Nickel-catalyzed carboxylation of aryl and vinyl chlorides employing carbon dioxide

Article abstract of DOI:10.1021/ja303514b

Nickel-catalyzed carboxylation of aryl and vinyl chlorides employing carbon dioxide has been developed. The reactions proceeded under a CO₂ pressure of 1 atm at room temperature in the presence of nickel catalysts and Mn powder as a reducing agent. Various aryl chlorides could be converted to the corresponding carboxylic acid in good to high yields. Furthermore, vinyl chlorides were successfully carboxylated with CO₂. Mechanistic study suggests that Ni(I) species is involved in the catalytic cycle.

Full text of DOI:10.1021/ja303514b

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Communication
Nickel-Catalyzed Carboxylation of Aryl and
Vinyl Chlorides Employing Carbon Dioxide
Tetsuaki Fujihara, Keisuke Nogi, Tinghua Xu, Jun Terao, and Yasushi Tsuji
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/ja303514b • Publication Date (Web): 21 May 2012
Downloaded from http://pubs.acs.org on May 22, 2012
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Nickel-Catalyzed Carboxylation of Aryl and Vinyl Chlorides Employing Carbon
Dioxide
Tetsuaki Fujihara, Keisuke Nogi, Tinghua Xu, Jun Terao and Yasushi Tsuji*
Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University,
Nishikyo-ku, Kyoto 615-8510, Japan.
RECEIVED DATE (automatically inserted by publisher); ytsuji@scl.kyoto-u.ac.jp
ABSTRACT: The nickel-catalyzed carboxylation of aryl and vinyl
chlorides employing carbon dioxide (CO2) has been developed.
The reactions proceeded under a CO2 pressure of 1 atm at room
temperature in the presence of nickel catalysts and Mn powder as
a reducing agent. Various aryl chlorides could be converted to the
corresponding carboxylic acid in good to high yields. Furthermore,
vinyl chlorides were successfully carboxylated with CO2.
Mechanistic study suggests that Ni(I) species is involved in the
catalytic cycle.
Table 1. Nickel-Catalyzed Carboxylation of 1a Employing Carbon
16
17
18
19
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21
2
23
24
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26
27
28
29
30
31
32
3
34
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43
4
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50
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52
53
54
5
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60
Dioxidea
Entry
Catalyst System: alteration from Yield of
Yield of
the standard conditions
2a-Me (%)b 3a (%)b
1
Standard conditions
95 (84)c
0
2
3
4
5
6
7
8
9
Without added PPh3
53
0
--
27
0
trace
0
trace
0
0
0
0
27
0
Carbon dioxide (CO2) is an ideal C1 source owing to its
abundance, low cost, non-toxicity, and good potential as a
renewable source.1 However, it is not easy to activate such a
thermodynamically and kinetically stable material. Therefore, the
efficient conversion of CO2 with the aid of transition-metal
catalysts is highly appropriate.2 In particular, the
hydrocarboxylation of carbon–carbon unsaturated compounds
such as alkynes,3a,b alkenes3c and 1,2- and 1,3-dienes3d,e is very
promising. In addition, the carboxylation reactions of arylzinc4
and arylboronic esters5 with CO2 have been studied intensively,
since in these reactions various functionalities that are not
compatible with Grignard reagents were tolerant. However, these
zinc and boron compounds must be prepared from the
corresponding aryl halides prior to the catalytic reactions. Thus,
the direct carboxylation of the parent aryl halides is most
desirable as this is a more straightforward transformation.6
Without NiCl2(PPh3)2
Without CO2 (under Ar)
Without Mn powder
Without Et4NI
P(4-MeOC6H4)3 in place of PPh3
PCy3 in place of PPh3
dppe in place of PPh3
bpy in place of PPh3
Zn in place of Mn
Mg in place of Mn
0
trace
53
0
0
0
d
d
e
e
10
11
12
9
0
a
Reaction conditions; 1-butyl-4-chlorobenzene (1a, 0.50 mmol),
NiCl2(PPh3)2 (0.025 mmol, 5.0 mol %), PPh3 (0.050 mmol, 10 mol %),
Mn powder (1.5 mmol, 3.0 equiv), Et4NI (0.050 mmol, 10 mol %), in
DMI (0.75 mL), at 25 ºC for 20 h. b Determined by GC analysis. c Isolated
yield of 2a. A mixture of NiCl2L2 (0.025 mmol) and added L (0.050
mmol) were used as the catalyst: L = P(4-MeOC6H4)3 or PCy3.
d
e
A
mixture of NiCl2L' (0.025 mmol) and L' (0.025 mmol) were used as the
catalyst: L' = dppe or bpy.
The catalytic carboxylation of aryl halides employing CO2
was first developed as electrochemical reactions in the presence
of nickel7a-c and palladium catalysts.7d,e Unfortunately, these were
not efficient synthetic methods, and the scope of possible
substrates was quite restricted. Later, the non-electrochemical
carboxylation of aryl bromides and chlorides using CO2 was
carried out in the presence of stoichiometric amounts of Ni(0)
complexes.8 Recently, the carboxylation of aryl bromides
employing CO2 was performed catalytically using a palladium
complex as the catalyst.9 However, in this reaction, the catalytic
activity was not satisfactory, since 1) the more reactive aryl
bromides should be employed as substrates, while the less
reactive and more accessible aryl chlorides did not react at all; 2)
the reaction must be carried out under a CO2 pressure of 10 atm at
40 ºC to achieve good yields; 3) the highly reactive and
pyrophoric ZnEt2 must be employed as the reducing agent; 4)
large amounts (up to 17%) of arenes were inevitably formed as
by-products through hydrogenative debromination. Herein, we
report a much more efficient catalytic reaction, in which a less
noble nickel catalyst is highly active in the carboxylation of aryl
chlorides as well as vinyl chlorides under a CO2 pressure of 1 atm
at room temperature, with easy-to-handle Mn powder used as the
reducing agent.
The reaction of 1-butyl-4-chlorobenzene (1a) was carried out
using a mixture of NiCl2(PPh3)2 (5.0 mol %) and added PPh3 (10
mol %) as a catalyst with Mn powder (Aldrich, 99.99%, 3.0
equiv) as a reducing agent, in the presence of Et4NI (10 mol %) in
1,3-dimethyl-2-imidazolidinone (DMI) at 25 ºC under a CO2
pressure of 1 atm (Table 1). The yield of 4-butylbenzoic acid (2a)
was determined by gas chromatography (GC) analysis after
derivatization to the corresponding methyl ester (2a-Me).10 Under
standard conditions, 2a-Me was obtained in 95% yield. Unlike
the Pd-catalyzed reaction,9 only a small amount (< 5%) of
butylbenzene was afforded. Compound 2a was isolated from the
reaction mixture in 84% yield (entry 1). Without the added PPh3
(i.e., with only NiCl2(PPh3)2 as the catalyst), the yield of 2a-Me
was reduced to 53% and the biaryl (3a) was obtained in 27%
yield (entry 2). In the absence of NiCl2(PPh3)2, 1a was not
converted, and 2a-Me and 3a were not obtained at all (entry 3).
When the reaction was carried out under an Ar atmosphere, 1a
was not converted (entry 4).11 These results clearly indicated that
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Scheme 1. Nickel-Catalyzed Carboxylation of Vinyl Chloridesa
Table 2.
Nickel-Catalyzed Carboxylation of Various Aryl
Chlorides and Other Derivativesa
1
2
3
4
5
6
7
8
9
10
1
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Entry
1c
Substrate 1
Product 2
Yield (%)b
90
1b
1c
2b
2c
3
74
81
2c
Scheme 2. Stoichiometric Reactions Relevant to Mechanism
2d
1d
1e
1f
4
78
87
76
2e
2f
5
6c
2g
2h
1g
1h
7
8
82
72
1i
2i
9d
58
yield of 2a-Me decreased considerably (entry 7). Other ligands
such as tricyclohexylphosphine (PCy3), 1,2-
2j
1j
10e
11
52
80
2k
1k
diphenylphosphinoethane (dppe), and 2,2’-bipyridine (bpy)
suppressed the carboxylation completely (entries 8–10). Other
reducing agents such as Zn powder or Mg turning gave either a
low product yield or no product (entries 11 and 12). In DMF as
the solvent, 2a-Me was obtained in 64% yield with the formation
of 3a (9%). The reaction in THF afforded 2a-Me and 3a in 7%
and 22% yields, respectively, while in toluene, the reaction did
not proceed at all.
The carboxylation of various aryl chlorides (1b–k) was
carried out (Table 2). Aryl chlorides bearing both electron-rich
(entry 1) and electron-poor (entries 2 and 3) moieties gave the
corresponding carboxylic acids (2b–d) in high yields. 2-
2l
1l
1m
1n
12f
13f
14f
2l
2l
73
72
51
2o
1o
Chloronaphthalene and an aryl chloride bearing
a tert-
a Reaction conditions; 1 (0.50 mmol), NiCl2(PPh3)2 (0.025 mmol, 5.0
mol %), PPh3 (0.050 mmol, 10 mol %), Mn powder (1.5 mmol, 3.0
equiv), Et4NI (0.050 mmol, 10 mol %), in DMI (0.75 mL), at 25 ºC for
butyldimethylsilyl (TBS) group provided the corresponding
carboxylic acids in good yields (entries 4 and 5). Gratifyingly,
ester (entries 6 and 7) and amide (entry 8) functionalities, which
were not tolerated with organomagnesium and organolithium
reagents, remained intact under the present reaction conditions. A
boronic acid ester (entry 9) and a thiophene ring (entry 10) were
also found to be compatible functionalities. An aryl bromide (1l)
gave the corresponding carboxylic acid (2l) in 80% yield (entry
11). Aryl tosylate (1m) and triflates13 (1n and 1o) also provided
the corresponding carboxylic acids at 60 ºC (entries 12–14).
Unfortunately, ortho-substituted aryl chlorides and aryl chlorides
bearing hydroxyl group or amino groups could not be used as
substrates.
20 h. b Isolated yield. A mixture of NiCl2{P(4-MeOC6H4)3)}2 (0.025
c
mmol, 5.0 mol %) and P(4-MeOC6H4)3 (0.050 mmol, 10 mol %) were
used as the catalyst at 40 oC for 24 h. d At 35 oC for 24 h. e At 35 oC for
f
30 h. NiCl2(PPh3)2 (0.050 mmol, 10 mol %), PPh3 (0.10 mmol, 20
mol %), Mn powder (1.5 mmol, 3.0 equiv), Et4NI (0.1 mmol, 20 mol %),
in DMI (0.75 mL), at 60 ºC for 20 h.
the arylmanganese species would not be formed through the
reactions of aryl chlorides with Mn powder, either in the absence
or presence of a nickel catalyst. The Mn powder was essential and
no reaction would proceed without it (entry 5). Et4NI was also
indispensable for the carboxylation (entry 6). When Et4NBr and
Et4NCl were used in place of Et4NI, no conversion of 1a was
observed. Employing a mixture of NiCl2{P(4-MeOC6H4)3}2 (5.0
mol %) with added P(4-MeOC6H4)3 (10 mol %) as a catalyst, the
To date, vinyl chlorides13 have not been successfully utilized
in the carboxylation employing CO2. In the presence of the nickel
catalyst bearing bpy as the ligand, the aliphatic vinyl chlorides (4a
and 4b) afforded the corresponding ,-unsaturated carboxylic
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Scheme 3. Plausible Reaction Mechanism
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catalytic cycle with the aid of the Mn/Et4NI system as an efficient
reducing agent. Further studies on the reaction are now in
progress.
Acknowledgment. This work was supported by Grant-in-Aid
for Scientific Research on Innovative Areas (“Organic synthesis
based on reaction integration” and “Molecular activation directed
toward straightforward synthesis”) from MEXT, Japan, and in
part by the Mitsubishi Foundation.
Supporting Information Available: Experimental procedures and
characterization of the products. This material is available free of
charge via the Internet at http://pubs.acs.org.
References
(1) (a) Carbon Dioxide as Chemical Feedstock; Aresta, M., Ed.;
Wiley-VCH: Weinheim, 2010. (b) Sakakura, T.; Choi, J.-C.;
Yasuda, H. Chem. Rev. 2007, 107, 2365–2387.
acid in high yield (Scheme 1). The vinyl chloride conjugated with
an aryl ring (4c) was also converted to the corresponding
carboxylic acid in moderate yield.
(2) (a) Huang, K.; Sun, C.-L.; Shi, Z.-J. Chem. Soc. Rev. 2011, 40,
2435-2452. (b) Cokoja, M.; Bruckmeier, C.; Rieger, B.; Herrmann,
W. A.; Kühn, F. E. Angew. Chem., Int. Ed. 2011, 50, 8510–8537.
(c) Riduan, S. N.; Zang, Y. Dalton Trans. 2010, 39, 3347–3357.
(d) Aresta, M.; Dibenedetto, A. Dalton Trans. 2007, 2975–2992.
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K. Org. Lett. 2008, 10, 2681–2683.
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6204.
To gain an insight into the catalytic mechanism, we carried
out stoichiometric reactions using NiPhCl(PPh3)2 (6), which was
prepared by the oxidative addition of chlorobenzene to
Ni(PPh3)4.14 In the presence of CO2 (1 atm), Mn powder, Et4NI,
and PPh3 (similar conditions to the catalytic reaction), 6 afforded
the carboxylated product (2p-Me) in 47% yield after
derivatization to the corresponding methyl ester (Scheme 2a).
However, upon the removal of either Mn powder or Et4NI from
the reaction systems, either a trace amount of 2p-Me or no
product was obtained (Scheme 2a). Thus, both Mn and Et4NI
were found to be indispensable for the carboxylation of 6.
Interestingly, a typical homogeneous reducing agent Co(5-
C5H5)2 (Eˊ = – 1.33 V vs. Fc/Fc+ in CH2Cl2)15 can replace the
Mn/Et4NI system to afford 2p-Me in the same yield (Scheme 2b).
Therefore, the Mn/Et4NI system may operate to reduce Ni(II) to
Ni(I). The electrochemical measurements showed that Ni(II)
complexes could be reduced to the corresponding Ni(I) species at
around –0.8 V (vs. SCE in DMF).7c Et4NI could assist the
electron transfer from Mn to the nickel catalyst center via the
bridging of the iodide ion.12b,16 On the other hand, it was reported
that Ni(PPh3)4 reacted with NiCl2(PPh3)2 to provide the Ni(I)
species.17 As shown in Scheme 2c, Ni(PPh3)4 could replace Mn to
afford 2p-Me in 34% yield. These results strongly indicate that
the Ni(I) species18 plays an important role in the present catalytic
carboxylation. Such Ni(I) species were also postulated in the
electrochemical carboxylation.7c
With these observations in Schemes 2, a possible catalytic
cycle for the nickel-catalyzed carboxylation of aryl chlorides with
CO2 is shown in Scheme 3. First, the Ni(II) complex must be
reduced to a Ni(0) species (A). Then, oxidative addition of the
aryl chloride (1) takes place to give a Ni(II) intermediate (B) (step
a). As suggested by the stoichiometric reaction in Scheme 2,
Ni(II) would be reduced by the Mn/Et4NI system to afford Ni(I)
intermediate (C) (step b). The generation of Ni(I) species was
observed in electrochemical reactions.7c Then, the nucleophilic
Ni(I) (C) reacts with CO2 to give the carboxylatonickel
intermediate (D) (step c). Finally, the reduction of D by Mn gives
the corresponding manganese carboxylate and the Ni(0) catalyst
species is regenerated (step d).
(6)
For carboxylation via direct aromatic C-H activation with a directing
moiety or acidic hydrogens, see: (a) Mizuno, H.; Takaya, J.; Iwasawa,
N. J. Am. Chem. Soc. 2011, 133, 1251–1253. (b) Zang, L.; Cheng,
J.; Ohishi, T.; Hou, Z. Angew. Chem., Int. Ed. 2010, 49, 8670–
8673. (c) Boogaerts, I. I. F.; Fortman, G. C.; Furst, M. R. L.; Cazin,
C. S. J.; Nolan, S. P. Angew. Chem., Int. Ed. 2010, 49, 8674–8677.
(d) Boogaerts, I. I. F.; Nolan, S. P. J. Am. Chem. Soc. 2010, 132,
8858–8859.
(7) (a) Troupel, M.; Rollin, Y.; Perichon, J. New J. Chem. 1981, 5,
621–625. (b) Fauvarque, J.-F. ; Chevrot, C.; Jutand, A.; Francois,
M. J. Organomet. Chem. 1984, 264, 273–281. (c) Amatore, C.;
Jutand, A. J. Am. Chem. Soc. 1991, 113, 2819–2825. (d) Torii, S.;
Tanaka, H.; Hamatani, T.; Morisaki, K.; Jutand, A.; Pfluger, F.;
Fauvarque, J.-F. Chem. Lett. 1986, 169–172. (e) Amatore, C.;
Jutand, A.; Khalil, F.; Nielsen, M. F. J. Am. Chem. Soc. 1992, 114,
7076–7085.
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4645–4647.
(9) Correa, A.; Martín, R. J. Am. Chem. Soc. 2009, 131, 15974–15975.
(10) See the Supporting Information for details
(11) When entry 4 was carried out at 60 oC under otherwise identical
conditions, 3a was obtained in 58% yield.12
(12) (a) Zembayashi, M.; Tamao, K.; Yoshida, J.-i.; Kumada, M.
Tetrahedron Lett. 1977, 47, 4089–4092. (b) Iyoda, M.; Otsuka, H.;
Sato, K.; Nisato, N.; Oda, M. Bull. Chem. Soc. Jpn. 1990, 63, 80–
87.
(13) Aryl triflates and vinyl bromides did not afford carboxylated
products at all in the previous Pd-catalyzed carboxylation of aryl
bromides employing CO2.9
(14) (a) Zeller, A.; Herdtweck, E.; Strassner, T. Eur. J. Inorg. Chem.
2003, 1802–1806. (b) Hidai, M.; Kashiwagi, T.; Ikeuchi, T.;
Uchida, Y. J. Organomet. Chem. 1971, 30, 279–282.
(15) Connelly, N. G.; Geiger, W. E. Chem. Rev. 1996, 96, 877–910.
(16) Iyoda, M.; Sakaitani, M.; Otsuka, H.; Oda, M. Chem. Lett. 1985,
127–130.
In conclusion,
a
nickel-catalyzed highly efficient
carboxylation of aryl and vinyl chlorides employing CO2 has been
developed. The present reactions proceeded under a CO2 pressure
of 1 atm at room temperature. The Ni(I) species is involved in the
(17) Heimbach, P. Angew. Chem., Int. Ed. 1964, 3, 648–649.
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