Experimental and Computational Study of an Unexpected Iron-Catalyzed Carboetherification by Cooperative Metal and Ligand Substrate Interaction and Proton Shuttling

Article abstract of DOI:10.1002/anie.201708240

An iron-catalyzed cycloisomerization of allenols to deoxygenated pyranose glycals has been developed. Combined experimental and computational studies show that the iron complex exhibits a dual catalytic role in that the non-innocent cyclopentadienone ligand acts as proton shuttle by initial hydrogen abstraction from the alcohol and by facilitating protonation and deprotonation events in the isomerization and demetalation steps. Molecular orbital analysis provides insight into the unexpected and selective formation of the 3,4-dihydro-2H-pyran.

Full text of DOI:10.1002/anie.201708240

A Journal of the Gesellschaft Deutscher Chemiker
Angewandte
Chemie
International Edition
www.angewandte.org
Accepted Article
Title: Experimental and computational study of an unexpected iron
catalyzed carboetherfication by cooperative metal and ligand
substrate interaction and proton shuttle
Authors: Magnus Rueping
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.201708240
Angew. Chem. 10.1002/ange.201708240
Link to VoR: http://dx.doi.org/10.1002/anie.201708240
http://dx.doi.org/10.1002/ange.201708240

10.1002/anie.201708240
Angewandte Chemie International Edition
COMMUNICATION
Experimental and computational study of an unexpected iron
catalyzed carboetherfication by cooperative metal and ligand
substrate interaction and proton shuttle
Osama El-Sepelgy,*[a] Aleksandra Brzozowska,[a] Luis Miguel Azofra,[b] Yoon Kyung Jang,[a] Luigi
Cavallo,[b] and Magnus Rueping[a,b]
Dedicated to Prof. Dr. Dieter Seebach on the occasion of his 80th birthday
Abstract: A new iron catalyzed cycloisomerization of allenols to
deoxygenated pyranose glycals has been developed. Combined
experimental and computational studies show that the iron complex
exhibits
a
dual catalysis role in that the non-innocent
cyclopentadienone ligand acts as proton shuttle by initial hydrogen
abstraction of the alcohol and by facilitating protonation and
deprotonation events in the isomerization and demetalation steps.
Molecular orbital analysis provides insight into the unexpected and
selective formation of the 3,4-dihydro-2H-pyrane.
The development of new atom-economical transformations is
one of the most important challenges in modern synthetic
chemistry.[1] Key for the sustainable future of industrial chemistry
is the replacement of precious metal catalysts by the first-row,
earth-abundant catalysts.[2] In this regard the use of iron salts
and complexes has become an important field.[3] More recently
iron tricarbonyl complexes have attracted considerable interest
due to their redox activity, robust nature and ready accessibility.
However, so far the application of the iron tricarbonyl complexes
is mainly restricted to the reduction of polar bonds and hydrogen
borrowing transformations.[4-6]
During our recent investigations on the use of iron tricarbonyl
complexes as Fe-hydrogenase mimics we observed an
unexpected carboetherification of allenic alcohols (Scheme 1).[7]
Herein, we report our preliminary results on the experimental
and computational exploration of this first iron tricarbonyl
catalyzed carboetherfication of the allenic alcohols which gives
access to valuable 3,4-dihydro-2H-pyrans, a heterocycle which
is ubiquitous in natural products and is frequently used as a
precursor of the synthesis of bioactive molecules, including
glycals, polyethers and deoxynucleocides antibiotics.[8]
Previously the cyclization of β-hydroxyallenes using gold(I)
catalysts has been established. However, these reactions afford
Scheme 1. Iron catalyzed carboetherfication of allenols.
In preliminary experiments, the carboetherfication of the allenol
10a was investigated using the iron complexes Fe1-Fe9 (Figure
1) in toluene at 70 °C. The air and moisture stable pre-catalysts
were activated in situ by oxidative decarbonylation using
trimethylamine N-oxide. Application of Fe1 gave only 17% yield
of the desired enol ether 11a, while Fe2 afforded the same
product in 25% yield (Table 1, entries 1-2). The iron complexes
Fe3, Fe4 or Fe5[11] did not show any catalytic activity (Table 1,
entries 3-5). A slightly better result was obtained when Fe6 was
used (Table 1, entry 6). In hydrogen transfer processes the iron
hydride is the reactive iron species and the hydrogen transfer
occurs via an outer sphere pathway. Therefore, a bulky
substituent on the dienone ligand is crucial for the complex
stability and catalytic activity. However, in the carbocyclization
under investigation the iron complex bearing a non-innocent
ligand may exhibit a dual role.[12] Activation of the allene may
occur via
a metal π-interaction while simultaneously the
nucleophile is activated by a hydrogen bond abstraction through
the dienone moiety of the ligand. Thus, the use of an iron
catalyst, which is bearing smaller substituents should lead to
improved results. To our delight, full conversion and good yield
(84%) was observed if Fe7 was employed (Table 1, entry 7). In
order to investigate the effect of the electron density on the
cyclopentadienone moiety, the electron rich iron complex Fe8
and the comparably more electron deficient catalyst Fe9 were
tested. However, no change in yield was observed indicating
that the electron density does not change the catalyst activity
(Table 1, entries 8-9). The addition of catalytic amounts of DBU
had a detrimental effect on the reactivity and only 35% yield was
obtained (Table 1, entry 10). Importantly, increasing the reaction
concentration did not influence the yield (Table 1, entry 11).
Finally, when the iron trichloride was used as a catalyst no
product formation was observed (Table 1, entry 12).
the
regioisomer
3,6-dihydro-2H-pyrane,
indicating
a
mechanistically distinct pathway.[9,10]
[a]
[b]
Dr. O. El-Sepelgy, A. Brzozowska, Y. K. Jang, Prof. Dr. M. Rueping
Institute of Organic Chemistry
RWTH Aachen University
Landoltweg 1, 52074 Aachen (Germany)
E-mail: elsepelgy@oc.rwth-aachen.de
E-mail: magnus.rueping@rwth-aachen.de
Dr. L. M. Azofra, Prof. Dr. L. Cavallo, Prof. Dr. M. Rueping
KAUST Catalysis Center (KCC)
King Abdullah University of Science and Technology (KAUST)
Thuwal 23955-6900 (Saudi Arabia)
E-mail: luigi.cavallo@kaust.edu.sa
Supporting information for this article is given via a link at the end of
the document.
This article is protected by copyright. All rights reserved.

10.1002/anie.201708240
Angewandte Chemie International Edition
COMMUNICATION
To demonstrate the potential and applicability of this
methodology, an array of allenic alcohols was cyclized (Table 2).
In general, aryl substituted allenols with both electron donating
as well as electron withdrawing groups could be successfully
applied and the corresponding pyrans (11b-h) were isolated in
good yields (entries 2-8).
Table 2. Iron-catalyzed 6-endo hetrocyclization of β-allenols.[a]
Entry
Product
Entry
Product
Figure 1. Selection of iron cyclopentadienone complexes applied in the
carbocyclization.[4]
Table 1. Optimization of the reaction conditions.[a]
Additive
(mol%)
Yield
Entry
Cat. (mol%)
(%)[b]
1
2
Fe1 (5)
Fe2 (5)
Fe3 (5)
Fe4 (5)
Fe5 (5)
Fe6 (5)
Fe7 (5)
Fe8 (5)
Fe9 (5)
Fe7 (5)
Fe7 (5)
FeCl3 (10)
Me3NO (5.5)
Me3NO (5.5)
Me3NO (5.5)
Me3NO (5.5)
Me3NO (5.5)
Me3NO (5.5)
Me3NO (5.5)
Me3NO (5.5)
Me3NO (5.5)
Me3NO (5.5) / DBU (20)
Me3NO (5.5)
-
17
25
0
3
4
0
5
0
6
38
85
85
85
35
85
0
7
8
9
10
11[c]
12
[a] The reactions were performed on 0.2 mmol scale with an iron complex and
additive in 1 mL of toluene-d8 at 70 °C in a Schlenk tube under an inert
atmosphere for 16h. [b] Yields were determined by the H1 NMR analysis of the
crude reaction mixture using 1,3.5-trimethoxybenzene as an internal standard.
[c] The reaction was performed in 1 mmol scale in 1 mL of toluene.
We then decided to investigate the carboetherification of the
enantiomercally pure (R)-10a under the optimized reaction
conditions. Pleasingly, the reaction proceeded with complete
retention of configuration and provided the optically pure enol
ether (R)-11a in 81% yield and 99% ee (Scheme 2). This result
indicates that the cyclization reaction is much faster than the
alcohol racemization pathway previously established.[5]
[a] Reaction conditions: 10 (1 mmol) and catalyst Fe7 (5 mol%) and Me3NO
(5.5 mol%) in toluene (1 mL) were stirred at 70 °C for 16h in a Schlenk tube
under an inert atmosphere. Yields after column chromatography.
Furthermore, the cyclic and acyclic aliphatic derivatives 10i and
10j were cycloisomerized to the unsaturated pyrans 11i and 11j
in 74% and 82% yields respectively (entries 9-10). Importantly,
the pyrane 11k was produced in good yield (entry 11). This
deoxy sugar is of relevance as it can be used in the synthesis of
the six membered analogues of several clinically relevant
antibiotics such as AZT, d4T and Puromycin.[13] The method was
Scheme 2. Retention of chirality in the intramolecular carboetherification.
This article is protected by copyright. All rights reserved.

10.1002/anie.201708240
Angewandte Chemie International Edition
COMMUNICATION
also found to be applicable to heteroarenes as shown by
derivative 10l (entry 12). Moreover, the carboetherfication of the
tertiary alcohol 10m gave the pyrane 11m with a quaternary
carbon atom (entry 13). Finally, product 11n was obtained in
67% yield demonstrating a new and efficient method for the
construction of spirocyclic ethers (entry 14). Following the
successful demonstration of the variability and applicability of
the newly developed iron catalyzed carboetherification we
decided to examine the cyclization of the more challenging
aromatic allenol 12. To our delight, the iron complex catalyzed
the regioselective 7-endo heterocyclization and afforded the
interesting 2-benzoxepine 13 (Scheme 3).[14]
terminal double bond of the allene and at the time forms a H-
bond between the alcohol moiety of the allene and the C=O
group of the cyclopentadienone (intermediate B; see additional
details in the Supporting Information). Hence, the ligand plays a
crucial role in the activation of the substrate and as such
belongs to the group of cooperative or non-innocent type
ligands.[12] The activated O atom of B can undergo a 6-endo-dig
attack with transfer of the alcoholic
H
atom to the
cyclopentadienone ligand, leading to the formation of the iron
vinylidene intermediate C, via transition state (TS B C, Figure
3) and a Gibbs free energy barrier (ΔGact) of 18.6 kcal mol–1 at
70 °C. The next step along the preferred reaction pathway is the
isomerization of the iron vinylidene intermediate C into the more
stable (by 2.6 kcal mol-1) iron vinylidene intermediate E via the
iron carbene intermediate D, see Figure 2 and 3. This
isomerization consists of two consecutive H-transfers. The first is
from the cyclopentadienone ligand to the C4 atom of the
substrate, the second from the C6 atom of the substrate to the
cyclopentadienone ligand, with the low ΔGact of 14.2 (C  D)
and 3.2 (D’  E) kcal mol–1. The observed deuterium distribution
confirms the equilibrium between intermediates C and D. The
catalytic cycle is completed by protodemetalation of the iron
Scheme 3. Iron catalyzed 7-endo heterocyclization.
In order to gain more insight into the nature of the catalytic
active iron species, we conducted a series of deuterium labeling
experiments using the iron catalyst Fe7 (Scheme 4). When the
heterocyclization reaction was performed with allenic alcohol
10a-d1, the unsaturated pyrane 11a-d1 was formed with 14%
deuterium incorporation at vinylic position C5 and 44% and 29%
in the allylic hydrogen atoms on C4. In the case of allenol 10a-d2,
complete deuterium incorporation was detected at C6 position
and deuterium incorporation was detected on both C4 and C5.
The carboetherification of 10a-d3 afforded the cyclic product with
complete deuterium incorporation at C6 position and double
deuterium incorporation was found on both C4 and C5.
vinylidene intermediate
E
to the product coordinated
intermediate F (ΔGact = 15.0 kcal mol–1). Product dissociation
costs 11.3 kcal mol-1 and regenerates the activated catalyst A.
Figure 2. Proposed catalytic cycle.
Scheme 4. Deuterium labelled experiment.
Consistently with experiments, the competitive formation of the
3,6-dihydro-2H-pyran, P2, via protodemetalation of intermediate
C (ΔGact = 26.8 kcal mol–1) is disfavored over protodemetalation
of intermediate E which gives the 3,4-dihydro-2H-pyran, P1
With this experimental background in mind we performed DFT
calculations to rationalize the possible reaction mechanism
(Figure 2,3) as well as the selective 3,4-dihydro-2H-pyran
formation. As shown in Figure 2 and 3, the catalytically active
species A is initially produced by the partial decarbonylation of
the iron tricarbonyl pre-catalyst Fe7. This 16e iron species
exhibits a dual catalysis behavior as it can coordinate to the
(ΔGact
=
15.0 kcal mol–1). The different propensity of
and to undergo protodemetalation is
intermediates
C
E
rationalized by comparison of the electronic properties of the C5
carbon of C and E.
This article is protected by copyright. All rights reserved.

10.1002/anie.201708240
Angewandte Chemie International Edition
COMMUNICATION
Initialization: Fe7 + Me3NO ® A + CO2 + Me3N, DGR = –55.9 kcal mol–1
Fe7
+
OH
TS(C®P2)
TS(B®C)
7.1
6.5
A + allenol
26.8
0.0
TS(D’®E)
–5.9
TS(C®D)
–5.6
TS(E®F)
–7.9
18.6
O
D
–10.1
14.2
D’
–9.1
3.2
enol ether
15.0
B
E
–12.1
–22.9
A + P1
–25.5
C
–19.7
A + P2
–20.3
O
F
–36.8
Reaction coordinate
Figure 3. Proposed reaction mechanism. Gibbs free energies (70 °C), in kcal mol–1. Results at the M06/TZVP level including solvent effects (toluene) through the
PCM approach.[15-16] Reactive H atoms are highlighted in blue and green colors. D and D’ structures are conformational minima. For clarity, phenyl groups from
the cyclopentadienone moiety have been omitted. (See full computational details and full structures in the Supporting Information).
The former has a higher natural population charge, qNBO, and
Fukui nucleophilicity index (f–), consistent with the higher
reactivity (lower ΔGact) of E (see Figure 4). Molecular orbital
(MO) analysis of C and E (Figure 4) indicates that the saturated
C6 of C prevents mixing of the O p-orbital with the -orbital of
the C4=C5 double bond. Conversely, the p-orbital on the O-atom
can mix with the -orbital of the C5=C6 double bond in E,
In conclusion, we here report
a
new iron catalyzed
carboetherfication of allenols. The reaction represents not only
the first example in which an iron cyclopentadienone complex is
used for carbon-heteroatom formation but, more importantly,
readily available allenic alcohols can be easily transformed into
deoxygenated pyranose glycals which are important building
blocks for the synthesis of bioactive molecules and natural
products. Mild reaction conditions, good functional group
tolerance as well low catalyst loadings of an air stable
inexpensive iron complex are characteristics of this new
resulting in
a bonding interaction (explaining the higher
thermodynamic stability of P1 relative to P2), and in an anti-
bonding interaction that reduces the energy gap with the empty
MO corresponding to the –OH bond from 3.58 to 2.94 eV,
explaining the higher reactivity of E.
transformation. Computational studies support
a reaction
mechanism in which the iron cyclopentadienone complex plays
a dual role. While the catalytically active 16e iron species is
coordinating to the allene, the non-innocent cyclopentadienone
ligand acts as proton shuttle by initial hydrogen abstraction of
the alcohol and by facilitating protonation and deprotonation
events in the isomerization and demetalation steps. Furthermore,
the unexpected formation of the 3,4-dihydro-2H-pyrane as
compared to the previously observed 3,6-dihydro-2H-pyrane can
be explained through molecular orbital analysis of the iron
vinylidene intermediate which demonstrates that formation of the
enol product is more favorable. Thus, the results of this
combined computational and experimental study will guide
explorations in the design of further new reactions using iron
cyclopentadienone tricarbonyl complexes in metal-ligand
cooperative catalysis.
O
O
a)
b)
[Fe]
[Fe]
qNBO = –0.122 au
f – = 0.014 au
qNBO = –0.232 au
f – = 0.083 au
C
E
O
O
–1.49
–1.63
H
H
2.94
3.58
O
O
↑↓
↑↓
O
[Fe]
↑↓
↑↓
–4.57
[Fe]
[Fe]
–5.07
–5.26
[Fe]
O
–8.38
Figure 4. a) Natural population charge, qNBO, and nucleophilic Fukui function,
f–; and b) MO analysis for the C and E iron vinylidene intermediates.
This article is protected by copyright. All rights reserved.

10.1002/anie.201708240
Angewandte Chemie International Edition
COMMUNICATION
Widenhoefer, Chem. Eur. J. 2008, 14, 5382; d) S. Ma, Acc. Chem Res.
2009, 42, 1679; e) N. Krause, C. Winter, Chem. Rev. 2011, 111, 1994.
[11] The X-ray crystal structure of the complex Fe5 suggested that the
phenyl rings are almost perpendicular. This rotation is properly due to
the N-Me substituents (for details, see ref 4f).
Acknowledgements
L.M.A. and L.C. acknowledge King Abdullah University of
Science and Technology (KAUST) for support. Gratitude is also
due to the KAUST Supercomputing Laboratory using the
supercomputer Shaheen II for providing the computational
resources.
[12] Selected reviews on non-innocent or cooperative ligands, see: a) R.
Khusnutdinova, D. Milstein, Angew. Chem. Int. Ed. 2015, 54, 12236; b)
O. R. Luca, R. H. Crabtree, Chem. Soc. Rev. 2013, 42, 1440; c) V.
Lyaskovskyy, B. de Bruin, ACS Catal. 2012, 2, 270
[13] F. E. McDonald, M. M. Gleason, J. Am. Chem. Soc. 1996, 118, 6648.
[14] A. Varela-Fernández, C. García-Yebra, J. A. Varela, M. A. Esteruelas,
C. Saá, Angew. Chem. Int. Ed., 2010, 49, 4278.
Keywords:
carboetherfication • enol ethers • heterocycles
synthetic
methods
•
iron
catalysis
•
[15] a) J. P. Perdew, Phys. Rev. B 1986, 33, 8822; b) A. D. Becke, Phys.
Rev. A 1988, 38, 3098; c) F. Weigend, R. Ahlrichs, Phys. Chem. Chem.
Phys. 2005, 7, 3297; d) Y. Zhao, D. G. Truhlar, Theor. Chem. Acc.
2008, 120, 215; e) J. Tomasi, B. Mennucci, R. Cammi, Chem. Rev.
2005, 105, 2999.
[1]
[2]
[3]
a) B. M. Trost, Science 1991, 254, 1471; b) B. M. Trost, Angew. Chem.
Int. Ed. 1995, 34, 259; c) Y. Hayashi, Chem. Sci. 2016, 7, 866.
R. M Bullock, Catalysis without Precious Metals, 2010, Wiley-VCH
Verlag GmbH & Co. KGaA, Weinheim, Germany.
a) B. Plietker, Iron Catalysis in Organic Chemistry: Reactions and
applications, Wiley-VCH, ed. 2, Weinheim, Germany, 2008; for
reviews on iron catalysis, see: b) C. Bolm, J. Legros, J. Le Paih, L.
Zani, Chem. Rev. 2004, 104, 6217; c) K. Gopalaiah, Chem. Rev.
2013, 113, 3248; d) I. Bauer, H.-J. Knölker, Chem. Rev. 2015, 115,
3170.
[16] Results at the M06/TZVP and PBE0-D3/TZVPP levels yield similar
energy profiles (see the ESI for further details).
[4]
For the synthesis of Fe1, See: a) H.-J. Knölker, J. Heber, C.H. Mahler,
Synlett 1992, 1002; b) A. J. Pearson, R. J. Shively, R. A. Dubbert,
Organometallics 1992, 11, 4096; for Fe2 see: c) S. Fleischer, S. S.
Zhou, K. Junge, M. Beller, Angew. Chem. Int. Ed. 2013, 52, 5120; for
Fe3 see: d) H.-J. Knölker, J. Heber, Synlett 1993, 924; for complex Fe4
see: e) S. Moulin, H. Dentel, A. Pagnoux-Ozherelyeva, S. Gaillard, A.
Poater, L. Cavallo, J.-F. Lohier, J.-L. Renaud, Chem. Eur. J. 2013, 19,
17881; For the synthesis of the complex Fe5 see: f) T.-T. Thai, D. S.
Mérel, A. Poater, S. Gaillard, J.-L. Renaud, Chem. Eur. J. 2015, 21,
7066; For the synthesis of the complex Fe6 see: g) S. V. Facchini, J.-M.
Neudörfl, L. Pignataro, M. Cettolin, C. Gennari, A. Berkessel, U. Piarulli
ChemCatChem 2017, 9, 1461; for the iron-mediated [2+2+1]
cycloaddition and the synthesis of the iron tricarbonyl complexes (also
complex Fe7), see: h) E. Weiss, W. Hübel, J. Inorg. Nucl. Chem. 1959,
11, 42; i) E. Weiss, R. Merényi, W. Hübel, Chem. Ber. 1962, 95, 1170;
for the synthesis of the Knölker’s iron hydride, see: j) H.-J. Knölker, E.
Baum, H. Goesmann, R. Klauss, Angew. Chem. Int. Ed. 1999, 38, 2064.
a) O. El-Sepelgy, N. Alandini, M. Rueping, Angew. Chem. Int. Ed. 2016,
55, 13602; b) O. El-Sepelgy, A. Brzozowska, M. Rueping,
ChemSusChem 2017, 10, 1664; c) K. P. J. Gustafson, A.
Guamundsson, K. Lewis, J.-E. Bäckvall, Chem. Eur. J. 2017, 23, 1048.
For seminal work on the use of the iron carbonyl complexes for
hydrogenation, see: a) C. P. Casey, H. Guan, J. Am. Chem. Soc.
[5]
[6]
2007, 129, 5816; b) C. P. Casey, H. Guan, J. Am. Chem. Soc. 2009
,
131, 2499: for hydrogen borrowing, see: c) T. Yan, B. L. Feringa, K.
Barta, Nat. Commun. 2014, 5, 5602; d) A. J. Rawlings, L. J.
Diorazio, M. Wills, Org. Lett. 2015, 17, 1086; For a recent review,
see: e) A. Quintard, J. Rodriguez, Angew. Chem. Int. Ed. 2014, 53,
4044.
[7]
[8]
For an elegant related ruthenium catalyzed cylcoisomerization of -
allenic alcohols to 2,3-dihydrofurans, see: B. Yang, C. Zhu, Y. Qiu,
J.-E. Bäckvall, Angew. Chem. Int. Ed. 2016, 55, 5568.
a) F. E. McDonald, K. S. Reddy, Y. Diaz, J. Am. Chem. Soc. 2000
,
122, 4304; b) F. E. McDonald, K. S. Reddy, Angew. Chem. Int. Ed.
2001, 40, 3653; c) F. E. McDonald, K. S. Reddy, J. Organomet.
Chem. 2001, 617–618, 444; d) P. Wipf, T. H. Graham, J. Org.
Chem. 2003, 68, 8798; e) M. H. Davidson, F. E. McDonald, Org.
Lett. 2004, 6, 1601; f) B. Koo, F. E. McDonald, Org. Lett. 2005, 7,
3621; g) S. B. Moilanena, D. S. Tan, Org. Biomol. Chem. 2005, 3,
798; h) B. Koo, F. E. McDonald, Org. Lett. 2007, 9, 1737;
[9]
a) B. Gockel, N. Krause, Org. Lett. 2006, 8, 4485; b) Y. Sawama, Y.
Sawama, N. Krause, Org. Biomol. Chem. 2008, 6, 3573; c) B. Gockel,
N. Krause, Eur. J. Org. Chem. 2010, 311.
[10] N. Krause, A. S. K. Hashmi, Modern Allene Chemistry, Vol 1 and 2,
2004, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany; , for
reviews, see: b) S. Ma, Acc. Chem Res. 2003, 36, 701; c) R.A.
This article is protected by copyright. All rights reserved.

10.1002/anie.201708240
Angewandte Chemie International Edition
COMMUNICATION
COMMUNICATION
Osama El-Sepelgy*, Aleksandra
Brzozowska, Luis Miguel Azofra, Yoon
Kyung Jang, Luigi Cavallo, and Magnus
Rueping
Page No. XXXX – Page No. XXXX
Page No. – Page No.
Experimental and computational study
of an unexpected iron catalyzed
carboetherfication by cooperative metal
and ligand substrate interaction
This article is protected by copyright. All rights reserved.