Stoichiometric Reactions of CO2 and Indium-Silylamides and Catalytic Synthesis of Ureas

Article abstract of DOI:10.1002/anie.201708921

The indium compounds In(N(SiMe₃)₂)₂Cl?THF (2) and In(N(SiMe₃)₂)Cl₂?(THF)_n (3) were shown to react with CO₂ to give [(Me₃Si)₂N)InX(μ-OSiMe₃)]₂ (X=N(SiMe₃)₂ 4, Cl 5). 0.05–2.0 mol % of the species 3 acts as a pre-catalyst for the conversion of aryl and alkyl silylamines under CO₂ (2–3 atm) to give the corresponding ureas in 70–99 % yields. A proposed mechanism is supported by experimental and computational data.

Full text of DOI:10.1002/anie.201708921

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Accepted Article
Title: Stoichiometric Reactions of CO2 and Indium-Silylamides and
Catalytic Synthesis of Ureas
Authors: Maotong Xu, Andrew Jupp, and Douglas Wade Stephan
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Angewandte Chemie International Edition
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COMMUNICATION
Stoichiometric Reactions of CO
2
and Indium-Silylamides and Catalytic
Synthesis of Ureas
Maotong Xu, Andrew R. Jupp and Douglas W. Stephan*
Dedication ((optional))
Abstract: The indium compounds In(N(SiMe
In(N(SiMe )Cl •(THF) (3) were shown to react with CO
(Me Si) N)InX(-OSiMe )] (X = N(SiMe 4, Cl 5). 0.05-2.0 mol% of
the species 3 acts as a pre-catalyst for the conversion of aryl and alkyl
silylamines under CO (2-3 atm.) to give the corresponding ureas in
0-99% yields. A proposed mechanism is supported by experimental
and computational data.
3
)
2
)
2
Cl•THF (2) and
temperature of 100 °C and at 200 psi CO
2
pressure.[11] Deng’s
group[
12]
showed that polymer-supported gold nanoparticles
)
3 2
2
n
2
to give
[
3
2
3
2
)
3 2
effectively catalyze the carbonylation of aliphatic cyclohexyl and
benzylamines to afford the corresponding ureas. De Vos et al.[
found that Cs-based catalysts and N-methylpyrrolidone permitted
the conversion of sterically unhindered aliphatic amines to urea in
13]
2
7
good yield. Similarly, CeO
2
and CsOH in ionic liquids catalyzed
the formation of aliphatic ureas,[
14]
although these reactions
(25–60 atm.) and high
required elevated pressures of CO
2
Urea and its derivatives are used in biological studies,
analytical chemistry, pharmaceutical applications, polymer
temperature (130–180 °C). It is also noteworthy that these
catalysts are inefficient or showed no reactivity towards aromatic
amines.
[1]
sciences, agrochemicals and organic synthesis. Traditionally,
urea derivatives are prepared via the stoichiometric reaction of
amines and isocyanates derived from either Hofmann
[
2]
rearrangement of amides or Curtius rearrangement of acyl
azides.[ Furthermore, urea derivatives are also accessible via
the reaction of amines with highly toxic phosgene and phosgene
analogs.[4] The Buchwald group reported a palladium-catalyzed
cross-coupling of aryl chlorides and triflates with sodium cyanate
to produce isocyanates in situ followed by a stoichiometric
reaction with amines to yield urea derivatives,[5] whereas catalytic
oxidative carbonylation of amines in the presence of carbon
monoxide has also provided alternative routes to ureas.[6]
3]
Alternative synthetic protocols that exploit CO
of the carbonyl fragment have also been targeted. As early as the
970s, Yamazaki and co-workers[7] showed that the
stoichiometric reaction of amines and CO in the presence of
2
as a source
1
2
diphenyl phosphite afforded N,N'-diphenyl or N,N'-dicyclohexyl
ureas. Subsequently, Ogura and co-workers[8] showed that
benzhydrylamine could be converted to urea in the presence of
stoichiometric carbodiimide and excess pyridine under high
pressures of CO
workers[9] have described the reaction of silylamines under
supercritical CO (140 atm.) at 120 °C which proceeds via the
2
(60 atm.). More recently, Holmes and co-
Scheme 1 Examples of urea synthesis.
2
initial formation of O-silylcarbamates and subsequent reaction
with silylamine to give the corresponding urea in yields ranging
from 13-85%.
Stoichiometric main group reactivity and catalysis is an area
that has garnered considerable attention in recent years. Among
the transformations of particular interest are those involving
Catalytic conversion of CO
2
to urea has also been
studied.[10] Laine, in a pioneering work, reported on the Ru
transformations of CO
we previously reported the use of frustrated Lewis pairs (FLPs) to
2
by main group catalysts.[15] For example,
3
(CO)12-
catalyzed synthesis of urea derivatives by reacting CO
2
with
sequester CO
2
.[16] While stoichiometric reduction to methanol or
PhNH(SiMe ), where the reactions were carried out at a
3
CO[
17]
has been observed for such FLP systems, catalytic
to CO was achieved using a Zn-based Lewis
reduction of CO
2
acid catalyst.[18] In addition, our group, as well as the groups of
Ashley,[19] Piers,[20] and Fontaine[21] have described the borane-
[*]
M. Xu, Dr. A. R. Jupp, Professor Dr. D. W. Stephan
Department of Chemistry, University of Toronto
80 St. George St, Toronto Ontario M5S 3H6 (Canada)
mediated catalytic hydrogenation or hydrosilylation of CO
we further the available main group-catalyzed transformations of
CO by developing indium-based catalysts for the conversion of
2
. Herein,
E-mail: dstephan@chem.utoronto.ca
Supporting information for this article is given via a link at the end of
the document. Crystallographic data were deposited: CCDC
2
both aliphatic and aromatic silylamines to the corresponding
ureas in good yield under comparatively mild conditions.
1571421-1571423.
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Angewandte Chemie International Edition
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COMMUNICATION
The
series
of
compounds
In(N(SiMe
)Cl •(THF)
3
)
2
)
3
(1),
screenings, the indium complexes 2, 3 and InCl
as catalysts in the reaction of 20 equivalents of C
with CO (3 atm.) in toluene-d . After 20 hours at reflux, 3 provided
3
were evaluated
[22]
In(N(SiMe
3
)
2
)
2
Cl•THF (2) and In(N(SiMe
3
)
2
2
n
(3) were
6
H
5
NH(SiMe )
3
prepared by minor modifications of the literature method involving
a salt metathesis reaction of Na(N(SiMe ) and InCl
.[4d-g, 23] In the
case of compounds 2 and 3 crystallographic studies confirmed
the formulations (Figure 1). Compound 2 exhibits a distorted
tetrahedral geometry about indium, with coordination to two
amide ligands, chloride and THF. The In-N bond distances are
2
8
3
)
2
3
50% (Table 1, Entry 1) yield of the urea (C
evidenced by H NMR spectroscopy, while 2 and InCl
6
H
5
NH)
2
CO 6, as
gave only
1
3
20 and 10%, respectively. In a similar fashion, 5 mol% 3 fully
converted 4-MeC NH(SiMe ) to the corresponding urea 7 in 24
hours (Table 1, Entry 2), while 4-BrC NH(SiMe ) showed no
6
H
4
3
6
H
4
3
2
.061(1) Å and 2.062(1) Å, while the In-Cl is 2.3976(4) Å. The THF
reaction after 48 hours (Table 1, Entry 3). These contrasting
results suggest that catalysis is observed for the strongly
nucleophilic amine, suggesting that cleavage of the
thermodynamically stable dimer 5 is required for catalysis. To
probe this end, equal amounts of 5 mol% of 3 and pyridine were
is disordered and precludes meaningful analysis of the In-O
distance. In contrast, compound 3 adopts a trigonal bipyramidal
geometry, with coordination of two axial THF molecules. The In-
Cl bond lengths are 2.3714(7) Å and 2.3737(7) Å, while the In-N
bond distance is 2.068(2) Å. The axial In-O bond lengths are
combined with electron deficient amine BrC
3 atm. of CO . This afforded the urea (BrC
6
H
4
NH(SiMe
3
) under
2.309(2) Å and 2.311(2) Å and give rise to an O(1)-In-O(2) angle
2
6
H
4
NH) CO 8 in 92%
2
of 170.90(6)°.
yield (Table 1, Entry 4). In sharp contrast, addition of excess
pyridine resulted in complete catalysis inhibition.
Figure 1 POV-ray depictions of (a) 2 and (b) 3. C: black, N: blue,
Cl: green, O: red, Si: light-pink, In: red-brown.
Figure 2 POV-ray depiction of 4. C: black, N: blue, Cl: green, O:
red, Si: light-pink, In: red-brown.
2
The reactivity of these species with CO was explored.
While compound 1 showed no reaction, presumably a result of
steric congestion and reduced Lewis acidity at indium, treatment
6 2
of a benzene-d solution of 2 with CO resulted in its complete
1
consumption in 30 minutes. Three new H NMR resonances with
an intensity ratio of 2:1:1 were observed at 0.39 ppm, 0.36 ppm
and -0.14 ppm. One product, 4, was isolated and shown to give
1
rise to the H NMR signals at 0.39 ppm and 0.36 ppm while the
signal -0.14 ppm was confirmed to arise from the generation of
Me
Crystallographic data for 4 confirmed the formulation as the two-
fold symmetric dimeric species [(Me Si) N)InCl(-OSiMe )] in
which siloxy groups bridge two pseudo-tetrahedral indium centers
Figure 2) with In-O bond distances of 2.1172(9) and 2.1134(9) Å.
The corresponding In-Cl and In–N distances were found to be
3
SiNCO by comparison with an authentic sample.
3
2
3 2
(
2
.3487(4) Å and 2.038(1) Å, respectively.
Repetition of the reaction with 13CO
revealed the
2
1
3
generation of a C NMR resonance at 172.3 ppm on mixing. This
peak, attributed to a reaction intermediate, disappeared in about
30 minutes (see SI) and was replaced with the resonance at 124.3
ppm, corresponding to Me
thought to arise from CO
3
SiNCO. The observed intermediate is
insertion into one of the In-N bonds.
2
Scheme 2 Stoichiometric reactions of 2 and 3 with CO .
2
Subsequent silyl migration to oxygen liberates Me
yields the monomeric (Me Si) NInCl(OSiMe ), which rapidly
dimerizes to the siloxy-bridged species (Scheme 2).
Interestingly, further reaction of the remaining amide ligand on 4
is not seen, presumably because of the reduced Lewis acidity in
comparison to 2. The role of Lewis acidity at indium was further
3
SiNCO and
In testing the scope of this catalysis, optimized conditions
were employed. Thus, heating the combination of 2 mol% pyridine
3
2
3
4
and 3 in a 1:1 ratio with C
6
H
5
NH(SiMe
10 °C resulted in a 70% yield of the urea 6 after 24 hours (Table
, Entry 5). In a similar fashion, the arylamines incorporating
3 2
) under CO (3 atm.) at
1
1
electron donating substituents were converted to corresponding
ureas (RNH) CO (R = 4-MeC 7, 2,6-iPr 9, 4-MeOC 10,
,5-(MeO) 11, 4-(C O)C 12, 4-(Me 13, 3,5-Me (2-
N) 14) in yields ranging from 83-99% (Table 1, Entries 6-12).
Generally, these reactions proceeded more rapidly, in 3-12 hours,
although in the case of the sterically hindered amine
supported by the observation that reaction of 3 with CO
proceeded in a directly analogous fashion affording [Cl In(-
OSiMe )] 5 and Me SiNCO.
Having established CO
extension of this reactivity to catalysis was explored. In initial
2
2
6
H
4
2
C
6
H
3
6 4
H
2
3
C
2 6
H
3
H
6 5
6
H
4
2
N)C
H
6 4
2
3
2
3
5 2
C H
2
insertion into In-N bonds, the
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Angewandte Chemie International Edition
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COMMUNICATION
iPr
2
C
6
H
3
NH(SiMe
3
), 36 hours were required. Arylamines,
details). As shown above, 3 reacts with CO
Me SiNCO. In the presence of pyridine, splitting of the dimer to
give the monomeric species Me SiOInCl (py) A•py is exothermic
by 4.6 kcal/mol. The subsequent reaction with C NH(SiMe ) to
generate (Me Si) O and (C NH)InCl (py) B•py is also favorable
by 6.7 kcal/mol, and the latter is believed to be the catalytically
active species. The initial reaction with CO is slightly endothermic
,affording the corresponding heterocyclic ureas, (2.0 kcal/mol), but a rapid rearrangement affords the O,O-bound
7 and 18 in 70% yield and 73 % yield, respectively, after 12 hours carbamate (C NHCO )InCl (py) C•py, which is 12.5 kcal/mol
Table 1, Entry 16-17). The alkylamines tBuNH(SiMe ) and lower in energy than the starting materials. The initial step is
) afforded the corresponding ureas 19 and 20 analogous to the insertion of CO into the In-P bond in
((iPr P) N)
InCl described by Kemp et al.[24] Coordination of
silylamine to C•py is weakly endothermic, however the
subsequent silyl migration to liberate C NHCO SiMe and
2
to give 5 and
incorporating electron withdrawing substituents were also
converted to the corresponding ureas (RNH) CO (R = 3-(CF )C
8), respectively (Table 1, Entries 13-
5), although these reactions proceeded more slowly, requiring
8 hours to achieve yields of 73-88%. This procedure was also
3
2
3
H
6 4
3
2
1
1
4
5, 4-ClC H N 16, 4-BrC H
6 4 6 4
6
H
5
3
3
2
6
H
5
2
applicable
to
the
diamines
C
10
H
6
(NH(SiMe
3
))
2
and
2
C
6
H
4
(NH(SiMe ))
3 2
1
(
6
H
5
2
2
3
C
6
H
5
CH
2
NH(SiMe
3
2
in quantitative yield after 12 and 3 hours, respectively (Table 1,
Entries 18-19). Trials with the amine 4-MeOC NH(SiPh
showed no reaction, confirming steric demands on silicon inhibit
the reaction (Table 1, Entry 20), while 4-MeOC NH showed no
reaction, affirming the role of the silyl group in the reduction of
CO (Table 1, Entry 21). This protocol could also be used to
perform urea synthesis on gram-scale. In this fashion, 1.1 g of
each of C NH(SiMe ) and tBuNH(SiMe ) were converted to
2
2
2
6
H
4
3
)
6
H
5
2
3
6
H
4
2
regenerate B•py is rate determining, with a barrier of 25.4
kcal/mol. This latter barrier accounts for the required reaction
temperature of 110 °C. Subsequent reaction of the free silyl-
carbamate with silylamine was demonstrated via experiments
2
6
H
5
3
3
6 5 2
generating the asymmetric urea (C H CH NH)CO(HNtBu) (see SI).
ureas 6 and 19 in 96% and 99% yields, respectively. Experiments
with reduced catalyst loading (0.05 mol%) were used to efficiently
provide ureas 6 and 19 on gram scales (Table 1, Entries 22-23).
Similarly, this protocol was used to readily prepare the 13C-labeled
Similar reactions affording urea and hexamethyldisiloxane have
been described in the works of Holmes and co-workers[9] and
Knausz et al.[25]
ureas 13C-7* and 13C-20* from 13CO
.
2
Table 1 Catalytic formation of ureas
No. Amine Substrate
cat.
t
Conv Prod.
mol% (h) (%)
Urea
a
b
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
C
6
H
5
NH(SiMe
3
)
5
5
20
50
6
7
a
a
b
b
b
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
b
b
c
c
4-MeC NH(SiMe
6
H
4
3
)
)
)
24 99
48 <1
48 92
4-BrC
4-BrC
6
H
H
4
NH(SiMe
NH(SiMe
3
5
6
4
3
5
8
C
6
H
5
NH(SiMe
4-MeC NH(SiMe
2,6-iPr
4-MeOC
3,5-(MeO)
4-(C O)C
4-(Me N)C
3,5-Me (2-C
)C
3
)
2
24
12
36
12
12
12
3
70
96
90
98
83
99
99
99
73
78
88
70
73
99
99
<1
<1
79
92
6
6
H
4
3
)
2
7
2
C
6
H
3
NH(SiMe
NH(SiMe
NH(SiMe
3
)
2
9
6
H
4
3
)
2
10
11
12
13
14
15
16
8
2
C
6
H
3
3
)
2
0
1
2
3
4
5
6
7
8
9
0
1
2
3
H
6 5
6
H
4
NH(SiMe
3
)
2
2
6 4
H NH(SiMe
3
)
2
2
5
H
2
N)NH(SiMe
3
)
2
12
48
48
48
12
12
12
3
3-(CF
3
6
H
4
NH(SiMe
NH(SiMe
NH(SiMe
(NH(SiMe ))
(NH(SiMe ))
3
)
2
4-ClC
6
H
4
3
)
2
4-BrC
6
H
4
3
)
2
C
C
10
H
6
3
2
2
17
18
19
20
Scheme 3 Proposed mechanism for the indium catalyzed
synthesis of ureas and computed reaction profile (values are
enthalpy, given in kcal/mol).
6
H
4
3
2
2
tBuNH(SiMe
3
)
2
C
6
H
5
CH NH(SiMe
2
3
)
2
4-MeOC
4-MeOC
6
H
H
4
NH(SiPh
NH
3
)
2
12
12
90
48
In conclusion, we have demonstrated the stoichiometric
reactions of indium-amides with CO and shown that these can
2
be exploited to catalytically prepare a series of ureas. This
strategy offers a synthetic pathway that avoids use of phosgene
6
4
2
2
C
6
H
5
NH(SiMe
3
)
0.05
0.05
6
2
tBuNH(SiMe
3
)
19
a
b
1
no pyridine added. NMR yield determined by integration of H
precursors and instead employs CO
2
, and is suitable for a wide
c
NMR spectra. isolated yield.
range of aryl and alkyl ureas using very low catalyst loadings. Our
interest in main group catalysts for the utilization of CO
to motivate our research efforts.
2
continues
The mechanism of catalysis for the formation of 6 as a
model example was considered computationally (see SI for
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Angewandte Chemie International Edition
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COMMUNICATION
[
[
14] (a) F. Shi, Y. Deng, T. SiMa, J. Peng, Y. Gu, B. Qiao, Angew. Chem.
Int. Ed. 2003, 42, 3257-3260; (b) M. Tamura, K. Ito, Y. Nakagawa, K.
Tomishige, J. Catal. 2016, 343, 75-85.
15] (a) D. W. Stephan, G. Erker, Chem. Sci. 2014, 5, 2625-2641; (b) F.-G.
Fontaine, D. W. Stephan, Curr. Opin. Green Sust. Chem. 2017, 3, 28-
32.
16] C. M. Mömming, E. Otten, G. Kehr, R. Fröhlich, S. Grimme, D. W.
Stephan, G. Erker, Angew. Chem. Int. Ed. 2009, 48, 6643-6646.
17] (a) G. Ménard, D. W. Stephan, J. Am. Chem. Soc. 2010, 132, 1796-
Acknowledgements
The authors gratefully acknowledge the financial support of
the NSERC of Canada. DWS is also grateful for the award of a
Canada Research Chair and an Einstein Fellowship at TU Berlin.
The computational work was made possible by the facilities at
SHARCNET and Compute/Calcul Canada. ARJ is grateful for the
award of a Banting Fellowship. Dr. S. Dastgir is thanked for helpful
discussion.
[
[
1
797; (b) M. A. Dureen, D. W. Stephan, J. Am. Chem. Soc. 2010, 132,
13559-13568; (c) G. Ménard, D. W. Stephan, Angew. Chem. Int. Ed.
011, 50, 8396-8399; (d) I. Peuser, R. C. Neu, X. Zhao, M. Ulrich, B.
2
Schirmer, J. A. Tannert, G. Kehr, R. Fröhlich, S. Grimme, G. Erker, D.
W. Stephan, Chem. Eur. J. 2011, 17, 9640-9650; (e) K. Takeuchi, D.
W. Stephan, Chem. Commun. 2012, 48, 11304-11306; (f) R. C. Neu, G.
Ménard, D. W. Stephan, Dalton Trans. 2012, 41, 9016-9018; (g) L. J.
Hounjet, C. B. Caputo, D. W. Stephan, Angew. Chem. Int. Ed. 2012,
51, 4714-4717; (h) M. J. Sgro, J. Dömer, D. W. Stephan, Chem.
Commun. 2012, 48, 7253-7255; (i) G. Ménard, D. W. Stephan, Dalton
Trans. 2013, 42, 5447-5453; (j) G. Ménard, T. M. Gilbert, J. A.
Hatnean, A. Kraft, I. Krossing, D. W. Stephan, Organometallics 2013,
32, 4416-4422; (k) T. Wang, D. W. Stephan, Chem. Eur. J. 2014, 20,
3036-3039; (l) T. Wang, D. W. Stephan, Chem. Commun. 2014, 50,
7007-7010; (m) D. Voicu, M. Abolhasani, R. Choueiri, G. Lestari, C.
Seiler, G. Ménard, J. Greener, A. Guenther, D. W. Stephan, E.
Kumacheva, J. Am. Chem. Soc. 2014, 136, 3875-3880; (n) J. J. Chi, T.
C. Johnstone, D. Voicu, P. Mehlmann, F. Dielmann, E. Kumacheva, D.
W. Stephan, Chem. Sci. 2017, 8, 3270-3275.
Keywords: indium • main group catalysis • urea • CO
2
[
1]
(a) P. Adams, F. A. Baron, Chem. Rev. 1965, 65, 567-602; (b) A. Basch,
B. Zvilichovsky, B. Hirshmann, M. Lewin, J. Polym. Sci. 1979, 17, 27-
3
7; (c) E. V. Glebova, I. A. Golubeva, T. P. Vishnyakova, Russ. Chem.
Rev. 1985, 54, 249-261; (d) P. Lam, P. Jadhav, C. Eyermann, C. Hodge,
Y. Ru, L. Bacheler, J. Meek, M. Otto, M. Rayner, Y. Wong, Science
1
994, 263, 380-384; (e) P. Y. S. Lam, Y. Ru, P. K. Jadhav, P. E. Aldrich,
G. V. DeLucca, C. J. Eyermann, C.-H. Chang, G. Emmett, E. R. Holler,
W. F. Daneker, L. Li, P. N. Confalone, R. J. McHugh, Q. Han, R. Li, J.
A. Markwalder, S. P. Seitz, T. R. Sharpe, L. T. Bacheler, M. M. Rayner,
R. M. Klabe, L. Shum, D. L. Winslow, D. M. Kornhauser, D. A.
Jackson, S. Erickson-Viitanen, C. N. Hodge, J. Med. Chem. 1996, 39,
3
514-3525; (f) T. W. Greene, P. G. M. Wuts, in Protective Groups in
Organic Synthesis, John Wiley & Sons, Inc., 2002, pp. 494-653; (g) T.
I. Todorov, Y. Yamaguchi, M. D. Morris, Anal. Chem. 2003, 75, 1837- [18] R. Dobrovetsky, D. W. Stephan, Angew. Chem. Int. Ed. 2013, 52, 2516-
1
843; (h) A. Abad, J. Lloveras, A. Michelena, Field Crops Res. 2004,
2519.
8
7, 257-269; (i) M. Frezza, S. Castang, J. Estephane, L. Soulère, C. [19] (a) A. E. Ashley, A. L. Thompson, D. O'Hare, Angew. Chem. Int. Ed.
Deshayes, B. Chantegrel, W. Nasser, Y. Queneau, S. Reverchon, A.
Doutheau, Bioorg. Med. Chem. 2006, 14, 4781-4791; (j) R. Jayakumar,
2009, 48, 9839-9843; (b) A. E. Ashley, D. O'Hare, Top. Curr. Chem.
2013, 334, 191-217.
S. Nanjundan, M. Prabaharan, Reactive and Functional Polymers 2006, [20] A. Berkefeld, W. E. Piers, M. Parvez, J. Am. Chem. Soc. 2010, 132,
6, 299-314; (k) E. Quaranta, M. Aresta, in Carbon Dioxide as 10660-10661.
Chemical Feedstock, Wiley-VCH Verlag GmbH & Co. KGaA, 2010, [21] (a) J. Boudreau, M. A. Courtemanche, F. G. Fontaine, Chem. Commun.
6
pp. 121-167.
2011, 47, 11131-11133; (b) M. A. Courtemanche, J. Larouche, M. A.
Legare, W. H. Bi, L. Maron, F. G. Fontaine, Organometallics 2013, 32,
6804-6811; (c) M. A. Courtemanche, M. A. Legare, L. Maron, F. G.
Fontaine, J. Am. Chem. Soc. 2013, 135, 9326-9329; (d) M. A.
Courtemanche, M. A. Legare, L. Maron, F. G. Fontaine, J. Am. Chem.
Soc. 2014, 136, 10708-10717; (e) F. G. Fontaine, M. A. Courtemanche,
M. A. Legare, Chem. Eur. J. 2014, 20, 2990-2996.
[
2]
(a) M. J. Burk, J. G. Allen, J. Org. Chem. 1997, 62, 7054−7057; (b) Y.
Matsumura, T. Maki, Y. Satoh, Tetrahedron Lett. 1997, 38,
8
5
879−8882; (c) P. Gogoi, D. Konwar, Tetrahedron Lett. 2007, 48,
31−533.
[
[
3]
4]
(a) T. Curtius, J. Prakt. Chem. 1894, 50, 275−294; (b) E. Wilhelm, R.
Battino, Chem. Rev. 1973, 73, 1-9; (c) E. F. V. Scriven, K. Turnbull,
Chem. Rev. 1988, 88, 297−368.
(a) J. S. Nowick, N. A. Powell, T. M. Nguyen, G. Noronha, J. Org.
Chem. 1992, 57, 7364−7366; (b) P. Majer, R. S. Randad, J. Org. Chem.
[22] Even though 3 was shown to have 2 THF molecules bound to indium
in the solid state crystal structure, 1H NMR and EA data suggest the
presence of one molecule of THF in the bulk sample.
1
994, 59, 1937−1938; (c) R. A. Batey, V. Santhakumar, C. Yoshina- [23] (a) K. R. M.A. Petrie, H. Hope, P. P. Power, Bull. Soc. Chim. Fr. 1993,
Ishii, S. D. Taylor, Tetrahedron Lett. 1998, 39, 6267−6270; (d) Y.
Patil-Sen, S. R. Dennison, T. J. Snape, Bioorg. Med. Chem. 2016, 24,
130, 851-855; (b) M. Yarema, M. V. Kovalenko, Chem. Mat. 2013, 25,
1788-1792; (c) Y. Yamashita, Y. Saito, T. Imaizumi, S. Kobayashi,
Chem. Sci. 2014, 5, 3958-3962.
4
241-4245; (e) M. Blain, H. Yau, L. Jean-Gérard, R. Auvergne, D.
Benazet, P. R. Schreiner, S. Caillol, B. Andrioletti, ChemSusChem [24] D. A. Dickie, M. T. Barker, M. A. Land, K. E. Hughes, J. A. Clyburne,
016, 9, 2269-2272; (f) C. M. Sanabria, M. T. do Casal, R. B. A. de
R. A. Kemp, Inorg. Chem. 2015, 54, 11121-11126.
Souza, L. C. S. de Aguiar, M. C. S. de Mattos, Synthesis 2017, 49, [25] D. Knausz, A. Meszticzky, L. Szakacs, B. Csakvari, K. Ujszaszy, J.
2
1
1
648-1654; (g) B. Lin, R. M. Waymouth, J. Am. Chem. Soc. 2017, 139,
645-1652.
Organomet. Chem. 1983, 256, 11-21.
[
[
5] E. V. Vinogradova, B. P. Fors, S. L. Buchwald, J. Am. Chem. Soc. 2012,
34, 11132-11135.
(a) J. H. Park, J. C. Yoon, Y. K. Chung, Adv. Synth. Catal. 2009, 351,
233-1237; (b) L. Zhang, A. K. Darko, J. I. Johns, L. McElwee-White,
1
6]
1
Eur. J. Org. Chem. 2011, 2011, 6261-6268.
[
[
[
[
7]
8]
9]
N. Yamazaki, F. Higashi, T. Iguchi, Tetrahedron Lett. 1974, 15, 1191-
1
194.
H. Ogura, K. Takeda, R. Tokue, T. Kobayashi, Synthesis 1978, 1978,
94-396.
3
M. J. Fuchter, C. J. Smith, M. W. S. Tsang, A. Boyer, S. Saubern, J. H.
Ryan, A. B. Holmes, Chem. Commun. 2008, 2152-2154.
10] (a) K. Kraushaar, D. Schmidt, A. Schwarzer, E. Kroke, Adv. Inorg.
Chem. 2014, 66, 117-162 ; (b) M. A. Pigalevaa, I. V. Elmanovicha, M.
N. Temnikov, M. O. Gallyamova, A. M. Muzafarov, Polym. Sci. Ser.
B 2016, 58, 235-270.
[
[
11] M. T. Zoeckler, R. M. Laine, J. Org. Chem. 1983, 48, 2539-2543.
12] F. Shi, Q. Zhang, Y. Ma, Y. He, Y. Deng, J. Am. Chem. Soc. 2005, 127,
4
182-4183.
13] A. Ion, V. Parvulescu, P. Jacobs, D. D. Vos, Green Chem. 2007, 9, 158-
61.
[
1
This article is protected by copyright. All rights reserved.

Angewandte Chemie International Edition
10.1002/anie.201708921
COMMUNICATION
TOC Graphic
Layout 1:
COMMUNICATION
Ureas from CO
amides are shown to react
with CO in a stoichiometric
2
: Indium-
Maotong Xu, Andrew R. Jupp and Douglas W.
Stephan*
2
manner and subsequently
shown to catalyse the
conversion of 15 silylamines
Page No. – Page No.
Stoichiometric Stoichiometric Reactions of CO
and Indium-Silylamides and Catalytic Synthesis
of Ureas
2
under CO
corresponding ureas in 70-
9% yields.
2
to give the
9
This article is protected by copyright. All rights reserved.