vacuo, and the product was purified by column
Keywords: Copper Catalysis • NHC Ligands • CuAAC reaction •
A3 coupling reaction • β-hydroboration reaction
chromatography (n-hexane/ethyl acetate, v/v
= 9:1). The isolated
product was dried under vacuum.
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(m, 4H), 7.19 (s, 1H), 2.38 (dd, J = 7.5, 0.9 Hz, 2H), 1.30 (s, 12H), 1.09
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137.9, 128.9, 128.0, 127.0, 83.4, 24.8, 22.7, 22.3, 14.7, 14.1 ppm.
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dioxaborolane, P16, colourless oil, yield 95%; 1H NMR (400 MHz,
CDCl3): δ 7.34–7.28 (m, 2H), 7.11 (ddd, J = 3.6, 1.1, 0.6 Hz, 1H), 7.00
(dd, J = 5.1, 3.6 Hz, 1H), 2.56–2.46 (m, 2H), 1.52–1.36 (m, 4H), 1.28
(bs, 12H), 0.93 (t, J = 7.1 Hz, 3H) ppm; 13C{1H} NMR (101 MHz,
CDCl3): δ 140.8, 133.9, 129.6, 126.7, 126.6, 83.4, 31.4, 30.0, 24.7, 23.1,
14.1 ppm. Spectroscopic data for the compound P16 were consistent
with the previously reported ones.[32]
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4,4,5,5-tetramethyl-2-(naphthalen-1-ylmethyl)-1,3,2-dioxaborolane, P17,
colourless oil, yield 97%; 1H NMR (400 MHz, CDCl3): δ 8.08 (dd, J =
8.3, 1.1 Hz, 1H), 7.85–7.81 (m, 1H), 7.70–7.65 (m, 1H), 7.47 (ddd, J =
9.2, 7.8, 1.4 Hz, 2H), 7.41–7.34 (m, 2H), 3.23–3.17 (m, 2H), 1.24 (s,
12H) ppm; 13C{1H} NMR (101 MHz, CDCl3): δ 140.4, 133.8, 131.7,
128.6, 126.3, 125.5, 125.3, 125.0, 123.9, 83.1, 26.9, 25.0, 24.8 ppm.
Spectroscopic data for the compound P17 were consistent with the
previously reported ones. [33]
4,4,5,5-tetramethyl-2-(4-methylbenzyl)-1,3,2-dioxaborolane,
P18,
colourless oil, yield 94%; 1H NMR (400 MHz, CDCl3): δ 7.07 (dt, J =
8.5, 4.4 Hz, 4H), 2.72–2.65 (m, 2H), 2.29 (d, J = 3.4 Hz, 3H), 1.26 (bs,
12H) ppm; 13C{1H} NMR (101 MHz, CDCl3): δ 141.4, 134.8, 128.9,
128.8, 127.8, 125.4, 83.1, 29.8, 25.0, 24.8, 24.5, 21.0 ppm.
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Entry for the Table of Contents (Please choose one layout)
Layout 1:
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A facile and efficient synthesis of
novel family of NHC copper(I)
complexes is described. Presented
initiators promote actively various
transformations at room temperature
in high yields.
Copper Catalysis*
Anna Szadkowska*, Ewelina Zaorska,
Sebastian Staszko, Robert Pawłowski,
Damian Trzybiński and Krzysztof
Woźniak
Page No. – Page No.
Synthesis, structural characterization
and catalytic activities of sulfur-
functionalized NHC copper(I)
complexes
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