Selective Synthesis of Secondary Arylcarbamates via Efficient and Cost Effective Copper-Catalyzed Mono Arylation of Primary Carbamates with Aryl Halides and Arylboronic Acids

Article abstract of DOI:10.1007/s10562-017-2277-0

Abstract: An efficient, selective and cost-effective procedure has been developed for mono N-arylation of primary alkyl and benzyl carbamates with aryl iodides and bromides by incorporating CuI as an inexpensive and commercially available catalyst. Despite previous reports on C–N coupling reactions, this process does not need expensive ligands and takes advantage of readily available and inexpensive ethylenediamine (EDA) as the ligand. Reaction times were relatively short and related N-arylated carbamates were obtained in excellent yields. Interestingly, replacing CuI with Cu(OAc)₂ allowed us to use arylboronic acids as coupling partner for this reaction. All products are well characterized by ¹H- and ¹³C-NMR, MS, melting point, IR and CHNS techniques.

Full text of DOI:10.1007/s10562-017-2277-0

Catalysis Letters
https://doi.org/10.1007/s10562-017-2277-0
Selective Synthesis of Secondary Arylcarbamates via Efficient and Cost
Effective Copper-Catalyzed Mono Arylation of Primary Carbamates
with Aryl Halides and Arylboronic Acids
Ali Reza Sardarian1 · Iman DindarlooInaloo1 · Milad Zangiabadi1
Received: 30 September 2017 / Accepted: 8 December 2017
© Springer Science+Business Media, LLC, part of Springer Nature 2017
Abstract
An efficient, selective and cost-effective procedure has been developed for mono N-arylation of primary alkyl and benzyl
carbamates with aryl iodides and bromides by incorporating CuI as an inexpensive and commercially available catalyst.
Despite previous reports on C–N coupling reactions, this process does not need expensive ligands and takes advantage of
readily available and inexpensive ethylenediamine (EDA) as the ligand. Reaction times were relatively short and related
N-arylated carbamates were obtained in excellent yields. Interestingly, replacing CuI with Cu(OAc)2 allowed us to use
arylboronic acids as coupling partner for this reaction. All products are well characterized by 1H- and 13C-NMR, MS, melt-
ing point, IR and CHNS techniques.
Graphical Abstract
Keywords Primary carbamates · N-Arylation · Cross-coupling · Copper iodide · Alkyl arylcarbamates · Secondary
carbamates
Electronic supplementary material The online version of this
1 Introduction
article (https://doi.org/10.1007/s10562-017-2277-0) contains
supplementary material, which is available to authorized users.
N-Substituted carbamates are an attractive class of chemi-
* Ali Reza Sardarian
cal compounds due to their widespread applications [1–4].
sardarian@shirazu.ac.ir
The biological effects of these substances have been dis-
1
closed greatly in many pharmaceutical compounds like
anti-diabetic, anti-estrogenic, anticancer, anti-inflammatory,
Chemistry Department, College of Sciences, Shiraz
University, Shiraz 71946 84795, Iran
Vol.:(0123456789)
1 3

A. R. Sardarian et al.
(CDI) [19], diethyl carbonates (DEC) [20], and dimethyl car-
bonate (DMC) [21]. While these substitutes provided safer
reaction conditions, toxicity was still a major drawback.
Oxidative carbonylation of amines was reported by Chen
for the synthesis of N-substituted carbamates [22] whereby
CO is used instead of the previous phosgene derivatives.
This reaction has been demonstrated to be catalyzed by the
presence of Pd, Ru, Ni, Zn, and Mn [23–26].
Another intriguing method was reductive carbonylation
of nitro compounds which is takes place in the presence of
certain transition metals such as Pd, Ru and Rh, as catalyst
[27–30].
The reaction of amines, carbon dioxide and alcohols has
been shown to be a reliable method to obtain N-substituted
carbamates. These reactions are carried out in the presence
of homogeneous catalysts like Sn, Ni, Ru, Ir, Cs [31–33] and
heterogeneous catalysts such as CeO2, TiO2–Cr2O3/SiO2 and
Cu–Fe/ZrO2–SiO2 [34–36].
Fig. 1 Examples of biologically active N-substituted carbamates
RNH2 + COCl2 + R'OH
O
O
R'OH
R'OH
R
R
n
NH3
In 2004, Wang provided these compounds via the alcoho-
lysis of urea derivatives as carbonyl sources [37].
Many other interesting processes were also developed
using Hoffman [38], Curtius [39], Lossen [40], and Schmidt
[41] rearrangements.
N
H
NH2
t
n
e
n
e
a
P
b
m
m
O
f
g
o
n
H
a
r
r
a
e
r
Metal
O2
Metal
RNH2 + CO + R'OH
RNO2 + CO + R'OH
MNCO + ArX + R'OH
Sn cat.
RNH2 + CO2 + R'OH
O
R'
R
O
N
H
In recent years there has been an ongoing effort by many
research groups focused on finding novel and efficient meth-
ods for synthesis of N-substituted carbamates through C–N
coupling reactions in the presence of Pd or Cu catalysts
[42–47]. For example, tert-butyl carbamate was used sepa-
rately by Hornberger [42] and Qin [43] to prepare N-aryl
tert-butyl carbamate in the presence of aryl halides as cou-
pling partners and Pd catalysts. In another report, CuI was
used as the catalyst for Ullmann–Finkelstein–Ullmann reac-
tion of amides, sulfonamides, and carbamates [44]. However,
these procedures suffer from different unfavorable conditions
like using an excess amount of base, high temperature and
high reaction times.
Metal
r
e
t
n
L
a
s
o
r
e
u
r
s
i
a
s
c
m
a
n
e
r
e
g
H
n
u
g
t
e
n
C
e
m
a
a
e
r
t
e
r
Pd or Cu
catalysts
H
n
a
t
e
r
O
O
R'OH
OH
R'OH
R
N
H
R
N3
O
R'
ArX
O
NH2
(Present work)
Scheme 1 A general overview of different methodologies for the syn-
thesis of secondary carbamates
Using Pd and Cu catalyzed coupling of isocyanate salts
with aryl halides or arylboronic acids has been suggested for
synthesis of N-aryl carbamates [45–47]. In this protocol, iso-
cyanate is initially coupled with an aryl halide or arylboronic
acid and then alcohol attacks the carbon center of N-aryl
isocyanate to produce the desired carbamate. Recently a pro-
tocol was described by Chikkade et al. which takes advan-
tage of a C–H activation method using a Cu catalyst and
Di-tert-butyl peroxide (DTBP) to synthesize N-substituted
carbamates in good yields [48].
anti-osteoporosis, anti-malarial, antiviral, anti-obesity, anti-
tumor, anti-Alzheimer and anti-HIV drugs [5–10].
These compounds also play considerable roles as interme-
diates in the synthesis of some polymers [11] and as protect-
ing groups in organic synthesis [12]. Moreover, they perform
a key role in modern drug design and medicinal chemistry
(Fig. 1) [13, 14]. Therefore, synthesis of N-substituted car-
bamates has been a subject of interest in recent researches.
Many methods have been proposed for the preparation
of N-substituted carbamates, some of which are illustrated
in Scheme 1.
Despite all merits of the aforesaid procedures, they suf-
fer from major shortcomings including toxicity of reagents,
limited scope of substrates, long reaction times, unfavora-
ble reaction conditions, expensive ligands, expensive metals
and moderate yields. Thus there is still a large demand for
finding an efficient and reliable method for preparation of
N-substituted carbamates.
The oldest of these methods was the reaction of amines
with phosgene, which due to its highly toxic nature [15] was
replaced with 1,1,1-trichloromethylformate (diphosgene)
[16], bis-(1,1,1-trichloromethyl) carbonate (triphosgene)
[17], trichloroacetyl chloride [18], 1,1-carbonyl diimidazole
1 3

Selective Synthesis of Secondary Arylcarbamates via Efficient and Cost Effective…
In continuation of our ongoing research on the chemistry
of carbamates [49] to find a novel, efficient, and cost-effec-
tive protocol for N-arylation primary carbamates [50] and
efficiency of Cu catalysts in C–N bond formations [51–58],
herein, we introduce an efficient and cost effective proce-
dure for selective mono N-arylation primary carbamates to
address some of the limitations of previous methods reported
in the literature and to be applicable for N-arylation of a
wide range of alkyl and benzyl carbamates by aryl halides
and arylboronic acids in the presence of readily available and
inexpensive Cu salt and diamine ligand.
aryl halide (1 mmol) in 2 mL toluene and the mixture was
stirred for the appropriate time, which was determined by
TLC monitoring, at 100 °C. After completion of the reac-
tion, the catalyst was removed by filtration and 20 mL H2O
was added to the filtrate. The resultant mixture was extracted
with CHCl3. Then the organic phase was washed with water
(2×10 mL) and dried over anhydrous Na2SO4. After evapo-
ration of CHCl3 under reduced pressure, the corresponding
crude product was purified by flash chromatography to give
the desired pure cross-coupling product in good to excellent
yield. In the case of using arylboronic acids as coupling
partners, Cu(OAc)2 was employed instead of CuI.
2 Experimental
3 Results and Discussion
All chemicals were purchased from the Merck, Fluka and
Aldrich Chemical companies in high purity.
Regarding Cu catalyzed C–N coupling history for nitrogen
containing compounds and our initial effort on this reac-
tion for synthesis of alkyl or aryl arylcarbamates, it was
revealed that presence of a ligand is crucial for the reaction
to proceed. Thus we started to explored the effect of different
ligands (10 mol %) on the reaction of n-propyl carbamate
(1 mmol) with phenyl iodide (1 mmol) as the model reac-
tion in the presence of CuI (10 mol %), K2CO3 (1.5 mmol)
and toluene (2 mL) at 100 °C. Various classes of biden-
tate ligands with nitrogen and oxygen chelating atoms were
tested. As it is depicted in Fig. 2, ligands 1, 2 and 4 showed
the highest reactivity. Based on an economic point of view,
EDA, which is cheapest one, was selected as the best of
The products were characterized by their spectral and
physical data such as NMR, FT-IR, MS, CHNS and melting
point. 1H and 13C NMR spectra were recorded with Bruker
Avance DPX 250 MHz instruments with Me4Si or solvent
resonance as the internal standard. Fourier transform infra-
red (FTIR) spectra were obtained using a Shimadzu FT-IR
8300 spectrophotometer. Elemental analysis was done on a
2400 series PerkinElmer analyzer. The mass spectra were
recorded on a Shimadzu GC-MS QP 1000 EX instrument.
Melting points were determined on a Mel–Temp apparatus
and were uncorrected. Determination of the purity of the
substrate and monitoring of the reaction were accomplished
by thin-layer chromatography (TLC) on a silica–gel poly-
gram SILG/UV 254 plates.
2.1 General Procedure for the Synthesis of Primary
Carbamates
According to the reported procedure [49] a mixture of
alcohol (1 mol), potassium cyanate (1.5 mmol) and DBSA
(1.5 mmol) was pulverized in a mortar to provide a uni-
form powder. Then the mixture was maintained in an oven
at 60 °C for 1 h. After completion of the reaction, which was
determined by TLC monitoring, the resulting powder was
extracted by the addition of CH2Cl2 (15 mL) and saturated
aqueous solution of NaHCO3 (15 mL). Then the organic
layer was washed with water (3×15mL), dried over anhy-
drous Na2SO4 and concentrated to give the crude desired
product, which was purified by recrystallization from diethyl
ether.
NH2
NHMe
NMe2
NH2
NH2
NH2
NHMe
NMe2
N
N
1
2
3
4
5
t-Bu
OH
O
O
NH
OH
O
no
ligand
N
NMe2
t-Bu
OH
O
2.2 General Procedure for the Synthesis of Alkyl
Aryl Carbamates
6
8
9
10
7
CuI (10 mol%) and EDA (10 mol%) were added to a mixture
Fig. 2 The effect of various ligands on the C–N coupling bond forma-
tion of n-propyl carbamate and phenyl iodide
of O-alkyl carbamate (1 mmol), NaOtBu (1.5 mmol) and
1 3

A. R. Sardarian et al.
choice ligand for the rest of study. This is a great achieve-
ment regarding the previous reports on the C–N coupling
reactions in which expensive ligands had been consumed
[59–62].
effective base (Table 2, entry 5), although the other inorganic
bases like K2CO3, CsCO3 and K3PO4 are also somehow effi-
cient (Table 2, entries 1–4).The effect of several common
solvents was also examined and the model showed to be the
most efficient in toluene (Table 2, entry 5) and, except in
dioxane that the yield of reaction was 88% (Table 2, entry 6),
the model reaction did not proceed at all in the other solvents
(Table 2, entries 7–9). Optimizing of temperature showed
that the reaction has its highest efficiency at 100 °C and the
yield of the model reaction decreases at lower temperatures
(Table 2, entry 10) and running the reaction at higher tem-
perature is not led to any improvement in efficiency of the
reaction (Table 2, entry 11).
In the next step, the catalytic activity of various Cu
sources, such as Cu powder, Cu(I) and Cu(II) salts, was stud-
ied on the model reaction in the presence of EDA (10 mol%).
According to the obtained results (Table 1), although almost
all Cu salts carry out the reaction with moderate to good
yields, CuI is the best one (Table 1, entry 3) with shortest
reaction time.
After optimization of the copper source, the effect of dif-
ferent bases was examined in toluene as the solvent, which
the related results are presented in Table 2. According to
these results, sodium tert-butoxide show to be the most
Finally, the effect of different amounts of CuI and
EDA was explored on the reaction of n-propyl carbamate
(1 mmol) and phenyl iodide (1 mmol) in toluene and in the
presence of NaOtBu. According to the data summarized in
Table 2, the best result is obtained when 10 mol% of EDA
and CuI are employed (Table 2, entry 5). The results of opti-
mization study revealed that the best reaction conditions are:
alkyl carbamate (1 mmol), aryl halide (1 mmol), NaOtBu
(1.5 mmol), CuI (10 mol%), EDA (10 mol%), toluene (2 mL)
at 100 °C.
Table 1 The catalytic activity of copper catalysts on the preparation
of n-propyl phenylcarbamate
Entry
Copper source
Time (h)
Yield (%)
1
2
3
4
5
6
7
8
9
Cu powder
CuCl
CuI
CuCl2
CuBr2
12
5
5
6
6
12
12
6
Trace
75
85
57
62
36
45
70
66
With the optimized conditions in hand, generality, ver-
satility, and scope of reaction were explored. For this pur-
pose, a wide range of primary alkyl carbamates was chosen
as starting material and their C–N coupling reaction with
aryl iodide was investigated, which their results are repre-
sented in Table 3. According to the information obtained,
primary alkyl carbamates carry out the reaction very well
and produce the corresponding alkyl arylcarbamates in
excellent yields and interestingly in short reaction times
CuO
Cu(acac)2
Cu(OAc)2
CuSO4
6
Reaction conditions: n-propyl carbamate (1 mmol), phenyl iodide
(1 mmol), EDA (10 mol%), copper catalyst (10 mol%), K2CO3
(1.5 mmol), toluene (2 mL) at 100 °C
Table 2 Optimization of the
Entry
CuI (Mol%)
EDA (Mol%)
Solvent
Base
Temp (°C)
Yield (%)
reaction parameters of n-propyl
carbamate with phenyl iodide
after 5 h
1
2
3
4
5
6
7
8
10
10
10
10
10
10
10
10
10
10
10
10
10
10
5
10
10
10
10
10
10
10
10
10
10
10
5
15
20
10
10
10
Toluene
Toluene
Toluene
Toluene
Toluene
Dioxane
DMSO
EtOH
K2CO3
CsCO3
K3PO4
Et3N
100
100
100
100
100
100
120
Reflux
Reflux
50
120
100
100
100
100
100
100
85
87
66
31
92
88
Trace
0
NaOtBu
NaOtBu
NaOtBu
NaOtBu
NaOtBu
NaOtBu
NaOtBu
NaOtBu
NaOtBu
NaOtBu
NaOtBu
NaOtBu
NaOtBu
9
DMF
0
10
11
12
13
14
15
16
17
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
27
91
61
92
90
68
90
92
8
15
1 3

Selective Synthesis of Secondary Arylcarbamates via Efficient and Cost Effective…
Table 3 Mono N-arylation
O
of various primary alkyl
I
R
O
carbamates with phenyl iodide
NH
O
CuI (10 mol%), EDA
R
NH2
O
100 °C
NaOtBu, toluene,
X
R= Alkyl, benzyl
X
Entry
1
R
Product
O
Time/h Yield/%
NH
O
Ethyl
4
4
4
93
92
90
O
NH
O
2
3
n-Propyl
n-Butyl
O
NH
O
O
NH
O
4
5
i-Propyl
4.5
4.5
89
87
O
NH
NH
O
2-Butyl
O
O
6
i-Butyl
4
91
1 3

A. R. Sardarian et al.
Table 3 (continued)
O
NH
O
7
8
t-Butyl
5
5
85
O
NH
NH
O
Cyclohexyl
88
82
O
O
9
Menthyl
5
O
NH
NH
O
10
11
Benzyl
Benzyl
5
88
85
O
O
5.5
O
NH
O
12
Benzyl
6
43
compared to the majority of methods reported in the litera-
ture [42–46]. The protocol is also effective for N-arylation
of tert-butyl carbamate, which is widely used as protect-
ing group in organic synthesis (Table 3, entry 7). Benzyl
carbamates, which are important compounds in organic
synthesis, undergo the C–N coupling reaction as well as
the other primary carbamates and give the desired products
in good to excellent yields (Table 3, entries 10–17). The
1 3

Selective Synthesis of Secondary Arylcarbamates via Efficient and Cost Effective…
Table 3 (continued)
O
NH
O
13
14
Benzyl
Benzyl
6
5
80
91
O
NH
O
NO2
NH
O
O
15
Benzyl
5
90
O
O
NH
O
O
16
17
Benzyl
Beznyl
5
90
83
Br
O
NH
5.5
S
Reaction conditions: alkyl carbamate (1 mmol), aryl iodide (1 mmol), NaOtBu (1.5 mmol), CuI (10
mol%), EDA (10 mol%) in 2 mL toluene at 100 °C
presence of substitution in the ortho position, such as methyl
In addition, the coupling reaction of n-propyl carba-
mate with aryl halides was examined, which its results
are exhibited in Table 4. According to these data, various
aryl iodides with electron donating and electron withdraw-
ing substituents undergo the C–N coupling reaction effi-
ciently and give the corresponding secondary carbamates
in excellent yields. However, aryl iodides bearing electron
withdrawing groups give slightly higher yields. Moreover,
3-iodothiophene, as a heterocyclic aromatic iodide, reacts
group in 2-methyl iodobenzene, causes a drastic decrease
in the yield of reaction after 6 h (Table 3, entry 12), which
might be due to steric effect.
N-arylation of aryl carbamates was also carried out but
all efforts for isolation and purification of the desired prod-
ucts via chromatographic techniques were failed probably
because of their instability, which had been mentioned
before by Buchwald et al. [47].
1 3

A. R. Sardarian et al.
Table 4 Cu catalyzed mono
N-arylation of primary n-propyl
carbamates with various aryl
halides
O
O
CuI, EDA, NaOtBu
toluene, 100 °C
Ar
Ar
X
N
H
O
NH2
O
X=Cl,Br,I
Entry
1
Aryl-X
X
Product
X
Time/h
Yield/%
81
O
Br
5
12
4
NH
O
Cl
0
O
I
92
X
NH
O
2
3
Br
5
83
CN
X
CN
O
I
4
6
4
89
78
93
NH
O
Br
O
X
I
NH
O
O
4
5
NO2
X
Br
5
4
86
89
NO2
O
O
I
NH
Br
5
82
O
1 3

Selective Synthesis of Secondary Arylcarbamates via Efficient and Cost Effective…
Table 4 (continued)
O
O
O
I
4
4
92
86
X
NH
O
O
6
Br
Cl
Cl
X
NH
7
I
I
4
4
91
87
Br
Br
X
NH
O
O
8
S
S
O
O
I
4
5
87
80
X
NH
NH
9
Br
X
O
O
10
I
4
83
O
O
O
Reaction conditions: n-propyl carbamate (1 mmol), aryl halide (1 mmol), NaOtBu (1.5 mmol), CuI (10
mol%), EDA (10 mol%) in 2 mL toluene at 100 °C
with n-propyl carbamate and produces the desired product
on the reaction yield and reaction time. In contrast to aryl
iodides and bromides, aryl chlorides are inactive toward
C–N bond formation reaction.
in high yield (Table 4, entry 8).
Also the results registered in Table 4 disclose which aryl
bromides carry out the reaction as well as aryl iodides but
with slightly lower yields. Among aryl bromides, those
with electron withdrawing groups show a positive effect
Regarding to the difference in reactivity among aryl
iodides, bromides and chlorides, the selective C–N
coupling reaction of various dihalobenzenes, such as
1 3

A. R. Sardarian et al.
O
1-chloro-4-iodobenzene, 1-bromo-4-chlorobenzene, and
1-bromro-4-iodobenzene, with n-propyl carbamate was
studied in the presence of CuI. The results revealed that
C–I is more reactive than C–Br, and C–Br than C–Cl, and
N-arylation of the abovementioned dihalobenzenes produces
n-propyl 4-bromophenyl carbamate and n-propyl 4-chloro-
phenyl carbamate quantitatively (Table 4, entries 6 and 7).
To broaden the scope of protocol, mono arylation
of primary carbamates with arylboronic acids was also
explored. Therefore, phenylboronic acid (1 mmol) was
treated with n-propyl carbamate (1 mmol) in the presence
of CuI(10 mol%), EDA (10 mol%) and NaOtBu (1.5 mmol)
in toluene (2mL) at 100 °C. After 12 h, the isolated yield of
product, n-propyl phenylcarbamate, was only 28%. Surpris-
ingly, using Cu(OAc)2 instead of CuI, as the catalyst, pro-
vided a drastic improvement in the yield of reaction (82%)
after 6 h. 4-Methylphenylboronic acid and 4-nitrophenylbo-
ronic acid also underwent the C–N bond formation reaction
in high yields however in longer reaction times compared to
the related aryl iodides. (Scheme 2).
O
I
I
O
NH
CuI(10mol%), EDA(10mol%)
(1.5mmol), Toluene(2mL),
O
NH2
NH
NaOtBu
100oC
100oC
93%
1
2 mmol
mmol
O
CuI(10mol%), EDA(10mol%)
No Reaction
O
NaOtBu
(1.5mmol), Toluene(2mL),
1
mmol
1
mmol
Scheme 3 Study of selective mono N-arylation of n-propyl carba-
mates
Oxidative addition of ArX results in the Cu(III) complex III.
Then reductive elimination provides IV as the final product
and regenerates Cu(I) complex I (Fig. 3).
4 Conclusions
In conclusion, we have introduced an efficient, selective,
cost-effective and operationally simple method for the
mono N-arylation of various primary alkyl carbamates.
The other highlights of this protocol are: (a) using less
toxic and inexpensive catalyst (CuI), (b) using inexpensive
and available ligand (EDA), (c) broad scope regarding car-
bamate substrate, (d) producing high to excellent yield of
secondary carbamates in relatively short reaction time and
(e) tolerance of most of functional groups under reaction
conditions. This protocol opens a new opportunity for effi-
cient, selective and cost-effective synthesis of secondary
N-aryl carbamates via a C–N arylation reaction.
In the next step, two experiments were designed to con-
firm selectivity of the present method toward mono N-aryla-
tion of primary carbamates. In the first experiment, 1 mmol
n-propyl carbamate was treated with 2 mmol phenyl iodide
under the optimized reaction condition. It was observed that
in spite of using an excess amount of phenyl iodide, only
mono N-arylation took place and the product of diarylation
was not detected in the reaction mixture by TLC monitoring
(Scheme 3). In the second experiment, 1 mmol n-propyl phe-
nylcarbamate, as a secondary carbamate, was treated with
1 mmol phenyl iodide under the optimized reaction condi-
tions but in the contrast to the reported methods in the litera-
ture in which secondary carbamates had been successfully
converted to tertiary carbamates in the reaction with aryl
halides [63, 64], n-propyl phenylcarbamate did not undergo
N-arylation and remained intact (Scheme 3).
L
L
O
O
Cu(I)
R
R
Ar
NH2
O
N
H
O
X
I
According to the literature reports [45, 46, 65] and the
results obtained from this study, the following probable
mechanism can be suggested. In the first step, with sequen-
tial deprotonation and anion exchange, complex II is formed.
IV
NaOtBu
+
NaX
HOtBu
O
O
Ar
Cu(III)
X
L
R
L
Cu(I)
L
R
N
H
O
N
H
O
O
B(OH)2
L
III
II
O
Cu(OAc)2 (10 mol%)
EDA
O
NH
X
(10 mol%)
O
NH2
-
NaOtBu Toluene
-
X
100 °C 6h
Yield
82%
85%
76%
X: H
X: NO2
X: CH3
ArX
Fig. 3 The plausible mechanism of N-arylation reaction of primary
Scheme 2 The reaction of arylboronic acids as coupling partner in
alkyl carbamates in the presence of CuI
the formation of alkyl arylcarbamates
1 3

Selective Synthesis of Secondary Arylcarbamates via Efficient and Cost Effective…
34. Honda M, Sonehara S, Yasuda H, Nakagawa Y, Tomishige K
(2011) Green Chem 13:3406
Acknowledgements Authors gratefully acknowledge the financial sup-
port of this work by the research council of Shiraz University.
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