Synthesis of functionalized aryliron complexes [CpFe(CO)2Ar] by copper-mediated transmetalation between [CpFe(CO)2I] and aryltin reagents

Article abstract of DOI:10.1021/om900964e

Transmetalation between [CpFe(CO)₂I] and aryltin reagents in the presence of copper salts yields the corresponding aryliron complexes [CpFe(CO)₂Ar]. The high functional group compatibility of this copper-mediated reaction enables us

Full text of DOI:10.1021/om900964e

Organometallics 2010, 29, 273–274 273
DOI: 10.1021/om900964e
Synthesis of Functionalized Aryliron Complexes [CpFe(CO)2Ar] by
Copper-Mediated Transmetalation between [CpFe(CO)2I] and
Aryltin Reagents
Shigeo Yasuda, Hideki Yorimitsu,* and Koichiro Oshima*
Department of Material Chemistry, Graduate School of Engineering, Kyoto University,
Kyoto-daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
Received November 4, 2009
Summary: Transmetalation between [CpFe(CO)2I] and aryltin
arylzinc, or arylboron reagents.6 Especially, the reactions with
arylzinc or arylboron reagents showed high functional group
compatibility and allowed us to prepare a wide range of [CpFe-
(CO)2Ar]. However, the functional group compatibility of
these methods was not perfect. For example, [CpFe(CO)2Ar]
bearing an acetyl, formyl, or hydroxy group could not be
obtained. Therefore, we turned our attention to transmetala-
tion from other organometallic compounds. Herein we report
that copper salts can promote arylation reactions of [CpFe-
(CO)2I] with aryltin reagents, which show a higher functional
group compatibility than the previous methods.5,6
After extensive screening of the reaction conditions, we
found that copper(I) trifluoromethanesulfonate efficiently
promoted a substitution reaction of [CpFe(CO)2I] (1) with
tributylphenyltin to afford [CpFe(CO)2Ph] (2a) in excellent
yield (Table 1, entry 1). Although dinuclear complex [CpFe-
(CO)2]2 (3) was formed as a byproduct in the reactions with
arylmagnesium,5 arylzinc, or arylboron reagents,6 no formation
of 3 was observed in this copper-mediated reaction. The combi-
nation of CuOTf and a catalytic amount of palladium acetate
lowered the yield of 2a (entry2).7 The amounts of the copper salt
and the tin reagent could be reduced to 1.2 equiv to afford 2a in
slightly lower yield (entry 3). The phenylation reaction did not
proceed efficiently in the presence of a catalytic amount of the
copper salt (entry 4). Copper(II) trifluoromethanesulfonate and
silver(I) trifluoromethanesulfonate showed lower activity
(entries 5 and 6). In entries 4-6, the reactions afforded sig-
nificant amounts of unidentified byproducts other than 1 and
2a. Copper(I) halide showed no activity (entries 7-9).
reagents in the presence of copper salts yields the corresponding
aryliron complexes [CpFe(CO)2Ar]. The high functional group
compatibility of this copper-mediated reaction enables us to
obtain [CpFe(CO)2Ar] having an acetyl or formyl group, which
cannot be prepared by the previous methods with arylzinc or
arylboron reagents under palladium catalysis.
Because of their unique reactivity, organoiron complexes
bearing a dicarbonylcyclopentadienyliron moiety [CpFe-
(CO)2R] have been attracting much attention as useful re-
agents and have found numerous applications in organic
synthesis.1 Among them, the reactivity of the corresponding
aryliron complexes [CpFe(CO)2Ar] has not been fully inves-
tigated2 partly because there are few methods for the synthesis
of [CpFe(CO)2Ar].3 Therefore, the development of efficient
approaches to [CpFe(CO)2Ar] should lead to the progress of
thechemistry of[CpFe(CO)2Ar], which havehigh potential as
useful arylmetal reagents.4
Recently, we have developed an easy and efficient method
for the synthesis of [CpFe(CO)2Ar]: palladium-catalyzed
transmetalation between [CpFe(CO)2I] and arylmagnesium,5
*Corresponding authors. E-mail: yori@orgrxn.mbox.media.kyoto-u.
ac.jp; oshima@orgrxn.mbox.media.kyoto-u.ac.jp.
(1) (a) Pearson, A. J. Iron Compounds in Organic Synthesis; Academic
Press: London, 1994. (b) Pearson, A. J. Pure Appl. Chem. 1983, 55, 1767–
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H.-J. Chem. Rev. 2000, 100, 2941–2961. (e) Knolker, H.-J. Chem. Soc. Rev.
1999, 28, 151–157. (f) R€uck-Braun, K.; Mikulas, M.; Amrhein, P. Synthesis
ꢀ
We assume that phenylcopper species would be generated
from CuOTf and the phenyltin reagents8 and would undergo
transmetalation with 1 to afford 2a.
1999, 727–744. (g) Li, C.-L.; Liu, R.-S. Chem. Rev. 2000, 100, 3127–3161.
(h) Abd-El-Aziz, A. S.; Bernardin, S. Coord. Chem. Rev. 2000, 203, 219–
267. (i) Donaldson, W. A. Curr. Org. Chem. 2000, 4, 837–868. (j)
Nakazawa, H.; Itazaki, M.; Kamata, K.; Ueda, K. Chem. Asian J. 2007, 2,
882–888. (k) Anson, C. E.; Malkov, A. V.; Roe, C.; Sandoe, E. J.; Stephenson,
G. R. Eur. J. Org. Chem. 2008, 196-213, and references therein.
(2) Butler, I. R.; Cullen, W. R.; Lindsell, W. E.; Preston, P. N.; Rettig,
S. J. J. Chem. Soc., Chem. Commun. 1987, 439–441.
(5) Yasuda, S.; Yorimitsu, H.; Oshima, K. Organometallics 2008, 27,
4025–4027.
(6) (a) Asada, Y.; Yasuda, S.; Yorimitsu, H.; Oshima, K. Organome-
tallics 2008, 27, 6050–6052. (b) Yasuda, S.; Asada, Y.; Yorimitsu, H.;
Oshima, K. Materials 2009, 2, 978–991.
(3) The reaction of [CpFe(CO)2I] with phenylmagnesium bromide was
reported to result in a less than 12% yield of [CpFe(CO)2Ph]: (a) Li, H.-J.;
Turnbull, M. M. J. Organomet. Chem. 1991, 419, 245–249. The reaction with
highly reactive aryllithium: (b) Butler, I. R.; Lindsell, W. E.; Preston, P. N.
J. Chem. Res. Synop. 1981, 185. The palladium-catalyzed reactions of aryl
iodides with [CpFe(CO)2]ZnCl, the preparation of which requires NaK2.8: (c)
Artamkina, G. A.; Mil'chenko, A. Y.; Bumagin, N. A.; Beletskaya, I. P.; Reutov,
O. A. Organomet. Chem., USSR 1988, 1, 17–20. The reactions of diarylio-
donium and triarylsulfonium salts with [CpFe(CO)2]Na: (d) Nesmeyanov, A. N.;
Chapovsky, Y. A.; Polovyanyuk, I. V.; Makarova, L. G. J. Organomet. Chem.
1967, 7, 329–337. Decarbonylation of [CpFe(CO)2(ArCO)], which is available
from [CpFe(CO)2]Na and ArCOCl: (e) Hunter, A. D.; Szigety, A. B. Organo-
metallics 1989, 8, 2670-2679, and references therein.
(7) Palladium-catalyzed alkynylation reactions of [CpFe(CO)2I] with
1-alkynylstannanes are known: (a) Lo Sterzo, C. J. Chem. Soc., Dalton
Trans. 1992, 1989–1990. (b) Crescenzi, R.; Lo Sterzo, C. Organometallics
1992, 11, 4301–4305. (c) Ricci, A.; Angelucci, F.; Bassetti, M.; Lo Sterzo, C.
J. Am. Chem. Soc. 2002, 124, 1060-1071, and references therein. (d) Long,
N. J.; Wiliams, C. K. Angew. Chem., Int. Ed. 2003, 42, 2586–2617.
(8) Transmetalation between copper and allylstannanes or alkenyl-
stannanes is known: (a) Wipf, P. Synthesis 1993, 537–557. (b) Farina, V.;
Kapadia, S.; Krishnan, B.; Wang, C.; Liebeskind, L. S. J. Org. Chem. 1994,
59, 5905–5911. (c) Wang, Y.; Burton, D. J. Org. Lett. 2006, 8, 1109–1111.
Copper salts are known to promote the cross-coupling reactions with
arylstannanes. (d) Lam, P. Y. S.; Clark, C. G.; Saubern, S.; Adams, J.; Averill,
K. M.; Chan, D. M. T.; Combs, A. Synlett 2000, 674–676. (e) Mee, S. P. H.;
Lee, V.; Baldwin, J. E. Angew. Chem., Int. Ed. 2004, 43, 1132–1136.
(4) The coordination chemistry of [CpFe(CO)2Ar] has been summarized:
Kerber, R. C. In Comprehensive Organometallic Chemistry II; Abel, E. W.,
Stone, F. G. A., Wilkinson, G., Eds.; Elsevier: Oxford, U.K., 1995; Vol. 7, Chapter 2.
r
2009 American Chemical Society
Published on Web 12/14/2009
pubs.acs.org/Organometallics

274 Organometallics, Vol. 29, No. 1, 2010
Yasuda et al.
Table 2. Copper-Mediated Arylation of 1 with ArSnBu3
Table 1. Optimization of Copper-Mediated Reaction of 1 with
a
PhSnBu3
entry
Ar
2
yield/%
entry
x
additive
y
2a/%
1/%
1
C6H5
2-MeC6H4
4-MeOC6H4
4-FC6H4
3-CF3C6H4
4-NCC6H4
4-MeC(dO)C6H4
4-HC(dO)C6H4
4-HOC6H4
2a
2b
2c
2d
2e
2f
2g
2h
2i
86
68
80
89
92
69
91
84
14
1
2b
3
4
5
6
7
8
9
2.0
2.0
1.2
1.2
1.2
1.2
1.2
1.2
1.2
CuOTf
CuOTf
CuOTf
CuOTf
Cu(OTf)2
AgOTf
CuI
2.0
2.0
1.2
0.10
1.2
1.2
1.2
1.2
1.2
97
77
86
4
27
17
0
0
0
0
9
0
2
3a
4
5
6
7
1
82
84
47
8
CuBr
CuCl
0
0
9b
a 4-MeOC6H4SnMe3 was used. Performed for 5 min. b With 2.0 equiv
of tin reagent and 2.0 equiv of Cu salt. Performed for 20 min.
a Yields were determined by 1H NMR analysis of the crude products.
b With 10 mol % Pd(OAc)2.
trifluoromethanesulfonate was purchased from Aldrich. Aryltin
reagents were prepared according to the literature9 and stored
under argon. [CpFe(CO)2I] was prepared according to the
literature.5 Silica gel (Wakogel 200 mesh) was used for column
chromatography.
The scope of aryltin reagents is summarized in Table 2.
Basically, 1.3 equiv of the copper salt and 1.3 equiv of an
aryltin reagent were used to complete the reactions. The
sterically demanding (2-methylphenyl)tin reagent reacted
with 1 to afford 2b in modest yield (entry 2). The electronic
nature of aryltin reagents had little effect on the yields of
aryliron complexes, and the electron-rich aryliron complex
2c and electron-deficient ones 2d and 2e were obtained in
high yields (entries 3-5). Thanks to the mild reactivity of
organotin reagents, aryliron complexes having a cyano (2f),
acetyl (2g), and formyl (2h) group were readily prepared
(entries 6-8). It is worth noting that aryliron complexes 2g
and 2h could not be prepared from the corresponding
arylzinc or arylboron reagents under palladium catalysis.6
Unfortunately, the reaction of 1 with (4-hydroxyphenyl)tin
reagent failed to afford 2i in reasonable yield (entry 9).
In summary, CuOTf has proven to mediate transmetala-
tion between [CpFe(CO)2I] and aryltin reagents, which
represents an efficient method for the synthesis of various
functionalized aryliron complexes. As notably demonstrated
in the synthesis of 2g and 2h, this method shows a higher
functional group compatibility than the previous reported
palladium-catalyzed arylation reaction with arylzinc or aryl-
boron reagents. The iron complexes would be useful in
various fields of organic chemistry.
Typical Procedure for Copper-Mediated Arylation Reactions
of [CpFe(CO)2I] (Table 2). Dicarbonylcyclopentadienylio-
doiron (1, 152 mg, 0.50 mmol), copper(I) trifluoromethane-
sulfonate/benzene complex (164 mg, 0.65 mmol), tributylphe-
nyltin (239 mg, 0.65 mmol), and 1,4-dioxane (1.7 mL) were
sequentially added in a 30 mL reaction flask under argon. The
mixture was heated to 60 °C and stirred for 1 h. Then the reaction
mixture was cooled to room temperature and filtered through a
pad of silica gel. After evaporation, silica gel column purification
(eluent: CS2) of the crude product provided dicarbonylcyclopen-
tadienylphenyliron (2a, 109 mg, 0.43 mmol, 86% yield).
Characterization Data. The spectral data of the products
2a-2d,5 2e, and 2f6 can be found in the literature.
Dicarbonylcyclopentadienyl(4-acetylphenyl)iron (2g): IR
(Nujol) 2022, 2007, 1943, 1672, 1356, 1275, 1006, 810 cm-1
;
1H NMR (C6D6) δ 2.24 (s, 3H), 3.98 (s, 5H), 7.51 (d, J = 7.5
Hz, 2H), 7.69 (d, J = 7.5 Hz, 2H); 13C NMR (C6D6) δ 26.62,
86.33, 127.10, 134.40, 145.74, 159.77, 197.60, 216.66. Anal.
Found: C, 60.85; H, 4.46. Calcd for C15H12FeO3: C, 60.84; H,
4.08. Mp: 82-84 °C.
Dicarbonylcyclopentadienyl(4-formylphenyl)iron (2h): IR
(Nujol) 2283, 2014, 1964, 1943, 1685, 1573, 1546, 1179,
1
1037, 1008, 834, 813 cm-1; H NMR (C6D6) δ 3.94 (s, 5H),
Experimental Section
7.42 (d, J = 5.5 Hz, 2H), 7.51 (d, J = 5.5 Hz, 2H), 9.84
(s, 1H); 13C NMR (C6D6) δ 86.34, 127.89, 134.19, 146.13,
163.74, 192.40, 216.42. Anal. Found: C, 59.62; H, 3.73.
Calcd for C14H10FeO3: C, 59.61; H, 3.57. Mp: 98-100 °C.
Dicarbonylcyclopentadienyl(4-hydroxyphenyl)iron (2i): IR
(Nujol) 2013, 1942, 1583, 1534, 1365, 1289, 1236, 1187, 1146,
875, 845, 656 cm-1; 1H NMR (CDCl3) δ 4.92 (s, 5H), 6.46 (bs,
1
General Procedures. H NMR (500 and 300 MHz) and 13C
NMR (125.7 and 75.3 MHz) spectra were taken on a Varian
Unity Inova 500 spectrometer and a Varian Gemini 300 spectro-
meter. 1H NMR and 13C NMR spectra were obtained in CDCl3
[using tetramethylsilane (for 1H, δ = 0.00 ppm) and CDCl3 (for
13C, δ = 77.2 ppm) as internal standards] or C6D6 [using C6H6
(for 1H, δ = 7.15 ppm) and C6D6 (for 13C, δ = 128.6 ppm) as
internal standards]. IR spectra were determined on a JASCO IR-
810 spectrometer. Mass spectra (EI) were determined on a JEOL
Mstation 700 spectrometer. The elemental analyses were carried
out at the Elemental Analysis Center of Kyoto University.
Unless otherwise noted, materials obtained from commercial
suppliers were used without further purification. THF was
purchased from Kanto Chemical Co., stored under nitrogen,
and used as is. 1,4-Dioxane was obtained from Wako Pure
Chemicals Co. and stored over slices of sodium. Copper(I)
1H), 6.85 (d, J = 8.0 Hz, 2H), 7.55 (d, J = 8.0 Hz, 2H); 13
C
NMR (CDCl3) δ 86.44, 114.83, 129.64, 143.84, 158.75,
214.28; HRMS (m/z) obsd 269.9977 (Δ = -0.9 ppm), calcd
for C13H10FeO3 269.9979. Mp: 75 °C (dec).
Acknowledgment. This work was supported by
Grants-in-Aid for Scientific Research and for GCOE
Research from MEXT and JSPS. S.Y. acknowledges
JSPS for financial support. H.Y. is thankful for financial
support from The Kurata Memorial Hitachi Science and
Technology Foundation and Mizuho Foundation for the
Promotion of Sciences.
(9) Furuya, T.; Strom, A. E.; Ritter, T. J. Am. Chem. Soc. 2009, 131,
1662–1663.