Cross-Coupling Reactions of Alkyl Halides with Aryl Grignard Reagents Using a Tetrachloroferrate with an Innocent Countercation

Article abstract of DOI:10.1002/adsc.201900568

Bis(triphenylphosphoranylidene)ammonium tetrachloroferrate, (PPN)[FeCl₄] (1), was evaluated as a catalyst for cross-coupling reactions. 1 exhibits high stability toward air and moisture and is an effective catalyst for the reaction of secondary alkyl halides with aryl Grignard reagents. The PPN cation is considered as an innocent counterpart to the iron center. We have developed an easy-to-handle iron catalyst for “ligand-free” cross-coupling reactions. (Figure presented.).

Full text of DOI:10.1002/adsc.201900568

Title: Cross-coupling Reactions of Alkyl Halides with Aryl Grignard
Reagents using a Tetrachloroferrate with an Innocent
Countercation
Authors: Toru Hashimoto, Tsubasa Maruyama, Takamichi Yamaguchi,
Yutaka Matsubara, and Yoshitaka Yamaguchi
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To be cited as: Adv. Synth. Catal. 10.1002/adsc.201900568
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10.1002/adsc.201900568
Advanced Synthesis & Catalysis
COMMUNICATION
DOI: 10.1002/adsc.201((will be filled in by the editorial staff))
Cross-coupling Reactions of Alkyl Halides with Aryl Grignard
Reagents using a Tetrachloroferrate with an Innocent
Countercation
Toru Hashimoto,a,* Tsubasa Maruyama,a Takamichi Yamaguchi,a Yutaka Matsubara,a
and Yoshitaka Yamaguchia,*
a
Department of Advanced Materials Chemistry, Graduate School of Engineering, Yokohama National University, 79-5
Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
Phone:(+81)-45-339-3932
Fax: (+81)-45-339-3932
E-mail: hashimoto-toru-kh@ynu.ac.jp and yamaguchi-yoshitaka-hw@ynu.ac.jp
Received: ((will be filled in by the editorial staff))
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201######.
Abstract.
Bis(triphenylphosphoranylidene)ammonium
So far, various catalyst systems have been
developed combining iron sources such as FeCl3 and
Fe(acac)3 with donor molecules such as amines,[7]
phosphines,[7h, 8] or N-heterocyclic carbenes (NHCs)[8a,
tetrachloroferrate, (PPN)[FeCl4] (1), was evaluated as a
catalyst for cross-coupling reactions. 1 exhibits high
stability toward air and moisture and is an effective catalyst
for the reaction of secondary alkyl halides with aryl
Grignard reagents. The PPN cation is considered as an
innocent counterpart to the iron center. We have developed
an easy-to-handle iron catalyst for “ligand-free” cross-
coupling reactions.
9, 10]
as ligands and/or additives.[11] In addition, well-
defined iron complexes also have been developed as
catalysts for the coupling reactions.[7h-7j, 8b-8i, 9d-9g, 11e,
11g]
Moreover, it has been reported that Fe(acac)3
itself acts as an effective catalyst for the coupling
reactions. Fe(acac)3 is commercially available and
stable toward air and moisture. It is thus an easy-to-
handle iron source for the preparation of iron
complexes and catalysts. While FeCl3 is arguably one
of the most basic iron sources, it is unfortunately
hydroscopic. Therefore, the development of easy-to-
handle iron sources for large-scale industrial
processes remains highly desirable.
Iron-containing imidazolium salts, generally
classified as ionic liquids, show high stability toward
air and moisture. In addition, these salts act as
efficient catalysts for cross-coupling reactions.[12, 13]
In these catalytic systems, the formation of iron-NHC
species as the catalytically active species by in-situ
deprotonation of the azolium cation with a Grignard
reagent cannot be ruled out.[8a, 9, 10] Therefore, we
were interested in the development of easy-to-handle
iron catalysts and the realization of “ligand-free” iron
catalysis for cross-coupling reactions. Herein, we
report the cross-coupling of alkyl halides with aryl
Keywords: Iron; ferrate salt; cross-coupling reaction; alkyl
halide; Grignard reagent
Transition-metal-catalyzed cross-coupling reactions
between organic electrophiles and organometallic
reagents represent one of the most powerful strategies
for the construction of carbon–carbon bonds.[1] Since
the discovery of cross-coupling reactions, palladium
and nickel complexes have been extensively studied
as catalysts, and continuous improvements have
resulted in the development of highly efficient
catalytic systems. Considerable attention has also
been focused on the use of iron catalysts in these
reactions, given that iron is an ideally suited practical
transition metal owing to its low cost, low toxicity,
and abundance.[2] The first discovery of FeCl3-
catalyzed cross-coupling reactions was reported by
Kochi in 1971.[3] In 1998, Cahiez used an iron/NMP
(NMP = N-methylpyrrolidinone) system, in which
NMP serves as a co-solvent that has a beneficial
impact on reactions involving alkenyl electrophiles.[4]
Subsequently, Fürstner improved this Fe(acac)3/NMP
(acac = 2,4-pentanedionato) system for reactions
using aryl chlorides and triflates.[5, 6]
R1
R2
R1
R2
1
BrMg R3
+
Br
R3
CPME
Scheme 1. The cross-coupling reactions catalyzed by
(PPN)[FeCl4] (1) reported in this work.
1
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10.1002/adsc.201900568
Advanced Synthesis & Catalysis
Grignard reagents catalyzed by (PPN)[FeCl4] (1), i.e.,
a tetrachloroferrate bearing the innocent cation
bis(triphenylphosphoranylidene)ammonium (PPN),
(Scheme 1).
Table 1. Optimization of the conditions for the cross-
coupling of bromocyclohexane (2a) with phenylmagnesium
bromide catalyzed by 1[a]
1 (5 mol%)
Br
+
BrMg
Tetrachloroferrate 1 was prepared according to a
Solvent, rt, 1 h
literature method,[14] i.e., by treating anhydrous FeCl3
2a
(1.2 equiv)
3a
with
an
equimolar
amount
of
Biphenyl
(%)[c]
Recovery
of 2a (%)
bis(triphenylphosphoranylidene)ammonium chloride
((PPN)Cl) in MeOH at room temperature. Salt 1 was
obtained in 91% yield as a yellow solid (Scheme 2)
and characterized by elemental analyses and X-ray
diffraction study (Figure 1). Interestingly, 1 is not
3a (%)[b]
Entry Solvent
1
2
3
4
5
6
THF
26
27
22
58
28
34
94
88
36
17
14
25
22
38
10
11
33
55
58
12
56
38
0
THF/NMP[d]
NMP
Et2O
MTBE
DME
CPME
CPME
hydroscopic and highly stable toward atmospheric air
16]
and moisture.[15,
Moreover, 1 showed good
solubility in THF and NMP, whereas it was poorly
soluble in ethereal solvents such as Et2O, tert-butyl
methyl ether (MTBE), 1,2-dimethoxyethane (DME),
and cyclopentyl methyl ether (CPME).
7
8[e]
0
[a]
The reaction was carried out using 2a (0.5–1.0 mmol) and
PhMgBr (0.6–1.2 mmol, 1.2 equiv) in the presence of 1 (5 mol%)
[b]
at room temperature. The yield of 3a is based on 2a and was
determined by gas-liquid chromatography (GLC) analysis using
PPh3
PPh3
PPh3
PPh3
[c]
undecane as the internal standard.
The yield of biphenyl is
N
Cl
+
FeCl3
N
[FeCl4]
based on PhMgBr and was determined by GLC analysis using
MeOH, rt
[d]
[e]
undecane as the internal standard.
THF/NMP = 9/1 (v/v).
1, 91%
The reaction (7.0 mmol scale) was carried out for 1.5 h using 1
mol% of 1.
Scheme 2. Preparation of catalyst (PPN)[FeCl4] (1).
Table 2. Substrate scope of the cross-coupling reaction of
alkyl halides with aryl Grignard reagents catalyzed by 1[a]
R
R
1 (5 mol%)
+
Alkyl
X
BrMg
Alkyl
CPME, rt
2
(1.2–1.5 equiv)
3
X = Br, I ,Cl
Yield (%)[b]
3
Entry
Alkyl–X
2
Coupling product
P1
N1
1
2
3
4
2a
2a
2a
2a
3b 95 (R = Me)
3c 90 (R = OMe)
3d 78 (R = NMe2)
3e 63 (R = F)
Br
R
69 (X = I)[c]
41 (X = Cl)[c]
5
6
2b
2c
3a
3a
X
Cl2
P2
Cl1
7
2d
3f 50
Br
Fe1
Cl3
Me
Me
Me
Cl4
8
9
2e
2f
81 (X = Br)
53 (X = I)
3g
Ph
Ph
X
Me
10
11
2g
2a
3h 72
TBSO
Figure 1. ORTEP drawing of (PPN)[FeCl4] (1) with thermal
ellipsoids at 30% probability. All hydrogen atoms have been
omitted for clarity.
TBSO
Br
Br
Me
3i 46
In order to evaluate the catalytic activity of 1, the
cross-coupling reaction of bromocyclohexane (2a)
with 1.2 equivalents of phenylmagnesium bromide
was carried out in the presence of 5 mol% of 1 in
various solvents (Table 1). In the case of THF, the
cross-coupled product, phenylcyclohexane (3a), was
obtained in 26% yield, together with the homo-
coupled product from phenylmagnesium bromide
(biphenyl) in 36% yield (entry 1). In this case, 33%
of the starting material (2a) was recovered. When the
mixed solvent THF/NMP (9/1; v/v) was used, 3a was
obtained in 27% yield (entry 2). Using NMP as the
12
13
2h
2i
3j
3j
30 (X = Br)
32 (X = I)
C10H21
X
C10H21
[a]
The reaction was carried out using alkyl halides 2 (0.5–1.0
mmol) and an aryl Grignard reagent (1.2–1.5 equiv) in the
presence of 1 (5 mol%) at room temperature. Isolated yield.
The yield of 3a is based on 2b or 2c and was determined by GLC
analysis using undecane as the internal standard.
[b]
[c]
solvent furnished 3a in 22% yield (entry 3).
Subsequently, we investigated the reaction the
aforementioned ethereal, albeit that 1 is poorly
soluble in these solvents. In Et2O, the yield of 3a
2
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10.1002/adsc.201900568
Advanced Synthesis & Catalysis
increased to 58% yield, but the reaction did not reach
completion (entry 4). MTBE and DME were not
suitable solvents, i.e., 3a was obtained merely in low
yield (28% and 34%; entries 5 and 6). As shown in
entry 7, CPME provided the best results, affording 3a
in 94% yield together with small amounts of biphenyl
(10% yield based on PhMgBr). This catalytic
protocol based on 1 was also successful on the gram-
scale (7 mmol of 2a). In this case, the reaction
proceeded efficiently to give 3a in 88% yield, even
when the amount of 1 was reduced to 1 mol% (entry
8).
stereoisomers 3l in 69% yield (trans:cis = 74:26). In
the case of 2k, the simple coupled product 3m was
not detected, whereas ring-opened product 3n was
obtained in 13% yield. Overall, these results indicated
that the cross-coupling reaction catalyzed by 1 likely
involves radical species.[7b, 8a, 8c, 8e, 8g]
1 (6 mol%)
BnO
Br
BnO
+
BrMg
CPME, rt, 24 h
2j
trans/cis = >99:1
(1.5 equiv)
3l, 69%
(trans/cis = 74/26)
To demonstrate the efficiency of 1 as a catalyst for
such cross-coupling reactions, we investigated the
substrate scope with a variety of alkyl halides and
aryl Grignard reagents under the optimized reaction
conditions, and the results are summarized in Table 2.
Using p-tolylmagnesium bromide, 3b was obtained in
95% yield (entry 1). p-Methoxyphenylmagnesium
bromide afforded 3c in 90% yield (entry 2), while p-
dimethylaminophenylmagnesium bromide furnished
a slightly lower yield of 3d (78%, entry 3). p-
Fluorophenylmagnesium bromide, which bears an
electron-withdrawing substituent, afforded 3e in 63%
yield (entry 4). Next, we investigated the influence of
different electrophiles. The reaction between
iodocyclohexane (2b) and PhMgBr furnished 3a in
69% yield (entry 5). In the case of chlorocyclohexane
(2c), the yield of 3a decreased to 41% (entry 6).
Bromocycloheptane (2d) was also tolerated as a
coupling partner, affording 3f in 50% yield (entry 7).
The reaction of acyclic alkyl bromide 2e generated 3g
in 81% yield, whereas the iodo analogue 2f provided
3g in 53% yield (entries 8 and 9). As shown in entry
10, the siloxy substituent on the alkyl chain remained
intact and the product was obtained in 72% yield. o-
Tolylmagnesium bromide gave the corresponding
product 3i in moderate yield[7h] (entry 11). We next
examined the reaction with primary alkyl halides.
The reaction using 1-bromodecane (2h) proceeded
sluggishly to give coupling product 3j in 30% yield
under concomitant formation of decane (15%) and 1-
decene (40%). Furthermore, 15% of bromide 2h was
recovered (entry 12). In the case of 1-iododecane (2i),
the corresponding product (3j) was obtained in 32%
yield.[17] Moreover, benzylmagnesium bromide
furnished 3k in 75% yield (Scheme 3).[8b, 8g-8i]
Scheme 4. Coupling reaction of 2j with PhMgBr catalyzed
by 1.
3m, n.d.
1 (5 mol%)
+
BrMg
+
Br
CPME, rt, 1 h
2k
(1.2 equiv)
3n, 13%
Scheme 5. Coupling reaction of 2k with PhMgBr catalyzed
by 1: radical clock experiment.
Furthermore, we examined the isolation of any
potentially formed iron species. However, all
attempts to obtain such species were unsuccessful.
Although the actual structure of the intermediates in
our catalytic system is not clear at this point, we
assume that the [FeCl4]– anion of 1 plays an
important role in the catalytic cycle. When other iron
salts such as FeCl3, FeCl2, or Fe(acac)3 were
employed as catalysts under otherwise identical
reaction conditions, the coupled product 3a was
obtained in 90%, 93%, and 94% yield, respectively
(Scheme 6). These results indicate that both 1 and
these other iron compounds afford similarly active
iron species via the reduction of a Grignard reagent in
the catalytic cycle. Accordingly, we assume that the
PPN cation in 1 does not engage in the catalytic
reaction, i.e., the PPN cation can be considered as an
innocent counterpart to the iron center.
Fe cat. (5 mol%)
+
Br
BrMg
1 (5 mol%)
BrMg
CPME, rt, 1 h
Br
+
CPME, rt, 1 h
2a
(1.2 equiv)
3a
2a
(1.5 equiv)
3k, 75%
FeCl3
FeCl2
Fe(acac)3
:
:
90%
93%
94%
:
Scheme 3. Coupling reaction of 2a with benzylmagnesium
bromide catalyzed by 1.
Scheme 6. Cross-coupling reactions using iron salts in CPME.
To gain insight into the reaction mechanism,[18] we
In conclusion, we have reported (PPN)[FeCl4] (1)
as an efficient catalyst for the coupling of secondary
alkyl halides with aryl and benzyl Grignard reagents
under mild reaction conditions. 1 exhibits high
stability toward air and atmospheric moisture. The
investigated the coupling reaction using trans-4-
benzyloxycyclohexyl
bromide
(2j)
and
(bromomethyl)cyclopropane (2k) as electrophiles
under standard conditions (Schemes 4 and 5).
Treatment of 2j with PhMgBr afforded a mixture of
3
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10.1002/adsc.201900568
Advanced Synthesis & Catalysis
results described in this paper may thus promote the
development of “ligand-free” iron-catalyzed reactions.
Further investigations into the (i) mechanistic aspects
of this catalytic system, including the role of the
countercation, ferrate, and the solvent, (ii) the
coupling of various organometallic reagents with
organic electrophiles, and (iii) the development of
novel organic transformations are currently in
progress in our group.
778−789. f) A. Piontek, E. Bisz, M. Szostak, Angew.
Chem. 2018, 130, 11284–11297; Angew. Chem., Int. Ed.
2018, 57, 11116–11128.
[3] a) M. Tamura, J. K. Kochi, J. Am. Chem. Soc. 1971, 93,
1487–1489; b) S. M. Smith, J. K. Kochi, J. Org. Chem.
1975, 40, 599–606; c) R. S. Smith, J. K. Kochi, J. Org.
Chem. 1976, 41, 502–509.
[4] G. Cahiez, H. Avedissian, Synthesis 1998, 119–1205.
[5] a) A. Fürstner, A. Leitner, Angew. Chem. 2002, 114,
632–635; Angew. Chem., Int. Ed. 2002, 41, 609–612;
b) A. Fürstner, A. Leitner, M. Méndez, H. Krause, J.
Am. Chem. Soc. 2002, 124, 13856–13863; c) A.
Fürstner, H. Krause, C. W. Lehmann, Angew. Chem.
2006, 118, 454–458; Angew. Chem., Int. Ed. 2006, 45,
440–444.
Experimental Section
Preparation for (PPN)[FeCl4] (1): A Schlenk tube was
charged with anhydrous FeCl3 (0.608 g, 3.75 mmol),
bis(triphenylphosphoranylidene)ammonium
chloride
((PPN)Cl, 2.18 g, 3.80 mmol) and dry MeOH (45 mL) at
room temperature. After stirring overnight, the solvent was
removed in vacuo to give a yellow residue that was washed
with Et2O (4 × 10 mL) and dissolved in THF (20 mL). The
solution was filtered through a pad of Celite and
concentrated in vacuo. The residue was washed with
hexane to give 1 as a yellow solid (2.50 g, 91%). IR
(Diamond-ATR, neat): 2359, 1436, 1264, 1182, 1112,
1027, 997, 720, 688, 530, 495, 373 cm–1. Anal. calcd for
C36H30Cl4FeNP2, C, 58.73; H, 4.11; N, 1.90, found C,
58.74; H, 4.12; N, 1.84.
[6] It has been reported that NMP can interact with the
magnesium centers in iron-catalyzed cross-coupling
reactions; for details, see: S. B. Muñoz III, S. L.
Daifuku, J. D. Sears, T. M. Baker, S. H. Carpenter, W.
W. Brennessel, M. L. Neidig, Angew. Chem. 2018, 130,
6606–6610; Angew. Chem., Int. Ed. 2018, 57, 6496–
6500.
[7] a) M. Nakamura, K. Matsuo, S. Ito, E. Nakamura, J.
Am. Chem. Soc. 2004, 126, 3686–3687; b) R. B.
Bedford, D. W. Bruce, R. M. Frost, M. Hird, Chem.
Commun. 2005, 4161–4163; c) G. Cahiez, V. Habiak,
C. Duplais, A. Moyeux, Angew. Chem. 2007, 119,
4442–4444; Angew. Chem. Int. Ed. 2007, 46, 4364–
4366.; d) A. Guérinot, S. Reymond, J. Cossy, Angew.
Chem. 2007, 119, 6641–6644; Angew. Chem. Int. Ed.
2007, 46, 6521–6524.; e) S. Ito, Y. Fujiwara, E.
Nakamura, M. Nakamura, Org. Lett. 2009, 11, 4306–
4309; f) T. Hatakeyama, N. Nakagawa, M. Nakamura,
Org. Lett. 2009, 11, 4496–4499; g) S. E. Denmark, A. J.
Cresswell, J. Org. Chem. 2013, 78, 12593–12628; h)
C.-L. Sun, H. Krause, A. Fürstner, Adv. Synth. Catal.
2014, 356, 1281–1291; i) R. B. Bedford, P. B. Brenner,
D. Elorriaga, J. N. Harvey, J. Nunn, Dalton Trans.
2016, 45, 15811–15817; j) Y. Matsubara, T.
Yamaguchi, T. Hashimoto, Y. Yamaguchi, Polyhedron,
2017, 128, 198–202.
General procedure for the cross-coupling reactions: A
Schlenk tube was charged with 1 (5 mol%), CPME (5 mL),
the respective alkyl halide (0.50 mmol), and a Grignard
reagent (1.2–1.5 equiv) at room temperature. The coupling
reaction was carried out at room temperature for 1–24 h.
After quenching with HCl (1 M, 2.0 mL), the aqueous
layer was extracted with Et2O (5 × 3 mL). The combined
organic layers were washed with brine (5 mL) and dried
over anhydrous MgSO4. After filtration and removal of all
volatiles from the filtrate, the residue was purified by
column chromatography on silica gel.
Acknowledgements
This work was supported by a Chugai Award in Synthetic
Organic Chemistry, Japan, and JSPS KAKENHI grant
JP17K05805. This work was also supported by the
Collaborative Research Program of the Institute for
Chemical Research, Kyoto University (grant 2018-24). The
authors are grateful to Mr. Shinji Ishihara (Yokohama Natl.
Univ.) for carrying out the elemental analyses and Dr.
Takahiro Iwamoto and Prof. Masaharu Nakamura (Kyoto
Univ.) for their kind help with the HRMS measurements.
We thank Zeon Co., Ltd. for their generous donation of
CPME. We also thank Hokko Chemical Industry Co., Ltd.
for the generous supply of 4-fluorophenylmagnesium
bromide.
[8] a) R. B. Bedford, M. Betham, D. W. Bruce, A. A.
Danopoulos, R. M. Frost, M. Hird, J. Org. Chem. 2006,
71, 1104–1110; b) R. B. Bedford, M. Huwe, M. C.
Wilkinson, Chem. Commun. 2009, 600–602; c) T.
Hatakeyama, Y. Kondo, Y. Fujiwara, H. Takaya, S. Ito,
E. Nakamura, M. Nakamura, Chem. Commun. 2009,
1216–1218; d) R. B. Bedford, M. A. Hall, G. R.
Hodges, M. Huwe, M. C. Wilkinson, Chem. Commun.
2009, 6430–6432; e) T. Hatakeyama, Y. Fujiwara, Y.
Okada, T. Itoh, T. Hashimoto, S. Kawamura, K. Ogata,
H. Takaya, M. Nakamura, Chem. Lett. 2011, 40, 1030–
1032; f) S. Kawamura, T. Kawabata, K. Ishizuka, M.
Nakamura, Chem. Commun. 2012, 48, 9376–9378; g) T.
Hatakeyama, T. Hashimoto, Y. Kondo, Y. Fujiwara, H.
Seike, H. Takaya, Y. Tamada, T. Ono, M. Nakamura, J.
Am. Chem. Soc. 2010, 132, 10674–10676; h) R. B.
Bedford, P. B. Brenner, E. Carter, T. W. Carvell, P. M.
Cogswell, T. Gallagher, J. N. Harvey, D. M. Murphy, E.
References and Notes
[1] Metal-Catalyzed Cross-Coupling Reactions, 2nd ed.
(Eds.; A. de Meijere, F. Diederich), Wiley-VCH:
Weinheim, 2004.)
[2] For reviews, see: a) C. Bolm, J. Legros, J. L. Paih, L.
Zani, Chem. Rev. 2004, 104, 6217–6254; b) B. D.
Sherry, A. Fürstner, Acc. Chem. Res. 2008, 41, 1500–
1511; c) W. M. Czaplik, M. Mayer, J. Cvengros, A. J.
von Wangelin, ChemSusChem 2009, 2, 396–417; d) R.
Jana, T. P. Pathak, M. S. Sigman, Chem. Rev. 2011,
111, 1417–1492; e) A. Fürstner, ACS Cent. Sci. 2016, 2,
4
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10.1002/adsc.201900568
Advanced Synthesis & Catalysis
C. Neeve, J. Nunn, D. R. Pye, Chem.-Eur. J. 2014, 20,
[13] a) H.-H. Gao, C.-H. Yan, X.-P. Tao, Y. Xia, H.-M.
Sun. Q. Shen, Y. Zhang, Organometallics 2010, 29,
4189–4192; b) C.-H. Yan, L. Wang, H. Gao, H. Sun, S.
Qi, Chin. Sci. Bull. 2012, 57, 1953–1958; c) H.-N.
Deng, T.-L. Xing, C.-L. Xia, H.-M. Sun. Q. Shen, Y.
Zhang, Dalton Trans. 2012, 41, 11597–11607; d) Y.
Xia, C.-H. Yan, Z. Li, H.-H. Gao, H.-M. Sun. Q. Shen,
Y. Zhang, Chin. Sci. Bull. 2013, 58, 493–499; e) L.-L.
Wang, B. Lu, A.-D. Zhu, H.-M. Sun, Q. Shen. Chin.
Sci. Bull. 2013, 58, 3624–3629; f) C.-L. Xia, C.-F. Xie,
Y.-F. Wu, H.-M. Sun, Q. Shen, Y. Zhang, Org. Biomol.
Chem. 2013, 11, 8135–8144.
7935–7938; i) R. B. Bedford, P. B. Brenner, E. Carter,
J. Clifton, P. M. Cogswell, N. J. Gower, M. F. Haddow,
J. N. Harvey, J. A. Kehl, D. M. Murphy, E. C. Neeve,
M. L. Neidig, J. Nunn, B. E. R. Snyder, J. Taylor,
Organometallics 2014, 33, 5767–5780; j) M. Jin, L.
Adak, M. Nakamura, J. Am. Chem. Soc. 2015, 137,
7128−7134; k) T. Iwamoto, C. Okuzono, L. Adak, M.
Jin, M. Nakamura, Chem. Comm. 2019, 55, 1128–1131.
[9] a) S. K. Ghorai, M. Jin, T. Hatakeyama, M. Nakamura,
Org. Lett. 2012, 14, 1066–1069; b) Z. Mo, Q. Zhang, L.
Deng, Organometallics 2012, 31, 6518–6521; c) R.
Agata, T. Iwamoto, N. Nakagawa, K. Isozaki, T.
Hatakeyama, H. Takaya, M. Nakamura, Synthesis,
2015, 47, 1733–1740; d) Y. Liu, J. Xiao, L. Wang, Y.
Song, L. Deng, Organometallics, 2015, 34, 599–605; e)
X. Wang, J. Zhang, L. Wang, L. Deng,
Organometallics, 2015, 34, 2775-2782; f) J. A.
Przyojski, K. P. Veggeberg, H. D. Arman, Z. J.
Tonzetich, ACS Catal. 2015, 5, 5938–5946; g) S. B.
Muñoz, V. E. Fleischauer, W. W. Brennessel, M. L.
Neidig, Organometallics, 2018 37, 3093–3101.
[14] G. P. Algra, S. Balt, Inorg. Chem. 1981, 20, 1102–
1106.
[15] For details, see the Supporting Information.
[16] The crystallographic data can be obtained free of
charge from The Cambridge Crystallographic Data
Centre under reference number CCSC 1893663.
[17] In this reaction, decane (20%) and 1-decene (31%)
were formed, while iodide 2i was recovered in 17%.
[18] For recent mechanistic studies on iron-catalyzed
cross-coupling reactions of alkyl halides, see: a) D.
Noda, Y. Sunada, T. Hatakeyama, M. Nakamura, H.
Nagashima, J. Am. Chem. Soc. 2009, 131, 6078–6079;
b) R. B. Bedford, P. B. Brenner, E. Carter, P. M.
Cogswell. M. F. Haddow, J. N. Harvey, D. M. Murphy,
J. Nunn, C. H. Woodall. Angew. Chem. 2014, 126,
1835–1839; Angew. Chem. Int. Ed. 2014, 53, 1804–
1808; c) J. D. Sears, P. G. N. Neate, M. L. Neidig, J.
Am. Chem. Soc. 2018, 140, 11872–11883; d) S. L.
Daifuku, M. H. Al-Afyouni, B. E. R. Snyder, J. L.
Kneebone, M. L. Neidig, J. Am. Chem. Soc. 2014, 136,
9132−9143; e) S. L. Daifuku, J. L. Kneebone, B. E. R.
Snyder, M. L. Neidig, J. Am. Chem. Soc. 2015, 137,
11432 − 11444; f) H. Takaya, S. Nakajima, N.
Nakagawa, K. Isozaki, T. Iwamoto, R. Imayoshi, N. J.
Gower, L. Adak, T. Hatakeyama, T. Honma, M.
Takagaki, Y. Sunada, H. Nagashima, D. Hashizume, O.
Takahashi, M. Nakamura, Bull. Chem. Soc. Jpn. 2015,
88, 410–418, and the references cited therein.
[10] a) T. Hatakeyama, M. Nakamura, J. Am. Chem. Soc.
2007, 129, 9844–99845; b) T. Hatakeyama, S.
Hashimoto, K. Ishizuka, M. Nakamura, J. Am. Chem.
Soc. 2009, 131, 11949–11963; c) Y.-Y. Chua, H. A.
Duong, Chem. Commun. 2014, 50, 8424–8427; d) Y.-Y.
Chua, H. A. Duong, Chem. Commun. 2016, 52, 1466–
1469.
[11] a) T. Nagano, T. Hayashi, Org. Lett. 2004, 6, 1297–
1299; b) R. B. Bedford, D. W. Bruce, R. M. Frost, J. W.
Goodby, M. Hird, Chem. Commun. 2004, 2822–2823;
c) R. Martin, A. Fürstner, Angew. Chem. 2004, 116,
4045–4047; Angew. Chem. Int. Ed. 2004, 43, 3955–
3949; d) A. Fürstner, R. Martin, H. Krause, G. Seidel,
R. Goddard, C. W. Lehmann, J. Am. Chem. Soc. 2008,
130, 8773–8787; e) Y. Yamaguchi, H. Ando, M.
Nagaya, H. Hinago, T. Ito, M. Asami, Chem. Lett. 2011,
40, 983–985; f) M, Jin, M. Nakamura, Chem. Lett.
2011, 40, 1012–1014; g) G. Bauer, C. W. Cheung, X.
Hu, Synthesis 2015, 47, 1726–1732.
[12] K. Bica, P. Gaertner, Org. Lett. 2006, 8, 733–735.
5
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10.1002/adsc.201900568
Advanced Synthesis & Catalysis
COMMUNICATION
R1
R2
Cross-coupling Reactions of Alkyl Halides with
Aryl Grignard Reagents using a Tetrachloroferrate
with an Innocent Countercation
PPh3
PPh3
Br
N
[FeCl4]
R1
R3
R2
+
CPME
Adv. Synth. Catal. Year, Volume, Page – Page
BrMg R3
R3 = Aryl, Bn
up to 95%
Toru Hashimoto,* Tsubasa Maruyama, Takamichi,
Yamaguchi, Yutaka Matsubara, and Yoshitaka
Yamaguchi*
• Air- and moisture stable salt • Mild reaction conditions
• Easy preparation
• Ligand free
• Radical pathway
6
This article is protected by copyright. All rights reserved.