Selenium-catalyzed oxidative carbonylation of aniline and alcohols to n-phenylcarbamates

Article abstract of DOI:10.1080/00397910903134626

A facile one-pot, phosgene-free synthesis of N-phenylcarbamates is demonstrated. Catalyzed by selenium, oxidative carbonylation of aniline with alcohols in the presence of carbon monoxide and oxygen affords the corresponding N-phenylcarbamates, mostly in fair to good yields. Selenium can be easily recovered because of its phase-transfer catalysis function. Copyright

Full text of DOI:10.1080/00397910903134626

This article was downloaded by: [Universidad Autonoma de Barcelona]
On: 04 November 2014, At: 13:41
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered
office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Synthetic Communications: An
International Journal for Rapid
Communication of Synthetic Organic
Chemistry
Publication details, including instructions for authors and
subscription information:
http://www.tandfonline.com/loi/lsyc20
Selenium-Catalyzed Oxidative
Carbonylation of Aniline and Alcohols to
N-Phenylcarbamates
Xiaopeng Zhang a , Huanzhi Jing a & Guisheng Zhang a
a College of Chemistry and Environmental Science, Henan Normal
University , Xinxiang, Henan, China
Published online: 06 May 2010.
To cite this article: Xiaopeng Zhang , Huanzhi Jing & Guisheng Zhang (2010) Selenium-Catalyzed
Oxidative Carbonylation of Aniline and Alcohols to N-Phenylcarbamates, Synthetic Communications:
An International Journal for Rapid Communication of Synthetic Organic Chemistry, 40:11, 1614-1624,
DOI: 10.1080/00397910903134626
To link to this article: http://dx.doi.org/10.1080/00397910903134626
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the
“Content”) contained in the publications on our platform. However, Taylor & Francis,
our agents, and our licensors make no representations or warranties whatsoever as to
the accuracy, completeness, or suitability for any purpose of the Content. Any opinions
and views expressed in this publication are the opinions and views of the authors,
and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content
should not be relied upon and should be independently verified with primary sources
of information. Taylor and Francis shall not be liable for any losses, actions, claims,
proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or
howsoever caused arising directly or indirectly in connection with, in relation to or arising
out of the use of the Content.
This article may be used for research, teaching, and private study purposes. Any
substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &

Conditions of access and use can be found at http://www.tandfonline.com/page/terms-
and-conditions

Synthetic Communications1, 40: 1614–1624, 2010
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910903134626
SELENIUM-CATALYZED OXIDATIVE CARBONYLATION
OF ANILINE AND ALCOHOLS TO
N-PHENYLCARBAMATES
Xiaopeng Zhang, Huanzhi Jing, and Guisheng Zhang
College of Chemistry and Environmental Science, Henan Normal University,
Xinxiang, Henan, China
A
facile one-pot, phosgene-free synthesis of N-phenylcarbamates is demonstrated.
Catalyzed by selenium, oxidative carbonylation of aniline with alcohols in the presence of
carbon monoxide and oxygen affords the corresponding N-phenylcarbamates, mostly in fair
to good yields. Selenium can be easily recovered because of its phase-transfer catalysis
function.
Keywords: Aniline; N-phenylcarbamates; oxidative carbonylation; selenium
INTRODUCTION
The oxidative carbonylation of amines is currently a field of great interest,
because important carbamates can be obtained via oxidative carbonylation of
amines with alcohols.[1] Carbamates are useful compounds that are widely used to
make herbicides, pesticides, and fungicides in agrochemical industries[2] and to make
artificial leather, adhesive agents, elastic, fabric, and synthetic rubber in the polymer
industry.[3] Conventionally, carbamates can be obtained from the reaction of amines
with phosgene[4] or its derivatives.[5] However, this method suffers from drawbacks
such as multistep synthesis, the extreme toxicity of phosgene, and the generation
of corrosive HCl. Therefore, in recent years, many phosgene-free procedures have
been devised for new ecofriendly synthesis of carbamates.[6–10] Among them, the
one-pot procedure of catalytically oxidative carbonylation of amines with alcohols
is of particular importance from both synthetic and environmental standpoints.
Group VIII transition metals or their compounds are commonly used as catalysts
for this purpose.[11–14] However, the high cost and low availability of the
transition-metal catalyst system together with the complex and energy-consuming
separation process made this approach very uneconomical. During the past decades,
cheap and readily available selenium has been found to be an efficient and economi-
cal catalyst for the carbonylation of nitro aromatics,[15] amines,[16] and alcohols.[17]
Although selenium-catalyzed oxidative carbonylation of aliphatic amines with
Received April 2, 2009.
Address correspondence to Xiaopeng Zhang, College of Chemistry and Environmental Science,
Henan Normal University, Xinxiang 453007, Henan, China. E-mail: zhangxiaopengv@sina.com
1614

CARBONYLATION TO N-PHENYLCARBAMATES
1615
Scheme 1. Selenium-catalyzed oxidative carbonylation of aniline with alcohols to N-phenylcarbamates.
alcohols to the corresponding carbamates has been achieved,[18] no satisfactory
examples have been found in literature for the synthesis of N-phenylcarbamates from
the selenium-catalyzed oxidative carbonylation of aniline with alcohols. Thus,
further pursuit of diversely functionalized carbamates from this approach is still
significant.
We now report here a facile one-pot, phosgene-free synthesis of N-
phenylcarbamates from selenium-catalyzed oxidative carbonylation of aniline
with alcohols in the presence of carbon monoxide and oxygen (Scheme 1). The
main factors influencing the carbonylation reaction, such as temperature, time,
pressure, and the contents of catalyst, triethylamine, and alcohol, were investi-
gated. It was demonstrated that with triethylamine as cocatalyst, the selenium-
catalyzed oxidative carbonylation of aniline proceeded efficiently under opti-
mized reaction conditions with a series of alcohols to afford the corresponding
N-phenylcarbamates in fair to good yields.
RESULTS AND DISCUSSION
Effect of Temperature
To investigate the effect of the temperature on the synthesis of N-phenylcarbamates,
the selenium-catalyzed oxidative carbonylation reaction was conducted at different
temperatures, and the results are summarized in Table 1.
Accompanying the carbonylation of aniline with alcohol to the corresponding
N-phenylcarbamate was the competitive carbonylation reaction of aniline itself to
diphenylurea. Thus, aniline was completely consumed in 6 h at 120 ꢀC, affording
ethyl N-phenylcarbamate in 35% yield and a side product, diphenylurea, in 46%
yield, respectively (entry 1). With the increase of reaction temperature, the yield of
ethyl N-phenylcarbamate increased, whereas the yield of diphenylurea decreased
Table 1. Effect of temperature on selenium-catalyzed oxidative carbonylation of aniline with ethanol to
ethyl N-phenylcarbamatea
Entry Temperature (ꢀC) Conversion (%)b N-Phenylcarbamate yield (%)c Diphenylurea yield (%)c
1
2
3
4
5
120
140
160
180
200
100
100
100
100
100
35
72
78
85
85
46
21
15
8
7
aReaction conditions: aniline, 5 mmol; ethanol, 50 mmol; selenium, 0.25 mmol; triethylamine, 10 mmol;
CO, 1.6 MPa; O2, 0.4 MPa; time, 6 h.
bBased on aniline.
cIsolated yield.

1616
X. ZHANG, H. JING, AND G. ZHANG
Scheme 2. Alcoholysis of diphenylurea to N-phenylcarbamates.
(entries 2–4). This is most probably due to alcoholsis of diphenylurea in the
presence of excess ethanol under greater temperature (Scheme 2). The yield of ethyl
N-phenylcarbamate was greatest at 180 ꢀC (entry 4). With temperatures greater than
180 ꢀC, the yield of N-phenylcarbamate remained almost unchanged.
Effect of Time
The influence of reaction time on the carbonylation reaction is summarized in
Table 2. The results showed a fast rise both in the conversion of aniline and in the
product yield within the initial reaction period (entries 1 and 2). The reaction reached
a completion within 6 h with yield of 85% for ethyl N-phenylcarbamate (entry 3).
There was no distinct increase in the product yield with longer reaction period, most
probably because the reaction reached an equilibrium in 6 h.
Effect of Pco/Po2
Results in Table 3 show the influence of the content of carbon monoxide and
oxygen on the carbonylation reaction. The greater the oxygen content is, the less the
selectivity to ethyl N-phenylcarbamate becomes, and accordingly more of the side
product diphenylurea is generated. The product yield increased with the decrease
of oxygen content and reached the maximum when the pressure ratio of carbon
monoxide to oxygen was 4:1 (entries 1–3). Further decrease of oxygen content
resulted in the incomplete conversion of aniline (entry 4).
Effect of Alcohol Content
Excessive alcohol was necessary both to facilitate the carbonylation of aniline
with alcohol to the corresponding N-phenylcarbamate and to restrain the carbonyla-
tion of aniline itself to the side product, diphenylurea. Thus, the selectivity to the
Table 2. Effect of time on selenium-catalyzed oxidative carbonylation of aniline to ethyl
N-phenylcarbamatea
Entry Time (h) Conversion (%)b N-Phenylcarbamate yield (%)c Diphenylurea yield (%)c
1
2
3
4
2
4
6
8
76
90
67
78
85
85
5
6
8
7
100
100
aReaction conditions: aniline, 5 mmol; ethanol, 50 mmol; selenium, 0.25 mmol; triethylamine,
10 mmol; CO, 1.6 MPa; O2, 0.4 MPa; temperature, 180 ꢀC.
bBased on aniline.
cIsolated yield.

CARBONYLATION TO N-PHENYLCARBAMATES
1617
Table 3. Effect of Pco=Po2 on selenium-catalyzed oxidative carbonylation of aniline to ethyl
N-phenylcarbamatea
Entry Pco(MPa)=Po2(MPa) Conversion (%)b N-Phenylcarbamate yield (%)c Diphenylurea yield (%)c
1
2
3
4
1.2=0.8
1.4=0.6
1.6=0.4
1.8=0.2
100
100
100
90
53
67
85
81
41
26
8
5
aReaction conditions: aniline, 5 mmol; ethanol, 50 mmol; selenium, 0.25 mmol; triethylamine, 10 mmol;
temperature, 180 ꢀC; time, 6 h.
bBased on aniline.
cIsolated yield.
major product, ethyl N-phenylcarbamate, increased with the increase of ethanol con-
tent (Table 4, entries 1–3). Too little alcohol content resulted in not only the incom-
plete conversion of aniline but also poor selectivity to the corresponding carbamate
(entry 1), and there was no distinct increase with the corresponding carbamate yield
at a molar ratio of alcohol to aniline greater than 15 (entry 4).
Effect of Triethylamine Content
The influence of triethylamine as cocatalyst on the carbonylation reaction is
shown in Table 5. The reaction failed to proceed in the absence of triethylamine
(entry 1), whereas the aniline conversion and the product yield increased observably
with addition of triethylamine (entries 2 and 3), which indicated that a properly basic
condition was indispensable for this selenium-catalyzed carbonylation reaction. We
believe the role of triethylamine here is to promote the formation of the active car-
bonyl selenide (SeCO), which is formed in situ by the reaction of selenium with CO.
When the molar ratio of triethylamine to aniline reached 2, complete conversion of
aniline and maximum product yield could be achieved. Further increase of triethy-
lamine content failed to gain any increase in product yield (entry 4).
Effect of Selenium Content
Table 6 shows the representative results of the effect of selenium content on the
carbonylation reaction. The reaction could not proceed in the absence of selenium
Table 4. Effect of alcohol content on selenium-catalyzed oxidative carbonylation of aniline to ethyl
N-phenylcarbamatea
Entry Alcohol (mmol) Conversion (%)b N-Phenylcarbamate yield (%)c Diphenylurea yield (%)c
1
2
3
4
5
25
50
75
84
100
100
100
33
71
85
86
49
23
8
7
aReaction conditions: aniline, 5 mmol; selenium, 0.25 mmol; triethylamine, 10 mmol; CO, 1.6 MPa; O2,
0.4 MPa; temperature, 180 ꢀC; time, 6 h.
bBased on aniline.
cIsolated yield.

1618
X. ZHANG, H. JING, AND G. ZHANG
Table 5. Effect of triethylamine content on selenium-catalyzed oxidative carbonylation of aniline to ethyl
N-phenylcarbamatea
Entry Triethylamine (mmol) Conversion (%)b N-Phenylcarbamate yield (%)c Diphenylurea yield (%)c
1
2
3
4
0
5
0
88
0
71
85
85
0
6
8
7
10
15
100
100
aReaction conditions: aniline, 5 mmol; ethanol, 50 mmol; selenium, 0.25 mmol; CO, 1.6 MPa; O2,
0.4 MPa; temperature, 180 ꢀC; time, 6 h.
bBased on aniline.
cIsolated yield.
(entry 1). With the increase of selenium content, the conversion of aniline and
the product yield increased accordingly (entries 2 and 3). Aniline was completely
consumed, and the corresponding N-phenylcarbamate was obtained in 85% yield
when selenium content reached 0.25 mmol (entry 4).
Synthesis of N-Phenylcarbamates
Selenium-catalyzed oxidative carbonylation of aniline was carried out in the
presence of various alcohols under optimized reaction conditions (Table 7). As
shown in Table 7, the selenium-catalyzed oxidative carbonylation of aniline can tol-
erate structurally diverse alcohols, affording the corresponding N-phenylcarbamates
mostly in fair to good yields. The reaction seemed highly sensitive to steric factors.
Thus, for alcohols with short straight chains, the reaction proceeded well to give the
corresponding products in good yields (entries 1, 2, 4, and 7), whereas for alcohols
with branch components, poor yields were obtained because of their greater steric
hindrance (entries 3, 5, 8, and 11). Similarly, for alcohols with longer chains, the
yields of the corresponding N-phenylcarbamates were decreased with the increase
of their chain length, most probably attributable to their increasing steric bulkiness
(entries 10, 12, and 13). The greater the steric hindrance of the alcohols is, the lower
their reactivity becomes, and accordingly, the less corresponding product yields are
produced (entries 5 and 8). Thus, it was understandable that no desired products
Table 6. Effect of selenium content on selenium-catalyzed oxidative carbonylation of aniline to ethyl
N-phenylcarbamatea
Entry Selenium (mmol) Conversion (%)b N-Phenylcarbamate yield (%)c Diphenylurea yield (%)c
1
2
3
4
0
0
46
0
41
81
85
0
2
5
8
0.10
0.20
0.25
90
100
aReaction conditions: aniline, 5 mmol; ethanol, 50 mmol; triethylamine, 10 mmol; CO, 1.6 MPa; O2,
0.4 MPa; temperature, 180 ꢀC; time, 6 h.
bBased on aniline.
cIsolated yield.

CARBONYLATION TO N-PHENYLCARBAMATES
1619
Table 7. Selenium-catalyzed oxidative carbonylation of aniline in alcohol media to
N-phenylcarbamatesa
Entry
R
Alcohol
Product
Product yield (%)b
1
2
Ethyl
Propyl
1a
1b
1c
1d
1e
1f
2a
2b
2c
2d
2e
2f
85
87
30
83
43
0
3
Isopropyl
Butyl
4
5
sec-Butyl
tert-Butyl
Pentyl
6
7
1g
1h
1i
2g
2h
2i
83
58
0
8
Isopentyl
tert-Pentyl
Hexyl
9
10
11
12
13
1j
2j
67
25
64
42
Cyclohexyl
Heptyl
Octyl
1k
1l
2k
2l
1m
2m
aReaction conditions: aniline, 5 mmol; alcohol, 50 mmol; selenium, 0.25 mmol;
triethylamine, 10 mmol; CO, 1.6 MPa; O2, 0.4 MPa; temperature, 180 ꢀC; time, 6 h.
bIsolated yield.
were obtained when the carbonylation reaction proceeded with the highly branched
2-methylpropan-2-ol (1f) or 2-methylbutan-2-ol (1i).
Phase-Transfer Catalysis Function of Selenium Catalyst
One remarkable advantage of the present catalytic system is that selenium acts
as a phase-transfer catalyst. Before the reaction, the selenium catalyst is in the solid
state in the selenium-catalyzed system; during the reaction process, solid selenium
reacts with carbon monoxide under basic conditions to form SeCO, which can dis-
solve in the reaction mixture to form a homogeneous catalytic system. Then SeCO
reacts with the nucleophiles present in the reaction system (amine and alcohol) to
afford hydrogen selenide, which then is oxidized to solid selenium simultaneously
by oxygen to participate in the next catalytic cycle. Thus, the reaction system can
change reciprocally between heterogeneous and homogeneous systems during the
course of the carbonylation reaction. Upon completion of the reaction, the solid
selenium reappears in the presence of oxygen and can be easily separated from the
reaction mixtures by simple filtration.
Possible Reaction Pathway to N-Phenylcarbamates
A plausible route to N-phenylcarbamates is presented in Scheme 3. First, the
reaction was initiated by the formation of carbonyl selenide,[19] which was generated
in situ from carbon monoxide and selenium in the presence of triethylamine. Next, I
underwent nucleophilic addition of aniline to form phenylcarbamoselenoic Se-acid
salt II.[20] Then, the nucleophilic attack of alcohol on II produced the desired
N-phenylcarbamate III,[20] accompanied by the formation of hydrogen selenide

1620
X. ZHANG, H. JING, AND G. ZHANG
Scheme 3. Proposed reaction pathway to N-phenylcarbamates.
IV. Hydrogen selenide was then oxidized to selenium by oxygen for the upcoming
catalytic cycle.
CONCLUSION
In summary, a facile one-pot, ecofriendly synthesis of N-phenylcarbamates has
been developed. With cheap and easily available selenium as catalyst and triethyla-
mine as cocatalyst, the carbonylation reaction of aniline proceeded well with a series
of alcohols in the presence of carbon monoxide under optimized conditions to afford
the corresponding N-phenylcarbamates, mostly in fair to good yields. The phase-
transfer catalysis function of selenium make it very easy to separate the selenium
catalyst from the reaction mixture.
EXPERIMENTAL
Materials and Instruments
Selenium powder (99.95%), oxygen (99.9%), and carbon monoxide (99.9%)
were used as purchased. Aniline, alcohols, and other chemicals were analytic-reagent
grade and used without further purification. Melting points were determined on a
1
Keyi XT4 apparatus (Beijing, China) and were uncorrected. H NMR spectra were
measured on a Bruker DPX 400 spectrometer in CDCl3 or dimethylsulfoxide
(DMSO) with Me4Si as internal standard.
General Procedure for the Preparation of N-Phenylcarbamate
All the selenium-catalyzed oxidative carbonylation reactions were conducted
in a 100-mL stainless steel autoclave equipped with a magnetic stirrer. Aniline

CARBONYLATION TO N-PHENYLCARBAMATES
1621
(5 mmol), selenium (0.25 mmol), triethylamine (10 mmol), and alcohol (50 mmol)
were added to the autoclave, respectively. The reactor was sealed and flushed three
times with a mixed gas of carbon monoxide and oxygen (4:1). Then the mixed gas
was introduced into the autoclave (2.0 MPa), and the reactor was immersed in an
oil bath preheated to the required temperature with stirring. Upon completion, the
reactor was cooled to room temperature, and the residual gas was released. The reac-
tion mixture was stirred for 30 min to precipitate selenium, which was then collected
by suction. The filtrate was concentrated, and the residual was purified either by col-
umn chromatography (silica gel, ethyl acetate–petroleum ether, 1:10–1:15) or by
recrystallization from light petroleum ether to give N-phenylcarbamates. The purity
1
and structure of the product was checked by H NMR spectra.
Data
Ethyl N-Phenylcarbamate (2a). Mp 49–50 ꢀC (lit.[21] 53 ꢀC); 1H NMR
(400 MHz, DMSO-d6): d 9.61 (brs, 1H), 7.46–6.96 (m, 5H), 4.12 (q, 2H, J ¼ 7.2 Hz),
1.24 (t, 3H, J ¼ 7.2 Hz).
Propyl N-Phenylcarbamate (2b). Mp 51–52 ꢀC (lit.[21] 57–59 ꢀC);1H NMR
(400 MHz, CDCl3): d 6.63 (brs, 1H), 7.40–7.05 (m, 5H), 4.14 (t, 2H, J ¼ 6.8 Hz),
1.74–1.68 (m, 2H), 0.99 (t, 3H, J ¼ 7.4 Hz).
Isopropyl N-Phenylcarbamate (2c). Mp 82 ꢀC (lit.[21] 90 ꢀC);1H NMR
(400 MHz, CDCl3): d 6.53 (brs, 1H), 7.39–7.04 (m, 5H), 5.06–4.99 (m, 1H), 1.31
(d, 6H, J ¼ 6.0 Hz).
Butyl N-Phenylcarbamate (2d). Mp 61 ꢀC (lit.[21] 65 ꢀC); 1H NMR
(400 MHz, CDCl3): d 6.76 (brs, 1H), 7.42–7.06 (m, 5H), 4.14 (t, 2H, J ¼ 6.8 Hz),
1.71–1.64 (m, 2H), 1.49–1.39 (m, 2H), 0.98 (t, 3H, J ¼ 7.4 Hz).
1
sec-Butyl N-Phenylcarbamate (2e). Mp 65 ꢀC (lit.[22] 66–67 ꢀC); H NMR
(400 MHz, CDCl3): d 6.60 (brs, 1H), 7.42–7.05 (m, 5H), 4.89–4.85 (m, 1H),
1.71–1.56 (m, 2H), 1.29 (d, 3H, J ¼ 6.0 Hz), 0.97 (t, 3H, J ¼ 7.6 Hz).
Pentyl N-Phenylcarbamate (2g). Mp 47 ꢀC (lit.[23] 48 ꢀC); 1H NMR
(400 MHz, CDCl3): d 6.62 (brs, 1H), 7.41–7.06 (m, 5H), 4.18 (t, 2H, J ¼ 6.8 Hz),
1.73–1.66 (m, 2H), 1.42–1.34 (m, 4H), 0.94 (t, 3H, J ¼ 5.6 Hz).
Isopentyl N-Phenylcarbamate (2h). Mp 51 ꢀC (lit.[24] 55 ꢀC); 1H NMR
(400 MHz, CDCl3): d 7.18 (brs, 1H), 7.45–7.06 (m, 5H), 4.24 (t, 2H, J ¼ 6.8 Hz),
1.62–1.56 (m, 2H), 1.78–1.72 (m, 1H), 0.99 (t, 6H, J ¼ 4.8 Hz).
Hexyl N-Phenylcarbamate (2j). Mp 42 ꢀC (lit.[21] 44–45 ꢀC); 1H NMR
(400 MHz, DMSO-d6): d 9.56 (brs, 1H), 7.47–6.95 (m, 5H), 4.06 (t, 2H, J ¼ 6.6 Hz),
1.64–1.57 (m, 2H), 1.39–1.27 (m, 6H), 0.88 (t, 3H, J ¼ 6.8 Hz).
1
Cyclohexyl N-Phenylcarbamate (2k). Mp 80–81 ꢀC (lit.[25] 82–82.5 ꢀC); H
NMR (400 MHz, DMSO-d6): d 9.55 (brs, 1H), 7.47–6.94 (m, 5H), 4.59–4.64 (m,
1H), 1.90–1.21 (m, 10H).

1622
X. ZHANG, H. JING, AND G. ZHANG
Heptyl N-Phenylcarbamate (2 l). Mp 57 ꢀC (lit.[26] 61 ꢀC); 1H NMR
(400 MHz, CDCl3): d 6.60 (brs, 1H), 7.40–7.05 (m, 5H), 4.17 (t, 2H, J ¼ 6.8 Hz),
1.70–1.60 (m, 2H), 1.41–1.31 (m, 8H), 0.90 (t, 3H, J ¼ 6.8 Hz).
Octyl N-Phenylcarbamate (2 m). Mp 72 ꢀC (lit.[27] 74 ꢀC); 1H NMR
(400 MHz, CDCl3): d 6.59 (brs, 1H), 7.40–7.05 (m, 5H), 4.17 (t, 2H, J ¼ 7.0 Hz),
1.71–1.64 (m, 2H), 1.39–1.29 (m, 10H), 0.89 (t, 3H, J ¼ 6.4 Hz).
ACKNOWLEDGMENTS
We sincerely acknowledge the financial supports from the Program for Innova-
tive Research Team in University of Henan Province, China (2008IRTSTHN002)
and the Education Department of Henan Province, China (2009B150013).
REFERENCES
1. Kim, H. S.; Kim, Y. J.; Lee, H.; S.; Lee, D. C.; Chiny, S. Oxidative carbonylation of
aromatic amines by selenium compounds. J. Catal. 1999, 184, 526–534.
2. (a) Gupte, S. P.; Shivarkar, A. B.; Chaudhari, R. V. Carbamate synthesis by solid-base-
catalyzed reaction of disubstituted ureas and carbonates. Chem. Commun. 2001, 2620–
2621; (b) Aresta, M.; Quaranta, E. Carbon dioxide: A substitute for phosgene. Chem.
Tech. 1997, 27, 32–40; (c) Vauthey, I.; Valot, F.; Gozzi, C.; Fache, F.; Lemane, M. An
environmentally benign access to carbamates and ureas. Tetrahedron Lett. 2000, 41,
6347–6350.
3. (a) Wu, T. T.; Huang, J.; Arrington, N.; Dill, G. M. Synthesis and herbicidal activity of
a-heterocyclic carbinol carbamates. J. Agric. Food Chem. 1987, 35, 817–823; (b)
Dell’Amico, D. B.; Calderazzo, F.; Labella, L.; Marchetti, F.; Pampaloni, G. Converting
carbon dioxide into carbamate derivatives. Chem. Rev. 2003, 103, 3857–3898.
4. (a) Norwick, J. S.; Powell, N. A.; Nguyen, T. M.; Noronha, G. An improved method for
the synthesis of enantiomerically pure amino acid ester isocyanates. J. Org. Chem. 1992,
57, 7364–7366; (b) Tafesh, A. M.; Weiguny, J. A review of the selective catalytic reduction
of aromatic nitro compounds into aromatic amines, isocyanates, carbamates, and ureas
using CO. Chem. Rev. 1996, 96, 2035–2052.
5. (a) Uchiumi, P. S.; Ataka, K.; Matsuzaki, T. Oxidative reactions by a palladium–alkyl
nitrite system. J. Organomet. Chem. 1999, 576, 279–289; (b) Majer, P.; Randad, R. S.
A safe and efficient method for preparation of N,N0-unsymmetrically disubstituted ureas
utilizing triphosgene. J. Org. Chem. 1994, 59, 1937–1938; (c) Slocombe, R. J.; Hardy, E.;
Saunders, J. H.; Jenkins, R. L. Phosgene derivatives: The preparation of isocyanates,
carbamyl chlorides, and cyanuric acid. J. Am. Chem. Soc. 1950, 72, 1888–1891.
6. (a) Skoog, S. J.; Campbell, J. P.; Gladfelter, W. L. Homogeneous catalytic carbonylation
of nitroaromatics, 9: Kinetics and mechanism of the first N-O bond cleavage and structure
of the g-2-ArNO intermediate. Organometallics 1994, 13, 4137–4139; (b) Macho, V.;
Harustiak, M. New catalytic system for oxidative carbonylation of aniline. J. Mol. Catal.
1994, 91, L155–L159; (c) Aresta, M.; Quaranta, E. Alkali-metal-assisted transfer of the
carbamate group from phosphocarbamates to alkyl halides: A new easy way to
alkali-metal carbamates and to carbamate esters. J. Chem. Soc. Dalton Trans. 1992,
1893–1899.
7. Fukuoka, S.; Chono, M.; Kohno, M. A novel catalytic synthesis of carbamates by the
oxidative alkoxycarbonylation of amines in the presence of platinum group metal and
alkali metal halide or onium halide. J. Org. Chem. 1984, 49, 1458–1460.

CARBONYLATION TO N-PHENYLCARBAMATES
1623
8. Ragaini, F.; Cenini, S. Mechanistic studies of palladium-catalysed carbonylation reactions
of nitro compounds to isocyanates, carbamates and ureas. J. Mol. Catal. A: Chem. 1996,
109, 1–25.
9. Curini, M.; Epifano, F.; Maltese, F.; Rosati, O. Carbamate synthesis from amines
and dimethyl carbonate under ytterbium triflate catalysis. Tetrahedron Lett. 2002, 43,
4895–4897.
10. Salvatore, R. N.; Shin, II, S.; Nagle, A. S.; Jumg, K. W. Efficient carbamate synthesis via
a three-component coupling of an amine, CO2, and alkyl halides in the presence of
Cs2CO3 and tetrabutylammonium iodide. J. Org. Chem. 2001, 66, 1035–1037.
11. (a) Alper, H.; Hartstock, F. W. An exceptionally mild, catalytic homogeneous method for
the conversion of amines into carbamate esters. J. Chem. Soc. Chem. Commun. 1985, 16,
1141–1144; (b) Pisanu, T.; Chuang, S. S. C. Carbamate synthesis on Pd=C catalysts:
Gasꢁsolid versus slurry processes. Ind. Eng. Chem. Res. 2004, 43, 1192–1199.
12. (a) Li, K. T.; Peng, Y. J. Oxidative carbonylation of aniline using manganese-based
catalysts. J. Catal. 1993, 143, 631–634; (b) Gupte, S. P.; Chaudhari, R. V. Oxidative
carbonylation of aniline over Pd=C catalyst: Effect of promoters, solvents, and reaction
conditions. J. Catal. 1988, 114, 246–258.
13. Gupte, S. P.; Chaudhari, R. V. Kinetic modeling of oxidative carbonylation of
aniline over palladium=carbon-sodium iodide catalyst. Ind. Eng. Chem. Res. 1992, 31,
2069–2074.
14. Giannoccaro, P.; Nobile, C. F.; Moro, G. Oxidative carbonylation of aniline catalyzed by
Pd(II)-2,20-bipyridyl complex intercalated in a-zirconium-phosphate. J. Mol. Catal. 1989,
53, 349–357.
15. Wang, X. F.; Lu, S. W.; Yu, Z. K. Selenium-catalyzed carbonylation of nitroarenes to
symmetrical 1,3-diarylureas under atmospheric pressure. Adv. Synth. Catal. 2004, 346,
929–932.
16. Sonoda, N.; Yasuhara, T.; Kondo, K.; Ikeda, T.; Tsutsumi, S. New synthesis of ureas:
Reaction of ammonia or aliphatic amines with carbon monoxide in the presence of
selenium. J. Am. Chem. Soc. 1971, 93, 6344.
17. Kondo, K.; Sonoda, N.; Sakurai, H. Selenium catalyzed synthesis of carbonates: The
reaction of alkoxide with carbon monoxide and oxygen in the presence of selenium. Bull.
Chem. Soc. Jpn. 1975, 48, 108–111.
18. Kondo, K.; Sonoda, N.; Tsutsumi, S. A new synthesis of carbamates: The reaction of
carbon monoxide with amine and alcohol in the co-presence of selenium and triethyl-
amine. Chem. Lett. 1972, 373–374.
19. Sonoda, N. Selenium assisted carbonylation with carbon monoxide. Pure Appl. Chem.
1993, 65, 699–706.
20. Sonoda, N.; Yamamoto, G.; Natsukawa, K.; Kondo, K.; Murai, S. A new synthesis of
heterocycles by the reaction of amino alcohols or amino thiols with carbon monoxide
in the presence of selenium. Tetrahedron Lett. 1975, 16, 1969–1972.
21. Yang, Y.; Lu, S. W. Selenium-catalyzed reductive carbonylation of PhNO2 in alcohol
media to phenyl carbamates. Chin. J. Catal. 1999, 20, 224–226.
22. George, D. K.; Moore, D. H.; Brian, W. P.; Garman, J. A. Carbamate herbicides, relative
herbicidal, and growth-modifying activity of several esters of N-phenylcarbamic acid.
J. Agric. Food Chem. 1954, 2, 356–363.
23. Whitmore, F. C.; Popkin, A. H.; Whitaker, J. S.; Mattil, K. F.; Zech, J. D. The action of
primary Grignard reagents on t-butylacetyl chloride. J. Am. Chem. Soc. 1938, 60,
2462–2464.
24. Schicktanz, S. T.; Etienne, A. D.; Steele, W. I. Analysis of fusel oil by azeotropic distil-
lation. Ind. Eng. Chem. Anal. Ed. 1939, 11, 420–422.

1624
X. ZHANG, H. JING, AND G. ZHANG
25. Herbert, E.; Ungnade, D. V. N. The effect of bases on the hydrogenation of alkylphenols
in the presence of Raney nickel. J. Am. Chem. Soc. 1944, 66, 1218–1220.
26. Dominguez, X.; Lopez, I.; Franc, R. Simple preparation of a very active Raney nickel
catalyst. J. Org. Chem. 1961, 26, 1625.
27. Dewey, B. T.; Witt, N. F. Identification of alcohols. Ind. Eng. Chem. Anal. Ed. 1940, 12,
459–460.