Manganese(I)-Catalyzed Enantioselective Hydrogenation of Ketones Using a Defined Chiral PNP Pincer Ligand

Article abstract of DOI:10.1002/anie.201705471

A new chiral manganese PNP pincer complex is described. The asymmetric hydrogenation of several prochiral ketones with molecular hydrogen in the presence of this complex proceeds under mild conditions (30–40 °C, 4 h, 30 bar H₂). Besides high catalytic activity for aromatic substrates, aliphatic ketones are hydrogenated with remarkable selectivity (e.r. up to 92:8). DFT calculations support an outer sphere hydrogenation mechanism as well as the experimentally determined stereochemistry.

Full text of DOI:10.1002/anie.201705471

A Journal of the Gesellschaft Deutscher Chemiker
Angewandte
International Edition Chemie
www.angewandte.org
Accepted Article
Title: Manganese(I)-catalyzed Enantioselective Hydrogenation of
Ketones using a Defined Chiral PNP Pincer Ligand
Authors: Marcel Garbe, Kathrin Junge, Svenja Walker, Zhihong
Wei, Haijun Jiao, Anke Spannenberg, Stephan Bachmann,
Michelangelo Scalone, and Matthias Beller
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.201705471
Angew. Chem. 10.1002/ange.201705471
Link to VoR: http://dx.doi.org/10.1002/anie.201705471
http://dx.doi.org/10.1002/ange.201705471

Angewandte Chemie International Edition
10.1002/anie.201705471
COMMUNICATION
Manganese(I)-catalyzed Enantioselective Hydrogenation of
Ketones using a Defined Chiral PNP Pincer Ligand
[
a]
[a]
[a]
[a]
[a]
[a]
Marcel Garbe , Kathrin Junge , Svenja Walker , Zhihong Wei , Haijun Jiao , Anke Spannenberg ,
[
b]
[b]
[a]
Stephan Bachmann , Michelangelo Scalone and Matthias Beller*
Abstract:
A new chiral manganese PNP pincer complex is
described. Asymmetric hydrogenation of several prochiral ketones
with molecular hydrogen in the presence of this complex proceeds
2
under mild conditions (40 °C, 4 h, 30 bar H ). Besides high catalytic
activity for aromatic substrates, aliphatic ketones are hydrogenated
with remarkable selectivities (er up to 92:8). DFT calculations
support an outer sphere hydrogenation mechanism as well as the
experimentally determined stereochemistry.
Figure 1. Different iron complexes as enantioselective catalysts for the
reduction of prochiral ketones.
In 2016, several seminal works described the use of
manganese-based catalysts for (de)hydrogenation reactions.[
In this respect, the first chiral Mn pincer complex 4 was
11]
Chiral organometallic complexes continue to attract
significant attention from academic and industrial chemists for
the production of enantiomerically pure life science products
such as pharmaceuticals, flavors and fragrances.[1] In fact, today
homogeneous asymmetric hydrogenations constitute a state-of-
the-art technology, which was also awarded with the Nobel Prize
to Noyori and Knowles in 2001.[ 2 ] The first examples of
enantioselective hydrogenations were independently developed
by Knowles[ 3 ] and Horner.[ 4 ] Since then, numerous chiral
introduced by the group of Kirchner for asymmetric transfer
[ 12 ]
hydrogenation of ketones.
Most recently, Clarke and co-
workers published the first asymmetric hydrogenation reaction
by using the cationic complex 5 with a facially coordinating chiral
PNN ligand (Scheme 1).[ 13 ] Remarkably, various aromatic
ketones were reduced with excellent enantioselectivities;
however, no asymmetric reduction was demonstrated for
aliphatic substrates. This is not surprising as aliphatic ketones
are much less explored and enantioselectivities comparable to
aromatic substrates are rare, even using noble metal-based
catalysts.[14] Thus, the development of non-noble metal catalysts
phosphine ligands were developed for
a wide range of
applications.[
5 ]
However, the vast majority of the resulting
catalysts are based on noble metals of the platinum group like
ruthenium, rhodium and iridium as catalytically active centers. In
the last decade, the replacement of these platinum group metals
by earth abundant inexpensive and non-toxic transitions metals
like Cu[ 6 ] and Fe[ 7 ] was intensively studied, especially to
transform prochiral ketones to the corresponding secondary
alcohols. Nevertheless, asymmetric catalytic applications using
non-noble metals are still very limited.
for the asymmetric hydrogenation of aliphatic ketones with high
selectivity remains a highly challenging goal.
An important breakthrough in this area was reported by
Morris and co-workers in 2008 using a dicationic iron complex
2 2
a tetradentate P N
ligand.[ 8 ] Subsequently, catalyst
with
systems with pincer ligands were developed by Morris and
Kirchner (Figure 1).[ 9 ] Notably, all these iron complexes
predominantly hydrogenate aromatic substrates with high
selectivities, while aliphatic ketones gave much lower
enantiomeric ratios. In addition, related chiral complexes with
tetradentate ligands were successfully introduced in the field of
asymmetric transfer hydrogenation.[10]
Scheme
1.
Chiral
Mn
pincer
complexes
for
asymmetric
(transfer)hydrogenation reaction.
Inspired by the recent developments using homogeneous
[
[
a]
b]
Marcel Garbe, Dr. Kathrin Junge, Svenja Walker, Zhihong Wei, Dr.
Haijun Jiao, Dr. Anke Spannenberg, Prof. Dr. Matthias Beller*
Leibniz-Institut für Katalyse e. V. an der Universität Rostock,
Albert-Einstein Straße 29a, Rostock, 18059, Germany
Matthias.Beller@catalysis.de
Dr. Stephan Bachmann, Dr. Michelangelo Scalone
F. Hoffmann-La Roche Ltd, Process Chemistry and Catalysis
CH-4070 Basel, Switzerland
Mn catalysts,[11, 15] we became also interested in Mn-catalyzed
asymmetric hydrogenations of (hetero)aromatic and aliphatic
ketones. To the best of our knowledge, no manganese catalysts
have been described for enantioselective hydrogenations of the
latter compounds.
At the start of our investigations the new chiral pincer
complex
ethyl))amine was obtained in 72 % yield by the reaction of
MnBr(CO) ] with the corresponding ligand (Scheme 2).
6
with bis(2-((2R,5R)-2,5-dimethyl-phospholano-
Supporting information for this article is given via a link at the end of
the document.
[
5
This article is protected by copyright. All rights reserved.

Angewandte Chemie International Edition
10.1002/anie.201705471
COMMUNICATION
3[c]
4
Et
O
50
50
50
50
50
50
30
63
80
89/11
90/10
89/11
79/21
92/08
90/10
90/10
2
Toluene
t-AmylOH
EtOH
5[c]
6
>99
24
7
i-PrOH
72
5
Scheme 2. Synthesis of 6 by using [MnBr(CO) ] as metal precursor.
8
dioxane
t-AmylOH
42
This ligand was prepared from the TMS-protected (2R,5R)-2,5-
dimethylphospholane by a modified literature procedure.[ 16 ]
Elemental analysis as well as three carbonyl bands in the IR
9[c]
35
1
0
t-AmylOH
t-AmylOH
heptane
30
40
30
74
90/10
92/08
90/10
-1
spectrum (2009, 1908, 1821 cm ) pointed out that a ionic
complex is formed which is also confirmed by X-ray
crystallography. As shown in figure the manganese is
11
>99
>99
6
12
2
coordinated by the pincer and three carbonyl ligands in a
distorted octahedral geometry.
[
5
a] 7a (0.5 mmol), 6 (0.005 mmol), solvent (1 mL), NaOtBu (5 mol%), 3 h, 30-
0 °C, 30 bar H . In all cases the R enantiomer is favoured. [b] Yield
2
determined by GC analysis using hexadecane as an internal standard. [c]
Used as purchased - not dried.
To establish the general applicability of the chiral
manganese pincer catalyst 6, the hydrogenation of different
aliphatic ketones was studied (1 mol% 6, 5 mol% KOtBu, 30 bar
2
H , 40 °C, 4 h, tert-amyl alcohol). As shown in Figure 3, for the
smallest cyclic aliphatic substrate cyclopropyl methyl ketone (7b)
the er decreased to 85:15, while cyclopentyl methyl ketone (7c)
gave 87:13 er at high conversion. In case of cyclohexyl ethyl
ketone a lower activity and selectivity was observed (7d).
Figure 2. Molecular structure of the cation of complex 6 (for more details see
SI). Displacement ellipsoids corresponds to 30% probability. Lower occupancy
sites and hydrogen atoms except that attached to nitrogen are omitted for
clarity. Selected bond lengths [Ǻ] and angles [°]: Mn1-P1 2.2629(17), Mn1-P2
2.2741(17), Mn1-N1 2.109(3), P1-Mn1-P2 166.43(5), P1-Mn1-N1 83.06(12),
P2-Mn1-N1 83.38(13).
Having a well-defined chiral manganese pre-catalyst 6 in
hand, we tested the hydrogenation of cyclohexyl methyl ketone
7a) as a model substrate for the reduction of aliphatic ketones.
Initial tests applying 1 mol% 6 revealed moderate conversion at
0 bar of hydrogen and 50 °C. Interestingly, in most cases the
choice of solvent had only small influence on the
(
3
a
enantioselectivity, while the effect on the catalyst activity is more
pronounced (Table 1).
Figure 3. Manganese-catalyzed hydrogenation of aliphatic ketones. General
conditions: Substrate (1 mmol), 6 (1 mol%), KOtBu (5 mol%), tert-amyl alcohol
To our delight, high enantiomeric ratios (90:10 and 89:11,
respectively) and complete conversion were obtained in heptane
and tert-amyl alcohol after only 3h favoring the R enantiomer
2
(2 mL), 4 h, 40 °C, 30 bar H . Conversion was determined by GC using
hexadecane as internal standard. [a] 4 h, 80 °C. [b] 6 (2 mol%), toluene (2 mL),
4 h, 50 °C. 6 % cyclohexanol. [c] 6 (2 mol%), tert-amyl alcohol (2 mL), 4 h,
(
Table 1, entries 2 and 5).[17] A slightly higher selectivity (92:8 er)
8
0 °C.
is observed in i-PrOH (Table 1, entry 7). From a practical point
of view it is noteworthy that the catalyst is also active in non-
dried solvents (Table 1, entries 5 and 9). Using optimal
conditions, it was possible to run the model reaction at (30-
On the other hand, 4-acetyltetrahydropyran showed high
conversion and gave good er 90:10. Similarly, different cyclic
ketones with a conjugated double bond were smoothly reduced
40 °C) reaching 92:8 er and quantitative yield (Table 1, entries
(
Figure 3, 7f-h). Notably, catalyst 6 is highly stereo- and
10-12; see SI for further optimizations).
chemoselective. Within this substrate class, 2-cyclohexen-1-one
gave the highest er value of 81:19. In addition acyclic aliphatic
ketones were tested using 2 mol% catalyst loading at 80 °C.
Both substrates (9i and 9j) gave full conversion; however 3-
methyl-2-butanone showed good selectivity (er 84:16), while for
Table 1. Mn-catalyzed hydrogenation of cyclohexyl methyl ketone 7a:
Optimization of the reaction conditions[a]
4
-methyl-2-pentanone a lower enantiomeric ratio (65:35) was
observed.
Next to aliphatic ketones, we tested the hydrogenation of
aromatic ketones. Surprisingly, the parent compound
acetophenone (Figure 4, 9a) gave only low enantioselectivity (er
Entry
Solvent
T
Yield[b] [%]
er (%)
5
3
9:41) even under mild conditions (0.5 mol% 6, 30 bar, 30 °C,
h). Similar results were observed for substituted acetophenone
1
2
CH
2
Cl
2
50
50
29
88/12
90/10
heptane
>99
This article is protected by copyright. All rights reserved.

Angewandte Chemie International Edition
10.1002/anie.201705471
COMMUNICATION
derivatives like butyrophenone or 4-methoxyacetophenone (9c-
d). In contrast, the catalyst showed an increased selectivity for
heteroaromatic substrates (9d-f) like 2-acetylthiophene or 2-
furylmethylketone (85:15 er). To our delight α-tetralone and α-
indanone (9g-h) as acetophenone analogues were also reduced
to the corresponding alcohols with er values up to 90:10
whereas the reaction of α-tetralone needs slightly elevated
temperature (60°C) for complete conversion.
enantioface (Scheme 3); and the different steric repulsion
between the ketone substituents and methyl groups of the chiral
phosphorus ligand in R and S configurations should be the origin
of asymmetric induction. The energy difference between the
transition states of the R and S configurations determines the
enantiomeric ratio. Compared with the stepwise mechanism of
benzaldehyde hydrogenation by non-chiral Mn PNP complexes
with isopropyl groups on the phosphorous centre,[
11c]
a
concerted and strongly asynchronous transition state was
located for all substrates, and this is further confirmed by the
intrinsic reaction coordinate (IRC) calculations.
For cyclohexyl methyl ketone hydrogenation we found an
enantiomeric ratio of 97/3 for (R)-1-cyclohexylethan-1-ol (Gibbs
free energy barrier of 31.4/33.5 kcal/mol for the R/S transition
states). For cyclopentyl methyl ketone hydrogenation, the
computed enantiomeric ratio is 97/3 for (R)-1-cyclopentylethan-
1-ol (Gibbs free energy barrier of 31.4/33.5 kcal/mol for the R/S
transition states). For α-tetralone hydrogenation, we found an
enantiomeric ratio of 97/3 for (S)-α-tetralol (Gibbs free energy
barrier of 33.5/35.6 kcal/mol for the S/R transition states).
Although the computed enantiomeric ratios are higher than the
experimentally determined data (89/11, 87/13 and 10/90,
respectively), the experimentally observed sense of induction is
qualitatively reproduced.
To understand the origin of these energy differences, we
dissected the energy of the R/S transition states. As explained in
the Supporting Information (Table SI 5), the strain energy
difference of the catalyst between the R/S transition states
dominates the energy difference for the hydrogenation of
cyclohexyl methyl ketone and cyclopentyl methyl ketone. For the
hydrogenation of α-tetralone, the strain energy differences of
both catalyst and substrate between the R/S transition states
contribute to the strain energy. Further analysis into the root-
mean-square deviations of atomic position of the catalyst in R/S
transition states reveals that the C16 methyl group undergoes
stronger deformation than the C10 methyl group for the
hydrogenation of cyclohexyl methyl ketone and cyclopentyl
methyl ketone, while just opposite phenomena have been found
for the hydrogenation of α-tetralone (Figure SI 31).
Figure 4. Manganese-catalysed asymmetric hydrogenation of aromatic
ketones. General conditions: substrate (1 mmol), 6 (1 mol%), KOtBu (5 mol%),
2
1,4-dioxane (2 mL), 4 h, 30 °C, 30 bar H . Conversion was determined by GC
using hexadecane as internal standard (Isolated yield in parenthesis).
On the basis of the above discussed experimental results,
gas-phase B3PW91 DFT computations were carried out to
elucidate the enantioselective hydrogenation mechanism. The
computational details are given in Supporting Information. On
the basis of our previous work[11c,e] we propose an outer-sphere
mechanism with the neutral PNP amine complex A and the
corresponding amido complex
(
B
as the active catalysts
Scheme 3) involved.[ The potential energy surfaces are given
11j
in Supporting Information. The computed and X-ray determined
structural parameters of the cation complex 6 are in excellent
agreement (Table S1).
Our computations show that the hydride complex A is very
stable towards CO dissociation (> 42 kcal/mol). The concerted
H
2
2
elimination from A to B has Gibbs free energy barrier of
0.3 kcal/mol and is slightly endergonic (0.8 kcal/mol), indicating
a facile reversibility and well-balanced equilibrium between A
2
and B under H atmosphere, close with those of ethyl, isopropyl
and cyclohexyl substituted PNP Mn complexes.[11e]
For cyclohexyl methyl ketone full conversion was observed
(
(
>99 %), while a lower conversion for cyclopentyl methyl ketone
61 %) and for α-tetralone (70 %) was found under 30 bar H
2
pressure. This can be explained by the computed reaction free
energies energy, i.e.; roughly thermal neutral for cyclohexyl
methyl ketone (-1.0 kcal/mol), and endergonic for the aromatic
one (2.9 kcal/mol). The endergonic property for α-tetralone
hydrogenation indicates that the dehydrogenation reaction is
more favoured both kinetically and thermodynamically than the
hydrogenation reaction. One can expect that ketone rather than
alcohol is more favoured under stoichiometric condition. Thus,
high H
In addition, the computed barriers of ketone hydrogenation
(30-36 kcal/mol) are much higher than the barrier of H
elimination from amine complex to amido complex
20.3 kcal/mol); indicating that high H pressure is necessary to
maintain the stability of the active catalyst A, in line with the
experimental condition (30 bar H ).
2
pressure is needed to shift the equilibrium to alcohol.
Scheme 3. Proposed mechanism for ketone hydrogenation (PR *
phosphlane ligand in R configuration)
for chiral
2
2
A
B
Next we used cyclohexyl methyl ketone, cyclopentyl methyl
ketone and α-tetralone to test the enantioselectivity. On the
basis of these prostereogenic ketones, the asymmetric induction
derives from the approach of the ketone group perpendicular to
the N-H and Mn-H groups in cis position either with the re or si
(
2
2
In conclusion we described a new type of chiral manganese
pincer complex and showed its applicability for the reduction of
This article is protected by copyright. All rights reserved.

Angewandte Chemie International Edition
10.1002/anie.201705471
COMMUNICATION
various ketones. In comparison to the manganese pincer
catalyst which was recently developed by Clarke for the
asymmetric hydrogenation of aromatic ketones, our reported
system preferentially reduces aliphatic ketones with high
enantioselectivities. The mechanistic studies confirmed an outer
sphere mechanism whereas the calculated stereochemistry is in
line with the experimental data.
Sonnenberg, A. J. Lough, R. H. Morris, Organometallics 2014, 33,
6452-6465; c) A. Zirakzadeh, K. Kirchner, A. Roller, B. Stöger, M.
Widhalm, R. H. Morris, Organometallics 2016, 35, 3781-3787; d) J. F.
Sonnenberg, K. Y. Wan, P. E. Sues, R. H. Morris, ACS Catal. 2017, 7,
316-326; e) S. A. M. Smith, P. O. Lagaditis, A. Lüpke, A. J. Lough, R. H.
Morris, Chem. Eur. J. 2017, DOI: 10.1002/chem.201701254.
[
10] a) Y. Y. Li, S. L. Yu, W. Y. Shen, J. X. Gao, Acc. Chem. Res. 2015, 48,
2587-2598; b) P. O. Lagaditis, P. E. Sues, A. J. Lough, R. H. Morris,
Dalton Trans. 2015, 44, 12119-12127; c) W. Zuo, D. E. Prokopchuk, A.
J. Lough, R. H. Morris, ACS Catal. 2016, 6, 301-314; d) R. Bigler, R.
Huber, M. Stöckli, A. Mezzetti, ACS Catal. 2016, 6, 6455-6464.
Acknowledgements
[
11] a) For a recent review on manganese pincer complexes see: M. Garbe,
K. Junge, M. Beller, Eur. J. Org. Chem. 2017 DOI:
We thank Dr. C. Fischer, S. Buchholz, S. Schareina (all LIKAT)
for their excellent analytical support. We thank Prof. Dr. A.
Börner and Dr. J. Holz for a gift of (R,R)-2,5-dimethyl-1-
10.1002/ejoc.201700376; b) A. Mukherjee, A. Nerush, G. Leitus, L. J.
Shimon, Y. Ben David, N. A. Espinosa Jalapa, D. Milstein, J. Am. Chem.
Soc. 2016, 138, 4298-4301; c) S. Elangovan, C. Topf, S. Fischer, H.
Jiao, A. Spannenberg, W. Baumann, R. Ludwig, K. Junge, M. Beller, J.
Am. Chem. Soc. 2016, 138, 8809-8814; d) F. Kallmeier, T. Irrgang, Th.
Dietel, R. Kempe, Angew. Chem. Int. Ed. 2016, 55, 11806-11809;
Angew. Chem. 2016, 128, 11984-11988; e) S. Elangovan, M. Garbe, H.
Jiao, A. Spannenberg, K. Junge, M. Beller, Angew. Chem. Int. Ed. 2016,
(
(
trimethylsilyl)phospholane as well as Leibniz Association
Leibniz Competition, SAW-2016-LIKAT-1) for financial support.
Keywords: manganese
•
chiral pincer
•
asymmetric
hydrogenation • ketones • chiral alcohols
5
5, 15364-15368; Angew. Chem. 2016, 128, 15590-15594; f) M. Perez,
S. Elangovan, A. Spannenberg, K. Junge, M. Beller, ChemSusChem
016, 10, 83-86; g) M. Mastalir, M. Glatz, E. Pittenauer, G. Allmaier, K.
2
[
1]
2]
R. Noyori, Angew. Chem. Int. Ed. 2002, 41, 2008-2022; Angew. Chem.
002, 114, 2108-2123.
"The Nobel Prize in Chemistry 2001". Nobelprize.org. Nobel Media AB
014.
Kirchner, J. Am. Chem. Soc. 2016, 138, 15543-15546; h) M. Mastalir,
M. Glatz, N. Gorgas, B. Stoger, E. Pittenauer, G. Allmaier, L. F. Veiros,
K. Kirchner, Chemistry 2016, 22, 12316-12320; i) N. A. Espinosa-
Jalapa, A. Nerush, L. J. W. Shimon, G. Leitus, L. Avram, Y. Ben-David,
D. Milstein, Chem. Eur. J. 2017, 23, 5934-5938; j) D. C. Nguyen, X.
Trivelli, F. Capet, J.-F. Paul, F. Dumeignil, R. M. Gauvin, ACS Catal.
2017, 7, 2022-2032; k) V. Papa, J. R. Cabrero-Antonio, E. Alberico, A.
Spannenberg, K. Junge, H. Junge, M. Beller, Chem. Sci. 2017, 8, 3576-
3585.
2
[
2
[
3]
4]
W. S. Knowles, M. J. Sabacky, Chem. Comm. 1968, 1445-1446.
[
L. Horner, H. Siegel, H. Büthe, Angew. Chem. Int. Ed. 1968, 7, 942-
942; Angew. Chem. 1968, 80, 1034-1035.
[5]
a) T. P. Dang, H. B. Kagan, J. Chem. Soc. D 1971, 481-481. b) W. S.
Knwoles, M. J. Sabacky, B. D. Vineyard, D. J. Weinkauff, J. Am. Chem.
Soc. 1975, 97, 2567-2568. c) W. S. Knowles, Angew. Chem. Int. Ed.
[12] A. Zirakzadeh, S. R. M. M. de Aguiar, B. Stöger, M. Widhalm, K.
Kirchner, ChemCatChem 2017, DOI: 10.1002/cctc.201700042.
[13] M. B. Widegren, G. J. Harkness, A. M. Z. Slawin, D. B. Cordes, M. L.
Clarke, Angew. Chem. Int. Ed. 2017, 5825-5828; Angew. Chem. 2017,
129, 5919-5922.
2002, 41, 1998-2007; Angew. Chem. 2002, 114, 2096–2107. d) A.
Miyashita, A. Yasuda, H. Takaya, K. Toriumi, T. Ito, T. Souchi, R.
Noyori, J. Am. Chem. Soc. 1980, 102, 7932-7934.
[
6]
7]
a) K. Mashima, T. Ohshima, H. Shimizu, T. Nagano, N. Sayo, T. Saito,
Synlett 2009, 2009, 3143-3146. b) H. Shimizu, D. Igarashi, W.
Kuriyama, Y. Yusa, N. Sayo, T. Saito, Org. Lett. 2007, 9, 1655-1657.
a) C. P. Casey, H. Guan, J. Am. Chem. Soc. 2007, 129, 5816-5817. b)
C. Sui-Seng, F. Freutel, A. J. Lough, R. H. Morris, Angew. Chem. Int.
Ed. 2008, 47, 940-943; Angew. Chem. 2008, 120, 954-957. c) S.
Enthaler, K. Junge, M. Beller, Angew. Chem. Int. Ed. 2008, 47, 3317-
[14] a) A. Zanotti-Gerosa, W. Hems, M. Groarke, F. Hancock, Platinum Met.
Rev. 2005, 49, 158-165; b) M. Yoshimura, S. Tanaka, M. Kitamura,
Tetrahedron Lett. 2014, 55, 3635-3640; c) A. Schlatter, M. K. Kundu, W.
D. Woggon, Angew. Chem. Int. Ed. 2004, 43, 6731-6734; Angew.
Chem. 2014, 116, 6899-6902; d) J. G. de Vries, C. J. Elsevier, The
Handbook of Homogeneous Hydrogenation, VCH, Weinheim, 2008, p.
1147 ff.
[
3321; Angew. Chem. 2008, 120, 3363-3367. d) R. H. Morris, Chem.
Soc. Rev. 2009, 38, 2282-2291. e) J. P. Hopewell, J. E. Martins, T. C.
Johnson, J. Godfrey, M. Wills, Org. Biomol. Chem. 2012, 10, 134-145.
f) M. Darwish, M. Wills, Catal. Sci. Technol. 2012, 2, 243-255. g) A.
Berkessel, S. Reichau, A. von der Hꢀh, N. Leconte, J. r.-M. Neudꢀrfl,
Organometallics 2011, 30, 3880-3887. h) Y. Li, S. Yu, X. Wu, J. Xiao,
W. Shen, Z. Dong, J. Gao, J. Am. Chem. Soc. 2014, 136, 4031-4039.
a) For an overview about reduction of ketones by iron complexes see:
R. H. Morris, Chem. Soc. Rev. 2009, 38, 2282-2291; b) C. Sui-Seng, F.
Freutel, A. J. Lough, R. H. Morris, Angew. Chem. Int. Ed. 2008, 47,
[15] a) A. M. Tondreau, J. M. Boncella, Organometallics 2016, 35, 2049-
2052; b) A. M. Tondreau, J. M. Boncella, Polyhedron 2016, 116, 96-
104; c) A. Nerush, M. Vogt, U. Gellrich, G. Leitus, Y. Ben-David, D.
Milstein, J. Am. Chem. Soc. 2016, 138, 6985-6997; d) S. Elangovan, J.
Neumann, J. B. Sortais, K. Junge, C. Darcel, M. Beller, Nature
communications 2016, 7, 12641-12648; e) M. Pena-Lopez, P. Piehl, S.
Elangovan, H. Neumann, M. Beller, Angew. Chem. Int. Ed. 2016, 55,
14967-14971; Angew. Chem. 2016, 128, 15191-15195; f) R. van Putten,
E. A. Uslamin, M. Garbe, C. Liu, A. Gonzalez-de-Castro, M. Lutz, K.
Junge, E. J. M. Hensen, M. Beller, L. Lefort, E. A. Pidko, Angew. Chem.
Int. Ed. 2017, 56, 7531-7534.
[8]
940-943; Angew. Chem. 2008, 120, 954-957; c) N. Meyer, A. J. Lough,
R. H. Morris, Chem. Eur. J. 2009, 15, 5605-5610; d) A. Mikhailine, A. J.
Lough, R. H. Morris, J. Am. Chem. Soc. 2009, 131, 1394-1395; e) P. E.
Sues, A. J. Lough, R. H. Morris, Organometallics 2011, 30, 4418-4431;
f) W. Zuo, S. Tauer, D. E. Prokopchuk, R. H. Morris, Organometallics
[16] a) M. J. Burk, J. E. Feaster, R. L. Harlow, Tetrahedron: Asymmetry
1991, 2, 569–592; b) M. J. Burk (Du Pont), WO 92/19630, 1992; c) K.
Abdur-Rashid, US 20050107638, 2005.
2
014, 33, 5791-5801.
[17] The absolute stereochemistry of 10c was determined by comparison
with the authentic S-enantiomer.
[9]
a) P. O. Lagaditis, P. E. Sues, J. F. Sonnenberg, K. Y. Wan, A. J.
Lough, R. H. Morris, J. Am. Chem. Soc. 2014, 136, 1367-1380; b) J. F.
This article is protected by copyright. All rights reserved.

Angewandte Chemie International Edition
10.1002/anie.201705471
COMMUNICATION
Entry for the Table of Contents
COMMUNICATION
Marcel Garbe, Kathrin Junge, Svenja
Walker, Zhihong Wei, Haijun Jiao, Anke
Spannenberg, Stephan Bachmann,
Michelangelo Scalone and Matthias
Beller*
Page No. – Page No.
A new type of chiral manganese pincer complex has been developed and its
applicability for the reduction of aromatic and aliphatic ketones is demonstrated.
Manganese(I)-catalyzed
Enantioselective Hydrogenation of
Ketones using a Defined Chiral PNP
Pincer Ligand
This article is protected by copyright. All rights reserved.