Carbon Dioxide Based N-Formylation of Amines Catalyzed by Fluoride and Hydroxide Anions

Article abstract of DOI:10.1002/cctc.201601027

We described herein a simple approach for N-formylation with CO₂ and hydrosilane reducing agents. Fluoride and hydroxide salts efficiently catalyzed the reaction, principally through activation of the hydrosilanes, which led to hydrosilane reactivities comparable to those of NaBH₄/LiAlH₄. Consequently, the N-formylation of amines with CO₂ could be achieved at room temperature and atmospheric pressure. The mechanism of these anionic catalysts contrasts that of the currently reported systems, for which activation of CO₂ is the key mechanistic step. Using tetrabutylammonium fluoride as a simple ammonium salt catalyst, the N-formylated products of both aliphatic and aromatic amines could be obtained in excellent yields with high selectivities.

Full text of DOI:10.1002/cctc.201601027

Accepted Article
Title: CO2-based N-formylation of Amines Catalyzed by Fluoride and
Hydroxide Anions
Authors: Martin Hulla, Felix Daniel Bobbink, Shoubhik Das, and Paul J.
Dyson
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10.1002/cctc.201601027
ChemCatChem
CO2-based N-formylation of Amines Catalyzed by Fluoride and
Hydroxide Anions
Martin Hulla, Felix D. Bobbink, Shoubhik Das and Paul J. Dyson*
Abstract: We describe a simple approach for N-formylation with
CO2 and hydrosilane reducing agents. Fluoride and hydroxide salts
efficiently catalyze the reaction, principally via the activation of the
hydrosilanes, leading to hydrosilane reactivities comparable to
NaBH4/LiAlH4. Consequently, N-formylation of amines with CO2
may be achieved at room temperature and atmospheric pressure.
The mechanism of these anionic catalysts contrasts with that of the
currently reported systems, where activation of CO2 is the key
mechanistic step. Using TBAF as a simple ammonium salt catalyst,
N-formylated products of both aliphatic and aromatic amines could
be obtained in excellent yields and with high selectivity.
achieved using hydrogen as the reducing agent,[7] harsh
reaction conditions and poor functional group tolerance led to
the employment of other reducing agents such as hydrosilanes
(Scheme 1a).[3e,4] N-formylation of amines with hydrosilanes
has been achieved with transition metal-based catalysts
(copper[8,9] and iron[10]) and a number of organocatalysts.[11-14]
Carbon dioxide is cheap, non-toxic and renewable (C1)
building block for chemical synthesis. However, CO2 is
thermodynamically and kinetically stable, posing a challenge to
its efficient use in the production of commodity chemicals.[1]
The non-catalytic reduction of CO2 and its subsequent
functionalization can be achieved with stoichiometric amounts
of strong reducing agents such as NaBH4 and LiAlH4.[2]
However, the high cost and low selectivity of these reagents
make them unsuitable for industrial scale chemical synthesis.
Consequently, the development of CO2 activation catalysts for
novel C-C, C-O and C-N bond formation reactions in
combination with milder reducing agents has attracted attention
in recent years.[3]
Among these catalyzed reactions the N-formylation of
amines with CO2 is of particular interest as the resulting
formamides are commonly employed solvents as well as
versatile building blocks in the synthesis of pharmaceuticals
and agrochemicals.[3a,4] On an industrial scale formamides are
prepared from carbon monoxide,[5] which could be replaced
with CO2 in combination with a reducing agent. In drug-related
pharmacokinetic studies employing positron emission
topography, the rapid preparation of 11C labelled drug
molecules is required. Since 11C is generated in a cyclotron in
the form of thermodynamically stable 11CH4 or 11CO2, and the
direct incorporation of CO2 into drug molecules is difficult, its
transformation into 11CH3I or 11CO is frequently required.[6] It
would be advantageous, however, to directly incorporate CO2
into drug and drug-like molecules.
Scheme 1. N-Formylation of amines with CO2 and silane reducing agents. a)
General reaction scheme. b) Known CO2 activation modes for the synthesis
of formoxysilane intermediates on route to N-formylated products. c) New
direct method to the formoxysilane intermediates catalyzed by TBAF and
subsequent N-formylation of amines
Activation of CO2 has been achieved with nitrogen
superbases[11] via Lewis base-Lewis acid (LB-LA) interactions
between the lone pair on the nitrogen and the electropositive
CO2 carbon. In the case of 1,5,7-triazabicyclo[4.4.0]dec-5-ene
(TBD) the interaction is further stabilized by H-bonding between
the auxiliary amine functionality of the base and an oxygen
atom on the CO2. Formation of LB-LA adducts with CO2 and
subsequent N-functionalization of amines was also reported
with N-heterocyclic carbene (NHC) and thiazolium carbene
catalysts.[12] Further improvements were made with 1,3,2-
diazaphospholenes,[13] in which insertion of CO2 into the
phosphorus-hydrogen bond of the catalyst activates the CO2 for
further functionalization (Scheme 1b). Despite these advances,
limitations to the current catalysts exist, e.g. long reaction times
(frequently beyond 24 hours) are required with the carbene
catalysts and over reduction to the N-methylated products is
frequently observed with the 1,3,2-diazaphospholene systems.
Furthermore, increasingly air and moisture sensitive catalysts
are used to achieve more efficient CO2 activation, hindering
their widespread use.
While the N-formylation of amines with CO2 may be
[a]
[b]
M. Hulla, F. D. Bobbink, Prof. Dr. P. J. Dyson Institut des Sciences
et Ingénierie Chimiques, École Polytechnique Fédérale de
Lausanne (EPFL), CH-1015 Lausanne (Switzerland)
E-mail: paul.dyson@epfl.ch
Dr. S. Das
Institut für Organische und Biomolekulare Chemie, Georg-August-
Universität Göttingen, Göttingen, Germany
Supporting information for this article is given via a link at the end of
the document
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10.1002/cctc.201601027
ChemCatChem
We report an alternative approach to the N-formylation
reaction with CO2, based principally on the activation of the
hydrosilane reducing agent, which overcomes the above
mentioned limitations. Using simple fluoride or hydroxide salts
the hydrosilane reducing agent is activated leading to
reactivities comparable to NaBH4/LiAlH4. As such, N-
formylation of amines with CO2 may be rapidly achieved at RT
and atmospheric pressure with cheap, commercially available
catalysts.
The overall catalytic activity of the salt is based on a
combination of the nucleophilicity of the anion and the extent of
the cation-anion interactions in solution. Strong ionic
interactions promote the formation of less nucleophilic ion pairs,
which result in lower catalytic activities. In contrast, large,
sterically hindered cations such as TBA minimize cation-anion
pairing and promote the formation of ‘free’, highly nucleophilic
anions. Note, in a solvent free system 66% conversion of N-
methylaniline is achieved with TBAF and phenylsilane in 2
hours at RT (Table 1, entry 7) while no conversion is observed
with CsF under equivalent conditions. This finding is consistent
with earlier reports on CsF with dimethylphenylsilane that
required 39 hours at elevated temperature for the reaction to
proceed.[16]
Table 1. Optimization of N-formylation reaction conditions using N-
methylaniline as a model substrate.
Entry
Catalyst
Silane
Solvent
T [h]
Yield [%]
1
[BMIm]Cl
[BdMIm]Cl
[BMP]Cl
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
Ph2SiH2
PMHS
-
20
20
20
20
20
20
2
6
2
-
38
47
2
3
-
4
TBAI
-
5
TBAB
-
6
6
TBAC
-
65
66
73
99
25
0
7
TBAF.3H2O
TBAOH.30H2O
TBAF.3H2O
TBAF.3H2O
TBAF.3H2O
TBAF.3H2O
TBAF.3H2O
TBAF.3H2O
TBAF.3H2O
-
-
8
-
-
2
9
6
10
11
12
13
14
15
16
-
6
-
6
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
Pentane
THF
MeCN
DMF
DMF
2
13
67
69
91
55
2
Scheme 2. Proposed reaction mechanism for the N-Formylation reaction. a)
Formation of formoxysilane intermediate. b) Reaction of the formoxysilane
with amines.
2
2
20
TBAF and other fluoride salts are known to interact with
silanes and are frequently employed as catalysts in the
hydrosilane reduction of carbonyls.[17] The reaction proceeds
via nucleophilic attack on the silane and the formation of a
hypervalent silicon intermediate.[17f] Presumably the silicon
hydride in the hypervalent silicon intermediate is able to directly
reduce CO2 via insertion into the polarized Siδ+-Hδ- bond. CO2
insertion into polarized [E]δ+-Hδ- bonds is known for many group
13 and 14 hydrides with examples reported for B,[2a-b,18] Al,[2c,19]
Ga,[20] Ge,[21] Sn[22] and even proposed for silicon.[23] To confirm
this hypothesis we recorded 1H and 19F NMR spectra of
phenylsilane with 10 mol% TBAF (SI). After addition of the salt,
a centered at -0.24 ppm, not present in neat phenylsilane, was
observed. This finding is consistent with the formation of a 5-
coordinate trigonal bipyramidal silicon center with a hydride in
an axial position coupling to two equatorial hydrogen nuclei JH-H
= 4.1Hz. The related doublet was identified by COSY NMR
spectroscopy at 3.64 ppm at slightly lower frequency (0.32
ppm) to the original phenylsilane singlet (see SI). No coupling
to the anion was observed presumably due to rapid anion
exchange in solution at RT.[17f] A number of different CO2
reduction mechanisms are possible by the silicon hydride.
However, while direct CO2 insertion into the polarized Siδ+-Hδ-
bond was previously suggested,[23] and partly supported by the
detection of the hypervalent silicon intermediate, a recent DFT
study of related systems indicates that in the presence of CO2 a
Following the report on 1-butyl-3-methylimidazolium
chloride ([BMIm]Cl)[14] as a catalyst for the N-formylation
reaction of amines with CO2, we decided to investigate the
reactivity of a number of related imidazolium-based salts. It
quickly became apparent to us that the imidazolium cation does
not participate in the reaction. Although the in-situ formation of
NHC carbenes by self-deprotonation is possible with
imidazolium salts,[15] methylation of the acidic C2 position would
inhibit the reaction if carbene formation is necessary for the
reaction. We found that methylation of [BMIm]Cl at the C2
position to afford 1-butyl-2,3-dimethylimidazolium chloride
([BdMIm]Cl), leads to a six times higher reaction rate (Table 1,
entries 1 and 2). In addition, replacement of [BMIm]Cl with 1-
butyl-1-methyl-pyrrolidinium
chloride
([BMP]Cl)
or
tetrabutylammonium chloride (TBAC) further improves the
catalytic activity (Table 1, entries 3 and 6).
For organic chloride salts the reactivity follows the order
[BMIm]Cl < [BdMIm]Cl < [BMP]Cl < TBAC. The highest activity
demonstrated by TBAC, with a benign tetrabutylammonium
cation, indicates that the reaction is driven by the anion with the
cation acting as a non-interacting counter ion. Subsequent
screening of TBA salts revealed a strong anion dependency on
the reaction rate, with I- < Br- < Cl- << F- ~ OH- (Table 1, entries
4-8). Harder, more nucleophilic anions with high affinity for
silicon such as F- and OH- catalyze the reaction much more
efficiently than soft, less nucleophilic anions.
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10.1002/cctc.201601027
ChemCatChem
concerted hydride transfer via an Sn2-type mechanism with a
structurally equivalent 5-coordinate silicon transition state,
followed by reinsertion of a formate anion, is energetically
favoured.[24]
Based on our experimental data and previous
studies,[14,16,23] an alternative reaction mechanism for the N-
formylation of amines with CO2 and hydrosilanes may be
methylation was observed for 2i-2m, whereas p-nitroaniline
(2n) was unreactive under the reaction conditions. Primary
aliphatic amines (2o-2p) afford the corresponding N-
formylamines as the only reaction product within 2 hours.
Polyformylation, observed with NHC carbenes[12a] or [BMIm]Cl
at elevated pressures,[14] was not observed with the TBAF
catalyst.
proposed (Scheme 2), which conforms with
a recently
published theoretical study.[24] In the first step the hydrosilane is
activated via nucleophilic interactions with the anion to form a
hypervalent silicon center (2).[17a-d,f] Hydride transfer from 2 to
CO2 generates the formate anion and a neutral R3SiX (3)
species.[48] Reinsertion of the formate anion into 3 eliminates
the formoxysilane intermediate (4)[16] and regenerates the
catalytically active anion (1). Finally, the formoxysilane 4 reacts
with the amine to afford the desired N-formylated product.
We then investigated the influence of different hydrosilanes
on the reaction rate. More sterically congested hydrosilanes
such as Ph2SiH2 were less effective under the solvent free
conditions employed. With PMHS an N-formylation product was
not observed and, instead, cross-linking of the polymer
occurred. The decrease in the reaction rate observed with
Ph2SiH2 is consistent with the proposed Sn2-type mechanism
for the reaction of hydrosilanes with hydroxide anions[25] and
the calculated Sn2-type mechanism of CO2 reduction with
silicon hydride[24] as well as the formation of an axial silicon
hydride bond. The steric congestion induced by an additional
phenyl ring hinders nucleophilic attack by the anion on the
silicon centre and prevents its activation.
Although the reaction operates under solvent-free
conditions with liquid amines, a solvent is required to solubilize
solid substrates. In THF and MeCN the reaction proceeds at an
equivalent rate to the solvent free system (Table 1, entries 13
and 14). A positive solvent effect is observed in DMF and the
reaction rate is greatly enhanced (Table 1, entry 15). DMF has
been demonstrated to activate hydrosilanes[26] and more
recently proposed to activate CO2 by interacting with the
electrophilic carbon center.[27] However, while these
mechanisms could partially account for the higher activity, in
the presence of far superior nucleophiles, i.e. F- or OH- anions,
such mechanisms seems less likely to significantly improve the
reaction rate. Moreover, the effect cannot be attributed to the
enhanced homogenization of the system as TBAF completely
dissolves in all of the aforementioned solvents. Since DMF and
DMSO were recently reported to catalyze the reaction,[28] albeit
at a much lower rate than the anions (Table 1, entries 15 and
16), and amine activation by the solvent has been proposed, it
is not unreasonable to conclude that a synergistic effect on the
activation of phenylsilane with F- or OH- anions and amine
activation with DMF are responsible for the reaction rate
enhancements observed in DMF. A weak autocatalytic activity
was observed with N-formanilides, presumably due to the
delocalisation of the nitrogen lone pair onto the benzene ring
(see SI).
Scheme 3. Substrate scope for the N-formylation reaction with TBAF.3H2O
catalyst, PhSiH3 and CO2. Reaction conditions: Amine (1 mmol), phenylsilane
(1.2 mmol), CO2 (1 atm), TBAF (10 mol%), 2-7 h at RT. Isolated yields.
Although fluoride activated hydrosilanes are potent
reducing agents of carbonyl, imine and nitrile bonds,[17]
methylacetate and acetyl substituted anilines (2j,2k),
benzophenone imine (2r) and benzophenone hydrazone (2q)
were converted to their corresponding N-formylamines without
the reduction of the unsaturated bond. An unprecedented
selectivity for the reduction of CO2 is observed. Note, 4-acetyl-
N-methylaniline is rapidly reduced to the corresponding alkene
under the same reaction conditions in the absence of CO2
(Scheme 4). The observed selectivity indicates that the
reduction of CO2 and the formation of the formoxysilane
intermediate is extremely fast. The rate limiting step probably
corresponds to the amine formylation step rather than the
reduction of the otherwise unreactive CO2. This suggestion is
consistent with the proposed reaction mechanism, in which the
formylation reaction is essentially uncatalyzed, and because
anilines with electron withdrawing groups are less reactive than
those with electron donating groups. Finally, to demonstrate
that our methodology can be used for the direct preparation of
TBAF was used to evaluate the scope of the N-formylation
reaction with various amines as the reaction between
phenylsilane and TBAOH can be very exothermic and requires
careful control. The reference substrate, N-methylaniline (2e),
was fully converted within 4 hours at RT and the product
isolated in 85% yield. Electron donating substituents on the
aniline ring (2b-2d) accelerate the reaction rate whereas
electron withdrawing groups (2i-2m) retard it. Competing N-
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10.1002/cctc.201601027
ChemCatChem
11C labeled drug molecules we formylated cinacalcet (2t),
setraline (2u) and nortriptyline (2v) as well as the amino acid
ethyl formyl-L-tryptophanate (2s). The N-formylated products
were isolated in good yields (66-84%).
A. Canonica, A. Baiker, Appl. Catal., A 2003, 255, 23–33. e) P.
Munshi, D. J. Heldebrant, E. P. McKoon, P. A. Kelly, C.-C. Tai, P. G.
Jessop, Tetrahedron Lett. 2003, 44, 2725–2727. f) P. G. Jessop, Y.
Hsiao, T. Ikariya, R. Noyori, J. Am. Chem. Soc. 1996, 118, 344–355.
K. Motokura, N. Takahashi, D. Kashiwame, S. Yamaguchi, A. Miyaji,
T. Baba, Catal. Sci. Technol. 2013, 3, 2392–2396.
[8]
[9]
S. Zhang, Q. Mei, H. Liu, H. Liu, Z. Zhang, B. Han, RSC Adv. 2016, 6,
32370–32373.
[10] X. Frogneux, O. Jacquet, T. Cantat, Catal. Sci. Technol. 2014, 4,
1529–1533.
[11] a) C. Das Neves Gomes, O. Jacquet, C. Villiers, P. Thuéry, M.
Ephritikhine, T. Cantat, Angew. Chem. Int. Ed. Engl. 2012, 51, 187–90
b) C. Das Neves Gomes, O. Jacquet, C. Villiers, P. Thuéry, M.
Ephritikhine, T. Cantat, Angew. Chem. 2012, 124, 191–194
[12] a) O. Jacquet, C. Das Neves Gomes, M. Ephritikhine, T. Cantat, J.
Am. Chem. Soc. 2012, 134, 2934–7. b) E. Blondiaux, J. Pouessel, T.
Cantat, Angew. Chem. Int. Ed. Engl. 2014, 53, 12186–90 c) E.
Blondiaux, J. Pouessel, T. Cantat, Angew. Chem. 2014, 126, 12382–
12386. d) S. Das, F. D. Bobbink, G. Laurenczy, P. J. Dyson, Angew.
Chem. Int. Ed. Engl. 2014, 53, 12876–9. e) S. Das, F. D. Bobbink, G.
Laurenczy, P. J. Dyson, Angew. Chem. 2014, 126, 13090–13093. f) S.
N. Riduan, J. Y. Ying, Y. Zhang, J. Catal. 2015, DOI
10.1016/j.jcat.2015.09.009. f) S. Das, F. D. Bobbink, S. Bulut, M.
Scheme 4. Reduction of 4-acetyl-N-methylaniline with PhSiH3 under CO2 or
N2.
In conclusion, we have demonstrated that simple
nucleophilic anions with a high affinity for silicon act as
hydrosilylation catalysts for the reduction of CO2 and the
subsequent N-formylation of amines under ambient conditions.
A mechanism for the catalysts is described based on the
activation of the silane reducing agent followed by the direct
reduction of CO2 with silicon hydride. The system has an
unprecedented selectivity for the reduction of CO2 over the
otherwise more reactive carbonyls, imines and hydrazones.
The novel approach described here should lead to the
development of more active catalysts for the reductive
functionalization of CO2 in the future.
Soudani, P. J. Dyson, Chem. Commun.
2016, DOI
10.1039/c5cc08741d.
[13] a) C. C. Chong, R. Kinjo, Angew. Chem. Int. Ed. 2015, 54, 12116–
12120. b) C. C. Chong, R. Kinjo, Angew. Chem. 2015, 127, 12284–
12288.
[14] L. Hao, Y. Zhao, B. Yu, Z. Yang, H. Zhang, B. Han, X. Gao, Z. Liu,
ACS Catal. 2015, 5, 4989–4993.
[15] a) G. Gurau, H. Rodríguez, S. P. Kelley, P. Janiczek, R. S. Kalb, R. D.
Rogers, Angew. Chem. Int. Ed. Engl. 2011, 50, 12024–6. b) G. Gurau,
H. Rodríguez, S. P. Kelley, P. Janiczek, R. S. Kalb, R. D. Rogers,
Angew. Chem. 2011, 123, 12230–12232. c) A. K. L. Yuen, A. F.
Masters, T. Maschmeyer, Catal. Today 2013, 200, 9–16.
[16] K. Motokura, M. Naijo, S. Yamaguchi, A. Miyaji, T. Baba, Chem. Lett.
2015, 44, 1217–1219.
ACKNOWLEDGMENT
We thank Bastien L. Roulier for his technical assistance and
the Fondation Claude et Juliana (M.H.) and the Swiss
Competence Centre for Energy Research (F.D.B.) for financial
support.
[17] a) M. Fujita, T. Hiyama, J. Org. Chem. 1988, 53, 5405–5415. b) M. D.
Drew, N. J. Lawrence, W. Watson, S. A. Bowles, Tetrahedron Lett.
1997, 38, 5857–5860. c) Y. Kobayashi, E. Takahisa, M. Nakano, K.
Watatani, Tetrahedron 1997, 53, 1627–1634. d) M. Drew, N.
Lawrence, D. Fontaine, L. Sehkri, S. Bowles, W. Watson, Synlett
1997, 1997, 989–991. e) K. Revunova, G. I. Nikonov, Dalton Trans.
2015, 44, 840–66. f) K. Revunova, G. I. Nikonov, Chem. - Eur. J.
2014, 20, 839–45.
[1]
[2]
Aresta, M. Carbon Dioxide as Chemical Feedstock; Wiley-VCH Verlag
GmBh, Weinheim; 2010.
a) R. F. Nystrom, W. H. Yanko, W. Brown, J. Am. Chem. Soc. 1948,
70, 441–441. b) T. Wartik, R. K. Pearson, J. Am. Chem. Soc. 1955,
77, 1075–1075. c) I. Knopf, C. C. Cummins, Organometallics 2015,
34, 1601–1603.
[18] a) K. Fujiwara, S. Yasuda, T. Mizuta, Organometallics 2014, 33,
6692–6695. b) A. Berkefeld, W. E. Piers, M. Parvez, J. Am. Chem.
Soc. 2010, 132, 10660–1.
[19] a) G. Ménard, D. W. Stephan, Dalton Trans. 2013, 42, 5447–53. b) P.-
C. Kuo, I.-C. Chen, J.-C. Chang, M.-T. Lee, C.-H. Hu, C.-H. Hung, H.
Lee, J.-H. Huang, Eur. J. Inorg. Chem. 2004, 2004, 4898–4906.
[20] a) J. A. B. Abdalla, I. M. Riddlestone, R. Tirfoin, S. Aldridge, Angew.
Chem. Int. Ed. Engl. 2015, 54, 5098–102. b) J. A. B. Abdalla, I. M.
Riddlestone, R. Tirfoin, S. Aldridge, Angew. Chem. 2015, 127, 5187–
5191.
[3]
a) J. Klankermayer, S. Wesselbaum, K. Beydoun, W. Leitner, Angew.
Chem. 2016, 128, 7416–7467. b) J. Klankermayer, S. Wesselbaum,
K. Beydoun, W. Leitner, Angew. Chem. Int. Ed. 2016, DOI
10.1002/anie.201507458. c) Q. Liu, L. Wu, R. Jackstell, M. Beller, Nat.
Commun. 2015, 6, 5933. d) C. Maeda, Y. Miyazaki, T. Ema, Catal.
Sci. Technol. 2014, 4, 1482. e) F. J. Fernández-Alvarez, A. M. Aitani,
L. A. Oro, Catal. Sci. Technol. 2014, 4, 611–624. f) K. Huang, C.-L.
Sun, Z.-J. Shi, Chem. Soc. Rev. 2011, 40, 2435–52. g) M. Liu, T. Qin,
Q. Zhang, C. Fang, Y. Fu, B.-L. Lin, Sci. China: Chem. 2015, 58,
1524–1531.
[21] A. Jana, D. Ghoshal, H. W. Roesky, I. Objartel, G. Schwab, D. Stalke,
J. Am. Chem. Soc. 2009, 131, 1288–93.
[22] a) A. Jana, H. W. Roesky, C. Schulzke, A. Döring, Angew. Chem. Int.
Ed. Engl. 2009, 48, 1106–9. b) A. Jana, H. W. Roesky, C. Schulzke,
A. Döring, Angew. Chem. 2009, 121, 1126–1129. c) G. Albertin, S.
Antoniutti, J. Castro, S. García-Fontán, G. Zanardo, Organometallics
2007, 26, 2918–2930.
[4]
[5]
A. Tlili, E. Blondiaux, X. Frogneux, T. Cantat, Green Chem. 2015, 17,
157–168.
H. Bipp, Hansjörg; Kieczka, Ullmann’s Encyclopedia of Industrial
Chemistry, Wiley-VCH Verlag GmbH
Germany, 2000.
& Co. KGaA, Weinheim,
[23] P. Arya, J. Boyer, R. J. P. Corriu, G. F. Lanneau, M. Perrot, J.
Organomet. Chem. 1988, 346, C11–C14.
[6]
[7]
F. Liger, T. Eijsbouts, F. Cadarossanesaib, C. Tourvieille, D. Le Bars,
T. Billard, Eur. J. Org. Chem. 2015, 2015, 6434–6438.
[24] Q. Zhou, Y. Li, J. Am. Chem. Soc. 2015, 137, 10182–9.
[25] a) L. Kaplan, K. E. Wilzbach, J. Am. Chem. Soc. 1955, 77, 1297–
1302. b) L. H. Sommer, O. F. Bennett, P. G. Campbell, D. R.
Weyenberg, J. Am. Chem. Soc. 1957, 79, 3295–3296. c) J. E. Baines,
C. Eaborn, J. Chem. Soc. 1955, 4023.
a) L. Zhang, Z. Han, X. Zhao, Z. Wang, K. Ding, Angew. Chem. Int.
Ed. 2015, 54, 6186–6189. b) L. Zhang, Z. Han, X. Zhao, Z. Wang, K.
Ding, Angew. Chem. 2015, 127, 6284–6287. c) C. Ziebart, C.
Federsel, P. Anbarasan, R. Jackstell, W. Baumann, A. Spannenberg,
M. Beller, J. Am. Chem. Soc. 2012, 134, 20701–20704. d) L. Schmid,
[26] S. Kobayashi, M. Yasuda, I. Hachiya, Chem. Lett. 1996, 407–408.
This article is protected by copyright. All rights reserved.

10.1002/cctc.201601027
ChemCatChem
[27] L. Wang, L. Lin, G. Zhang, K. Kodama, M. Yasutake, T. Hirose, Chem.
Commun. 2014, 50, 14813–6.
[28] H. Lv, Q. Xing, C. Yue, Z. Lei, F. Li, Chem. Commun. 2016, 52, 6545–
8.
COMMUNICATION
Martin Hulla, Felix D. Bobbink, Shoubhik
Das and Paul J. Dyson*
Page No. – Page No.
CO2-based N-formylation of Amines
Catalyzed by Fluoride and Hydroxide
Anions
Keywords: Carbon dioxide, organocatalysis, sustainable chemistry, reduction,
silanes
This article is protected by copyright. All rights reserved.