Chemoselective Supported Ionic-Liquid-Phase (SILP) Aldehyde Hydrogenation Catalyzed by an Fe(II) PNP Pincer Complex

Article abstract of DOI:10.1021/acscatal.7b04149

A base-tolerant supported ionic-liquid-phase (SILP) system containing a well-defined hydride Fe(II) PNP pincer complex has been prepared, structurally characterized, and used as catalyst in the hydrogenation of aldehydes to alcohols. The new SILP catalyst, with the optimum pore filling, was highly active exhibiting TONs and TOFs of up to 1000 and 4000 h^-1, respectively, under mild conditions (25 °C, 10-50 bar H₂ pressure) without significant leaching of both the complex and the IL.

Full text of DOI:10.1021/acscatal.7b04149

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Letter
Chemoselective Supported Ionic Liquid Phase (SILP) Aldehyde
Hydrogenation Catalyzed by an Fe(II) PNP Pincer Complex
Julian Brünig, Zita Csendes, Stefan Weber, Nikolaus Gorgas, Roland Bittner,
Andreas Limbeck, Katharina Bica, Helmuth Hoffmann, and Karl Kirchner
ACS Catal., Just Accepted Manuscript • DOI: 10.1021/acscatal.7b04149 • Publication Date (Web): 02 Jan 2018
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ACS Catalysis
Chemoselective Supported Ionic Liquid Phase (SILP) Aldehyde
Hydrogenation Catalyzed by an Fe(II) PNP Pincer Complex
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,‡
1,‡
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Julian Brünig, Zita Csendes, Stefan Weber, Nikolaus Gorgas, Roland W. Bittner, Andreas
2
Limbeck,
1
, 1
,1
Katharina Bica, Helmuth Hoffmann,* and Karl Kirchner*
1
2
Institute of Applied Synthetic Chemistry and Institute of Chemical Technologies and Analytics, Vienna University
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of Technology, Getreidemarkt 9, A-1060 Vienna, AUSTRIA).
ABSTRACT: A base-tolerant supported ionic liquid phase (SILP) system contain-
ing a well-defined hydride Fe(II) PNP pincer complex has been prepared, struc-
turally characterized and used as catalyst in the hydrogenation of aldehydes to
alcohols. The new SILP catalyst, with the optimum pore filling, was highly active
-
1
exhibiting TONs and TOFs of up to 1000 and 4000 h , respectively, under mild
o
conditions (25 C, 10-50 bar H pressure) without significant leaching of both the
2
complex and the IL.
KEYWORDS: Hydrogenation, aldehydes, iron, pincer complexes, supported ionic liquid phase
The catalytic hydrogenation of carbonyl compounds is
an environmentally benign and economic method to
obtain alcohols which are a valuable feedstock for a large
lysts reported to date. The remarkable substrate selectivi-
ty was recently explained by the relative stability of alkox-
ide intermediates formed upon aldehyde insertion into a
Fe-H bond of 2 based on state-of the-art DFT calcula-
1
number of fine and bulk chemicals. Accordingly, many
1
6
highly active homogeneous catalysts based on both pre-
cious and non-precious metals have been developed for
tions.
2,3
this purpose over the years. However, a major issue to
be solved is still selectivity such as hydrogenation of car-
bonyl compounds in the presence of other reducible func-
4
tional groups. In particular, catalysts which exhibit full
selectivity for aldehydes over ketones and/or alkenes are
5
of practical importance for the synthesis of flavors, fra-
5
6
grances and pharmaceuticals. One of the most efficient
chemoselective catalyst for the hydrogenation of alde-
hydes in the presence of ketones is the ruthenium catalyst
[Ru(en)(dppe)(OCOtBu)2] (dppe
=
1,2-bis(diphenyl-
7
phosphino)ethane, developed by Dupau and co-workers.
In recent years, considerable progress has been made in
the development of chemoselective hydrogenation cata-
lysts based on earth abundant, and thus inexpensive, non-
Scheme 1. A New Iron-Based SILP Catalyst.
A major drawback of homogeneous catalysis is the need
for separation of the (often rather toxic) catalysts at the
end of the process. These shortcomings can be eliminated
by direct immobilization of a sensitive homogeneous
catalyst on a support, which often results
8
-11
precious metals.
In particular, iron-based systems
proved to be highly selective for the reduction of alde-
hydes in the presence of other carbonyl moieties and C=C
1
2-15
double bonds.
We recently reported the application of
Me
Me
[Fe(PNP -iPr)(CO)(H)(Br)]
(1)
and
[Fe(PNP
-
in partial or complete loss of activity, since the active
species suffers a modification of its chemical and physical
properties. An alternative benign and efficient approach is
iPr)(CO)(H) ] (2) as catalysts for the chemoselective hy-
2
15
drogenation of aldehydes to yield alcohols. The dihy-
dride complex 2, rapidly formed from 1 in the presence of
the use of supported ionic-liquid phase (SILP) cata-
17,18
H and base, is the key catalyst. These catalysts were
2
lysts,
where a homogeneous catalyst is dissolved in an
found to be among of the most efficient base metal cata-
ionic liquid (IL) and impregnated on a porous support
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Page 2 of 7
-
1
material. The chemical nature of the homogeneous cata-
lyst is preserved, yet dissolved in a separate phase, which
can easily be separated after the reaction, reused or ap-
plied in a continuous flow process with high long-term
OH stretching vibration at 3748 cm was no longer visible
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
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1
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5
5
5
6
in the spectrum of SILP[NTf ] (see ESI). SILP[NTf ] was
2
2
impregnated with 10, 20, 30, and 40 wt% of 1 dissolved in
[bm im][NTf ] producing SILP10, SILP20, SILP30, and
2
2
1
9
stability. SILP catalysts are therefore considered as sus-
tainable catalysts, since they combine the advantages of
heterogeneous and homogeneous catalysis and make use
of minimum amounts of IL/catalyst solutions in a highly
SILP40, respectively. Structural parameters derived from
N adsorption-desorption isotherms showed that the BET
2
surface area and the pore volume decreased after IL func-
tionalization due to the coating of the silica surface and
the closure of micropores and further upon loading with
IL and catalyst due to the filling of the pores (Table 1).
The pore filling degree (α) increases with the IL loading
up to 100% for SILP40. The catalytic performance of the
new SILP materials containing the Fe(II) catalyst 1 was
first investigated in the hydrogenation of 4-
fluorobenzaldehyde to 4-fluorobenzyl alcohol in the pres-
ence of 5 mol% of DBU (1,8-diaza-bicyclo[5.4.0]undec-7-
20
efficient manner. While the SILP concept is particularly
well established for gas phase reactions such as hydro-
formylations and implemented even in large scale, its
application in liquid-liquid biphasic processes poses addi-
tional problems due to ionic liquid and/or catalyst leach-
0
1
2
3
4
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0
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0
21
ing into the organic co-solvent.
In this work, we report on an iron SILP system which
is highly active for the chemoselective hydrogenation of
aldehydes to alcohols (Scheme 1). The pre-catalyst is the
well-defined hydride complex 1 which is dissolved in IL 1-
butyl-2,3-dimethyl-imidazolium
o
ene) as base in n-heptane at 25 C. The results are present-
ed in Table 2. SILP20 was found to have the optimum
pore filling degree catalyz-
bis(trifluoromethylsulfonyl) ([bm im][NTf ]) and applied
2
2
as a thin film coated onto powdered silica as the support.
The silica gel (SG) itself is functionalized with 1,2-
dimethyl-3-(3-trimethoxysilylpropyl)imidazolium-
Table 1. Structural Parameters Calculated from the N
2
Adsorption-Desorption Isotherms.
Sample
BET
Pore
Average
α d
b
surface
volume
pore diam-
(%)
bis(trifluoro-methylsulfonyl) imide ([TMSpm im][NTf ])
2
2
a
3
c
area
(cm /g)
eter
in order to avoid side reactions with the active acidic OH
groups and the iron catalyst and to create an “IL-philic”
surface as protection against IL/catalyst leaching. To the
best of our knowledge, this is the first example of a well-
defined Fe(II) complex containing SILP system for the
chemoselective hydrogenation of aldehydes to afford
alcohols.
2
(
m /g)
303
(nm)
7.2
SG
0.68
0.39
0.23
0.13
SILP[NTf2]
SILP10
240
133
58
4.7
4.5
5.1
19
43
SILP20
SILP30
SILP40
The hydride ligand in 1 as well as the hydride ligands
of the in the in situ generated active catalyst 2 are strongly
basic and thus sensitive to acidic functionalities such as
the H atom in the 2-position of 1,3-dialkylimidazolium
ions and the OH groups of the silica gel. To avoid catalyst
decomposition by these groups, the silica gel was coated
15
0.03
5.2
74
too low to measure
~100
a
b
Calculated by the BET equation. BJH pore desorption
c
d
volume. Desorption average pore diameter. Pore filling
degree (IL volume/pore volume).
with
the
1,2,3-alkylated
imidazolium
chloride
[
TMSpm im][Cl] yielding SILP[Cl]. Subsequently, the
2
ing this reaction most efficiently, while all other SILPs
were found to be less efficient or completely inactive
(Table 2, entries 1-4). No conversion was obtained without
catalyst. Accordingly, we focused on the reactivity of
SILP20. With a catalyst loading of 0.5 mol% under 10 bar
-
chloride ions were exchanged to non-coordinating NTf2
ions resulting in the formation of SILP[NTf ]. This mate-
2
1
3
1
rial was characterized by elemental analysis, C{ H}- and
29
1
Si{ H}-CP-MAS NMR, FT-IR, and N2 adsorption-
desorption techniques.
H pressure, quantitative conversion was reached within
2
From elemental analysis, the nitrogen content yielded
1
7 min (Table 2, entry 2). Increasing the hydrogen pres-
sure to 20 and 50 bar reduced the reaction times to 13 and
min, respectively (Table 2, entries 5 and 6). Lowering
0
.64 mmol [TMSpm im][Cl] per gram of SILP[NTf ] corre-
2 2
2
sponding to a surface coverage of 1.6 molecules per nm .
29
8
1
Si{ H}-CP-MAS NMR spectroscopy confirmed that the
organic moiety is covalently grafted to the silica surface
see Supporting Information). The infrared spectrum of
the catalyst loading to 0.1 mol% at 10 bar H pressure
2
resulted in 85% conversion after 90 min (Table 2, entry 7).
With the same catalyst loading but under
(
SILP[NTf ] also confirmed that free silanol groups of the
2
silica gel reacted with the silanized IL, since the isolated
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1
2
3
4
5
6
7
8
9
a
Table 2. Hydrogenation of 4-Fluorobenzaldehyde with Catalyst 1 under SILP, Homogeneous, and Biphasic Conditions.
H
Me
N
PiPr
2
cat, H2
N
Fe
CO
O
OH
DBU (5 mol%)
N PiPr
2
1
F
o
F
n-heptane, 25 C
Me
Br
b
entry
conditions
S/C
P
time
Yield
(%)
TON
TOF
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
-
1
(
bar)
(min
)
(h )
1
SILP10
SILP20
SILP30
SILP40
SILP20
SILP20
SILP20
SILP20
200
200
200
200
200
200
1000
1000
200
10
10
10
10
20
50
10
50
10
75
17
75
75
13
8
16
>99
7
32
200
14
26
706
11
2
3
4
5
6
7
8
9
3
6
5
>99
>99
85
200
200
850
1000
200
923
1500
567
4000
2000
90
15
6
>99
>99
homogene-
ous
10
biphasic
200
10
12
>99
200
1000
a
Conditions: entry 1: 2 mmol substrate, 1000 mg SILP10 (5 mg 1, 95 mg IL, 900 mg SILP[NTf ]); entry 2,5,6: 2 mmol substrate, 500
2
mg SILP20 (5 mg 1, 95 mg IL, 400 mg SILP[NTf ]); entry 3: 2 mmol substrate, 333 mg SILP30 (5 mg 1, 95 mg IL, 233 mg
2
SILP[NTf ]); entry 4: 2 mmol substrate, 250 mg SILP40 (5 mg 1, 95 mg IL, 150 mg SILP[NTf ]); entry 7,8: 10 mmol substrate, 500
2
2
mg SILP20 (5 mg 1, 95 mg IL, 400 mg SILP[NTf ]); entry 10: 2 mmol substrate, 5 mg 1 dissolved in 255 mg IL; all reactions were
2
o
b
19
1
performed with 2 mL of n-heptane and 5 mol% of DBU at 25 C. Determined by F{ H} NMR spectroscopy.
a hydrogen pressure of 50 bar, quantitative conversion
was already reached after 15 min corresponding to a TON
ing comparable TONs but reduced TOFs. It eliminates,
however, their main drawbacks, i.e., difficult separation
and large amounts of IL, making the SILP catalyst more
sustainable.
-1
and TOF of 1000 and 4000 h , respectively (Table 2, entry
8). After the reaction, the solid SILP20 could be easily
separated from the solution. The liquid reaction mixtures
were analyzed with ICP-MS for iron leaching, yielding in
the worst case merely 0.125±0.038 mol% Fe with respect
to the initial total loading of the iron catalyst. Based on
1
9
1
F{ H} NMR spectroscopy, there was no evidence for
leaching of the IL into the n-heptane solution as no sig-
-
nals of the NTf anion could be detected.
2
For comparison, the reaction was also performed un-
der homogeneous and biphasic reaction conditions with
0
.5 mol% catalyst loading and a hydrogen pressure of 10
bar (Table 2, entries 9 and 10). SILP20 is only slightly less
active than the homogeneous and biphasic systems reach-
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Figure 1. Catalyst Recycling in the Hydrogenation of 4-
Page 4 of 7
industry (Table 3, A14-A20), as well as the challenging
α,β-unsaturated substrate cinnamaldehyde (Table 3, A13)
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
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3
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4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
Fluorobenzaldehyde by Repeated Addition of Aldehyde.
Conditions: 500 mg SILP20, 2 mL n-heptane, 2 mmol
were
not
hydrogenated.
Importantly,
4-
o
substrate, 0.5 mol% 1, 5 mol% DBU, 25 C, 50 bar H .
acetylbenzaldehyde was hydrogenated only at the alde-
hyde moiety (Table 3, A10). This again emphasizes the
high selectivity of the present system.
2
Moreover, it was possible to recycle the catalyst by re-
peated addition of aldehyde after each reaction cycle
In conclusion, we have developed a novel Fe(II) PNP
pincer complex based SILP system, which was fully char-
acterized and used as a hydrogenation catalyst for the
chemoselective hydrogenation of aromatic and aliphatic
(
Figure 1). This procedure was carried out four times eve-
ry 7 minutes and yielded a TON of 1000 and a TOF of 1714.
These results hold great promise for a continuous flow
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
22
operation of this catalytic system.
aldehydes to give alcohols under mild conditions (0.1-0.05
o
mol% catalyst, 25 C, H 50 bar pressure) without signifi-
2
Table 3. Hydrogenation of Aldehydes A1-A20 Catalyzed
cant leaching of the catalyst. The newly developed SILP
system shows high potential as an efficient catalyst under
continuous flow conditions which will be the subject of
future studies in our groups.
a
by Catalyst 1 Under SILP20 Conditions.
ASSOCIATED CONTENT
* Supporting Information
This material is available free of charge via the Internet at
http://pubs.acs.org.
Experimental details of the synthesis of all materials
including solid state C{ H} and Si{ H} NMR spectra
PDF)
1
3
1
29
1
(
AUTHOR INFORMATION
Corresponding Authors
*E-mail: karl.kirchner@tuwien.ac.at
*E-mail: helmuth.hoffmann@tuwien.ac.at.
ORCID
Karl Kirchner: 0000-0003-0872-6159
a
Conditions: 500 mg SILP20, 2 mL n-heptane, 2 mmol sub-
Author Contributions
o
strate, 0.5 mol% 1, 5 mol% DBU, 25 C, 50 bar H , 1 h. Yields
‡
2
These authors contributed equally.
1
were determined by calibrated GC/MS and H NMR spectros-
Notes
copy with mesitylene as internal standard. In all cases yields
The authors declare no competing financial interests.
>98% were observed.
ACKNOWLEDGMENTS
To demonstrate the general applicability of catalyst
JB, ZC, NG and KK thank the Austrian Science Fund (FWF)
for the financial support through projects M 2068-N28 (ZC)
and P 28866-N34 (JB, NG, KK).
SILP20 the scope has been tested with several substrates
as shown in Table 3. The catalytic experiments were con-
ducted in the presence of 0.5 mol% of catalyst at 25°C
under 50 bar hydrogen pressure in the presence of 5
mol% DBU to ensure quantitative conversion for all sub-
strates in a reasonable reaction time (1 h). Under these
reaction conditions, very good results could be obtained
for aromatic and heteroaromatic aldehydes bearing both
electron withdrawing halogen substituents such as F, Cl,
and Br in 4-halobenzaldehydes or electron donating
groups such as OMe in 4-anisaldehyde (Table 3, A1-A5).
High chemoselectivity was achieved with both conjugated
and non-conjugated C=C double bonds. In fact, C=C dou-
ble bonds in aliphatic aldehydes such as citronellal, lyral,
or scentenal, which are used in the flavor and fragrance
REFERENCES
(1) (a) de Vries, J. G.; Elsevier, C. J. Eds. Handbook of Homoge-
neous Hydrogenation; Wiley-VCH: Weinheim, 2007. (b) Dupau,
P. In Organometallics as Catalysts in the Fine Chemical Industry;
Beller, M.; Blaser, H. U. Eds. Springer-Verlag: Berlin, 2012. (c)
Johnson, N. B.; Lennon, I. C.; Moran, P. H.; Ramsden, J. A. Acc.
Chem. Res. 2007, 40, 1291-1299. (d) Dub, P. A.; Ikariya, T. ACS
Catal 2012, 2, 1718-1741.
(2) (a) Blaser, H. U.; Malan, C.; Pugin, B.; Spindler, F.; Steiner,
H.; Studer M. Adv. Synth. Catal. 2003, 345, 103-151. (b) Naud, F.;
Spindler, F.; Rueggeberg, C. J.; Schmidt, A. T.; Blaser, H. U. Org.
Process Res. Dev. 2007, 11, 519-523.
(3) (a) Noyori, R.; Ohkuma, T. Angew. Chem. Int. Ed. 2001, 40,
40-73. (b) Noyori, R. Angew. Chem. Int. Ed. 2013, 52, 79-92.
ACS Paragon Plus Environment

Page 5 of 7
ACS Catalysis
(
4) (a) Noyori, R.; Ohkuma, T. Pure Appl. Chem. 1999, 71, 1493-
Schneider, S. ACS Catal. 2014, 4, 3994-4003. (k) Lagaditis, P. O.;
Sues, P. E.; Sonnenberg, J. E.; Wan, K. Y.; Lough, A. J.; Morris, R.
H. J. Am. Chem. Soc. 2014, 136, 1367–1380. (l) Werkmeister, S.;
Junge, K.; Wendt, B.; Alberico, E.; Jiao, H.; Baumann, W.; Junge,
H.; Gallou, F.; Beller, M. Angew. Chem. Int. Ed. 2014, 53, 8722-
8726. (m) Bertini, F.; Mellone, I.; Ienco, A.; Peruzzini, M.;
Gonsalvi, L. ACS Catal. 2015, 5, 1254-1265. (n) Rivada-
Wheelaghan, O.; Dauth, A.; Leitus, G.; Diskin-Posner, Y.;
Milstein, D: Inorg. Chem. 2015, 54, 4526-4538. (o) Zhang, Y.;
MacIntosh, A. D.; Wong, J. L.; Bielinski, E. A.; Williard, P. G.;
Mercado, B. Q.; Hazari, N.; Bernskoetter, W. H. Chem. Sci. 2015,
6, 4291-4299. (p) Gorgas, N.; Stöger, B.; Veiros, L. F.; Pittenauer,
E.; Allmaier, G.; Kirchner, K. Organometallics 2014, 33, 6905-
6914.
1
2
3
4
5
6
7
8
9
1501. (b) Noyori, R. Angew. Chem. Int. Ed. 2002, 41, 2008-2022. (c)
Ohkuma, H.; Ooka, T.; Ikariya, T.; Noyori, R. J. Am. Chem. Soc.
1995, 117, 10417-10418.
(5) (a) Surburg, H.; Panten, J. Eds. Common Fragrance and Fla-
vor Materials; WILEY-VCH: Weinheim, 2006. (b) Saudan, L. A.
Acc. Chem. Res. 2007, 40, 1309–1319.
(6) Smith, A. B.; Barbosa, J.; Wong, W.; Wood, J. L. J. Am.
Chem. Soc. 1996, 118, 8316-8328.
(7) Bonomo, L.; Kermorvan, L.; Dupau, P. ChemCatChem 2015,
7, 907-910.
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4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
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2
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(8) Bullock, R. M. Ed. Catalysis Without Precious Metals,
Wiley-VCH: Weinheim, 2010.
(9) Mn-catalyzed hydrogenation reactions: (a) Kallmeier, F.;
Irrgang, T.; Dietel, T.; Kempe, R. Angew. Chem. Int. Ed. 2016, 55,
11806-11809. (b) Elangovan, S.; Topf, C.; Fischer, S.; Jiao, H.;
Spannenberg, A.; Baumann, W.; Ludwig, R.; Junge, K.; Beller, M.
J. Am. Chem. Soc. 2016, 138, 8809-8814. (c) Garbe, M.; Junge, K.;
Walker, S.; Wei, Z.; Jiao, H.; Spannenberg, A.; Bachmann, S.;
Scalone, M.; Beller, M. Angew. Chem. Int. Ed. 2017, 56, 11237-11241.
(d) Bruneau-Voisine, A.; Wang, D.; Roisnel, T.; Darcel, C.; Sortais
J.-P. Catal. Commun. 2017, 92, 1-4. (e) Widegren, M. B.; Hark-
ness, G. J.; Slawin, A. M. Z.; Cordes, D. B.; Clarke, M. L. Angew.
Chem. Int. Ed., 2017, 56, 5825-5828. (f) Perez, M.; Elangovan, S.;
Spannenberg, A.; Junge, K.; Beller M. ChemSusChem 2017, 10, 83-
86. (g) Zirakzadeh, A., de Aguiar, S. R. M. M.; Stöger, B.;
Widhalm, M.; Kirchner, K.; ChemCatChem 2017, 9, 1744-1748. (h)
Espinosa-Jalapa, N. A.; Nerush, A.; Shimon, L. J. W.; Leitus, G.;
Avram, L.; Ben-David, Y.; Milstein, D. Chem. Eur. J. 2017, 23,
5934-5938. (i) Elangovan, S.; Garbe, M.; Jiao, H.; Spannenberg,
A.; Junge K.; Beller, M. Angew. Chem. Int. Ed. 2016, 128, 15590-
15594. (j) Bertini, F.; Glatz, M.; Gorgas, N.; Stöger, B.; Peruzzini,
M.; Veiros, L. F.; Kirchner, K.; Gonsalvi, L. Chem. Sci. 2017, 8,
5024-5029. (k) van Putten, R.; Uslamin, E. A.; Garbe, M.; Liu, C.;
Gonzalez-de-Castro, A.; Lutz, M.; Junge, K.; Hensen, E. J. M.;
Beller, M.; Lefort, L.; Pidko, E. A. Angew. Chem. Int. Ed. 2017, 56,
7531-7534.
(11) Roesler, S.; Obenauf, J.; Kempe, R. J. Am. Chem. Soc. 2015,
137, 7998-8001.
(12) Wienhofer, G.; Westerhaus, F. A.; Junge, K.; Ludwig, R.;
Beller, M., Chem. Eur. J. 2013, 19, 7701-7707.
(13) Zell, T.; Ben-David, Y.; Milstein, D. Catal. Sci. Technol.
2015, 5, 822-826.
(14) Mazza, S.; Scopelliti, R.; Hu, X. Organometallics 2015, 34,
1538-1545.
(15) Gorgas, N.; Stöger, B.; Veiros, L. F.; Kirchner, K. ACS Catal.
2016, 6, 2664-2672.
(16) Morello, G. R.; Hopmann, K. H. ACS Catal. 2017, 7, 5847-
5855.
(17) (a) Li, H.; Bhadury, P. S.; Song, B.; Yang, S. RSC Adv. 2012,
2, 12525-12551. (b) Van Doorslaer, C.; Wahlen, J.; Mertens, P.;
Binnemans, K.; De Vos, D. Dalton Trans. 2010, 39, 8377-8390. (c)
Pereira, M. M. A. Curr.Org. Chem. 2012, 16, 1680-1710. (d) Xin, B.;
Hao, J. Chem. Soc. Rev. 2014, 43, 7171-7187. (e) Tunckol, M.; Du-
rand, J.; Serp, P. Carbon 2012, 50, 4303-4334. (f) Giacalone, F.;
Gruttadauria, M. ChemCatChem 2016, 8, 664-684.
(18) Fehrmann, R.; Riisager, A.; Haumann, M. Supported Ionic
Liquids: Fundamentals and Applications, Wiley-VCH, Weinheim,
2014.
(19) (a) Weis, A.; Munoz, M.; Haas, A.; Rietzler, F.; Steinruck,
H.-P.; Haumann, M.; Wasserscheid, P.; Etzold, B. J. M. ACS
Catal. 2016, 6, 2280-2286. (b) Becker, M.; Nicole, B.;
Christiansen, A.; Robert, F.; Fridag, D.; Haumann, M.; Jakuttis,
M.; Schonweiz, A.; Peter, P. W.; Werner, S. US20130289313, 2012.
(c) Franke, R.; Hahn, H. Elements - Quarterly Science Newsletter;
Evonik Industries AG, 2015, 51, 18.
(10) Fe-catalyzed hydrogenation reactions: (a) Federsel, C.;
Boddien, A.; Jackstell, R.; Jennerjahn, R.; Dyson, P. J.; Scopelliti,
R.; Laurenczy, G.; Beller, M. Angew. Chem. Int. Ed. 2010, 49,
9777-9780. (b) Langer, R.; Leitus, G.; Ben-David, Y.; Milstein, D.
Angew. Chem. Int. Ed. Engl. 2011, 50, 2120–2124. (c) Langer, R.;
Iron, M. A.; Konstantinovski, L.; Diskin-Posner, Y.; Leitus, G.;
Ben-David, Y.; Milstein, D. Chem. Eur. J. 2012, 18, 7196–7209. (d)
Ziebart, C.; Federsel, C.; Anbarasan, P.; Jackstell, R.; Baumann,
W.; Spannenberg, A.; Beller, M. J. Am. Chem. Soc. 2012, 134,
(20) Garcia-Verdugo, E.; Altava, B.; Burguete, M. I.; Lozano, P.;
Luis, S. V. Green Chem. 2015, 17, 2693-2713.
(21) For SILP catalysts in gas phase hydroformylations, see: (a)
Mehnert, C. P.; Cook, R. A.; Dispenziere, N. C.; Afeworki, M. J.
Am. Chem. Soc. 2002, 124, 12932-12933. (b) Yang, Y.; Lin, H.;
Deng, C.; She, J.; Yuan, Y. Chem. Lett. 2005, 34, 220-221. (c)
Riisager, A.; Wasserscheid, P.; van Hal, R.; Fehrmann, R. J. Catal.
2003, 219, 452-455. (d) Riisager, A.; Fehrmann, R.; Haumann, M.;
Wasserscheid, P. Eur. J. Inorg. Chem. 2006, 695-706. (e)
Haumann, M.; Dentler, K.; Joni, J.; Riisager, A.; Wasserscheid, P.
Adv. Synth. Catal. 2007, 349, 425-431. (f) Haumann, M.; Jakuttis,
M.; Franke, R.; Schönweiz, A.; Wasserscheid, P. ChemCatChem
2011, 3, 1822-1827. (g) Walter, S.; Spohr, H.; Franke, R.; Hieringer,
W.; Wasserscheid, P.; Haumann, M. ACS Catal 2017, 7, 1035-1044.
20701-20704. (e) Fleischer, S.; Zhou, S.; Junge, K.; Beller, M.
Angew. Chem. Int. Ed. 2013, 52, 5120-5124. (f) Srimani, D.; Diskin-
Posner, Y.; Ben-David, Y.; Milstein, D. Angew. Chem. Int Ed. 2013,
5
2, 14131–14134. (g) Wienhofer, G.; Baseda-Kruger, M.; Ziebart, C.;
Westerhaus, F. A.; Baumann, W.; Jackstell, R.; Junge, K.; Beller,
M. Chem. Comm. 2013, 49, 9089-9091. (h) Bornschein, C.;
Werkmeister, S.; Wendt, B.; Jiao, H.; Alberico, E.; Baumann, W.;
Junge, H.; Junge, K.; Beller, M. Nat. Commun. 2014, 5, 4111. (i)
Chakraborty, S.; Dai, H.; Bhattacharya, P.; Fairweather, N. T.;
Gibson, M. S.; Krause, J. A.; Guan, H. J. Am. Chem. Soc. 2014, 136,
7869-7872. (j) Chakraborty, S.; Lagaditis, P. O.; Förster, M.;
Bielinski, E. A.; Hazari, N.; Holthausen, M. C.; Jones, W. D.;
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(22) (a) Datta, R.; Rydant, J.; Rinker, R. G. J. Catal. 1985, 95,
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202-208. (b) Rony, P. R. J. Catal. 1969, 14, 142-147.
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