Air-stable carbonyl(pentamethylcyclopentadienyl)cobalt diiodide complex as a precursor for cationic (pentamethylcyclopentadienyl)cobalt(iii) catalysis: Application for directed C-2 selective C-H amidation of indoles

Article abstract of DOI:10.1002/adsc.201301110

The readily available carbonyl(pentamethylcyclopentadienyl)cobalt diiodide complex [Cp*Co(CO)I₂] was successfully utilized as the precursor of a cationic cobalt(III) active catalyst for directed C-H bond functionalization. The complex Cp*Co(CO)I₂ (2.5-1.25 mol%), in combination with silver hexafluoroantimonate (AgSbF₆) and potassium acetate (KOAc), efficiently catalyzed the directed C-2 selective amidation of indoles with sulfonyl azides, and the corresponding products were obtained in 85-98 % yield.

Full text of DOI:10.1002/adsc.201301110

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DOI: 10.1002/adsc.201301110
Air-Stable Carbonyl(pentamethylcyclopentadienyl)cobalt
Diiodide Complex as a Precursor for Cationic
(Pentamethylcyclopentadienyl)cobalt
(III) Catalysis: Application
À
Bo Sun,a Tatsuhiko Yoshino,a Shigeki Matsunaga,a,b,* and Motomu Kanaia,*
a
Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
Fax : (+81)-3-5684-5206; phone: (+81)-3-5841-4830; e-mail: kanai@mol.f.u-tokyo.ac.jp
ACT-C, JST, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
b
Fax : (+81)-3-5684-5206; phone: (+81)-3-5841-4836; e-mail: smatsuna@mol.f.u-tokyo.ac.jp
Received: December 9, 2013; Published online: && &&, 0000
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201301110.
Abstract: The readily available carbonyl(pentame-
thylcyclopentadienyl)cobalt diiodide complex
[Cp*Co(CO)I2] was successfully utilized as the pre-
ported the utility of a cationic [Cp*Co
(PF6)2 complex for the addition of 2-phenylpyridine-
s[4a] and indoles[4b] to imines. Here, we describe our ef-
forts to expand the scope of Cp*Co(III) catalysis. A
readily available Cp*Co(CO)I2 complex was success-
fully utilized as the precursor of a cationic Co(III)
ACHUTNGTREN(NUG III)ACHTUNGTRENNUNG(C6H6)]
AHCTUNGTRENNUNG
cursor of a cationic cobalt
(III) active catalyst for di-
ACHTUNGTRENNUNG
À
rected C H bond functionalization. The complex
Cp*Co(CO)I2 (2.5–1.25 mol%), in combination
with silver hexafluoroantimonate (AgSbF6) and po-
tassium acetate (KOAc), efficiently catalyzed the
directed C-2 selective amidation of indoles with sul-
fonyl azides, and the corresponding products were
obtained in 85–98% yield.
ACHTUNGTRENNUNG
active catalyst in a directed C-2 selective amidation of
indoles.
Chang and co-workers recently reported on
À
Cp*Rh
G
tions using sulfonyl, aryl, and alkyl azides as amino
sources.[7–12] The reactions using a variety of substrates
proceeded smoothly in good yield, releasing N2 gas as
a sole by-product.[9–11] These results led us to evaluate
À
À
Keywords: catalysis; C H functionalization; C N
bond formation; cobalt; indoles
the catalytic activity of a cationic [Cp*Co
(PF6)2 complex for the same reaction. The reactivity
of the [Cp*Co(III)(C6H6)](PF6)2 complex in the reac-
tion of indole 1a with azide 2a, however, was poor,
ACHUTNGTREN(NUG III)ACHTUNGTRENNUNG(C6H6)]
AHCTUNGTRENNUNG
N
G
ACHTUNGTRENNUNG
À
Transition metal-catalyzed directed C H bond func- giving product 3aa in only 4% yield in the presence of
tionalization has emerged as a powerful synthetic KOAc (Table 1, entry 1).[13] Thus, we investigated the
methodology[1] that is potentially superior to tradi- reaction in more detail to identify a suitable cobalt-
tional organic reactions using stoichiometric amounts based catalyst. We assumed that the inferior activity
of activating reagents. Among the various transition of the [Cp*Co
metal catalysts suitable for directed C H bond func- due to the thermal instability of the PF6 ion under
(III)
E
E
À
tionalization, Cp*Rh
G
lished role.[2] Cationic Cp*Rh
widely utilized for various C C, C N, and many complex were not successful due to problems in the
À
other C X bond formation processes. Despite their purification step. As an alternative method to gener-
utility in C H functionalization, however, the need ate catalytically active cationic Cp*Co
À
for expensive and precious rhodium sources is eco- situ, we determined that a Cp*Co(CO)I2 complex in
nomically and environmentally disadvantageous, espe- combination with a suitable Ag salt was effective.
cially for future industrial applications. Therefore, the Among the Ag salts screened (entries 2–4), AgSbF6
development of an inexpensive base metal catalyst as was best, and 2.5 mol% of Cp*Co(CO)I2 with 5 mol%
an alternative to cationic Cp*Rh
highly desired. As part of our ongoing studies on Cp*Co
first-row transition metal catalysis,[3–6] we recently re- lower reactivity than that generated with other Ag
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
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Bo Sun et al.
Table 1. Optimization studies.
Entry
Co salt [mol%]
[Cp*Co(III)(C6H6)]
Cp*Co(CO)I2 (2.5)
Cp*Co(CO)I2 (2.5)
Cp*Co(CO)I2 (2.5)
Cp*Co(CO)I2 (2.5)
Cp*Co(CO)I2 (2.5)
Cp*Co(CO)I2 (2.5)
Ag salt [mol%]
KOAc [mol%]
Yield [%][b]
1
2
3
4
5
6
7
G
G
E
(PF6)2 (5)
none
10
5
5
5
0
4
AgPF6 (5)
AgNTf2 (5)
AgSbF6 (5)
AgOAc (5)
AgSbF6 (5)
none
14
79
81
trace
33
0
0
5
8
9
10
11
12
13[c]
Co
(acac)3 (5)
none
none
none
AgSbF6 (10)
AgSbF6 (10)
AgSbF6 (5)
10
10
10
10
10
5
0
0
0
0
Co(NH3)6Cl3(5)
E
Co2(CO)8 (2.5)
CoI2 (5)
C
66
92[d]
[a]
The reaction was run using 1a (0.20 mmol) and 2a (0.30 mmol) in 1,2-dichloroethane (0.3M) at 1008C, unless otherwise
noted.
[b]
[c]
[d]
1
Yield of 3aa determined by H NMR analysis of the crude mixture using an internal standard.
The reaction was run using 1a (0.30 mmol) and 2a (0.20 mmol).
Isolated yield of 3aa based on 2a after purification by silica gel column chromatography.
salts (entry 2 vs. entries 3 and 4), supporting our as- drawing substituents on indoles were compatible, and
À
sumption that the PF6 ion was not appropriate. Trials various 4-, 5-, or 6-substituted indoles showed good
to generate an efficient catalyst with AgOAc in the reactivity (entries 2–9, 85–92% yield). Not only other
absence of KOAc failed, resulting in poor reactivity arylsulfonyl azides 2b–2e, but also alkylsulfonyl azides
(entry 5). The reaction in the absence of either KOAc 2f–2g reacted smoothly under Cp*CoACTHUNTGRNEUNG(III) catalysis,
or AgSbF6 also gave a low yield (entry 6: 33%, and the products were obtained in 86–98% yield (en-
entry 7: 0%), indicating that both AgSbF6 and KOAc tries 10–15). The reaction proceeded nicely with a re-
were essential to generate the catalytically active spe- duced catalyst loading (entry 16: 1.25 mol%), and
cies in situ. Commercially available Co
as Co(acac)3 and [Co(NH3)6Cl3] did not promote the (TON=68).
reaction (entries 8 and 9). No reaction occurred when A plausible catalytic cycle of the reaction is shown
ACHTUNGTREN(NUNG III) salts such a good catalyst turnover number was observed
A
ACHTUNGTRENNUNG
using other Co catalysts, such as Co2(CO)8 or CoI2 in Figure 1. As an initiation step, halogen abstraction
with AgSbF6 (entries 10 and 11). A [Cp*CoCl2]2 com- from Cp*Co(CO)I2 with AgSbF6, dissociation of CO,
plex[15] with AgSbF6 promoted the reaction, but and ligand exchange to acetate (or substrate) gener-
the reactivity was slightly lower than that with ates the postulated active species I. After coordina-
Cp*Co(CO)I2 (entry 12, 66% yield), confirming that tion of the pyrimidyl group of indole 1 (II), regiose-
À
À
the cationic Cp*CoACTHNUTRGNE(UNG III) species is essential for C H lective C H metalation occurs at the C-2 position via
bond activation. Finally, performing the reaction with either SEAr or a concerted metalation-deprotonation
1.5 equiv. of 1a led to the best yield of 3aa (92% iso- mechanism[17] to afford cobaltacyclic complex III. Co-
lated yield based on 2, entry 13). The utility of the ordination of azide 2 to cobalt (IV) and further mi-
Cp*Co(CO)I2 complex as a precursor for generating
a cationic Cp*CoACTHNUTRGNEUNG(III) catalytically active species is
noteworthy, because the Cp*Co(CO)I2 complex was
air-stable, and readily available in just one-pot (two
steps) from commercially available pentamethylcyclo-
pentadiene and Co2(CO)8 with 86% yield on a >10
gram scale (Scheme 1).[16]
The substrate scope of the reaction is summarized
in Table 2. Both electron-donating and electron-with- Scheme 1. Preparation of Cp*Co(CO)I2 complex.
2
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Air-Stable Carbonyl(pentamethylcyclopentadienyl)cobalt Diiodide
Table 2. Cobalt-catalyzed C-2 selective amidation of indoles.[a]
Entry
X, 1
R, 2
x
3
Yield [%][b]
1
2
3
4
5
6
7
8
H, 1a
4-Me-C6H4, 2a
4-Me-C6H4, 2a
4-Me-C6H4, 2a
4-Me-C6H4, 2a
4-Me-C6H4, 2a
4-Me-C6H4, 2a
4-Me-C6H4, 2a
4-Me-C6H4, 2a
4-Me-C6H4, 2a
C6H5, 2b
4-MeO-C6H4, 2c
4-CF3-C6H4, 2d
4-Cl-C6H4, 2e
Bn, 2f
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
1.25
3aa
3ba
3ca
3da
3ea
3fa
3ga
3ha
3ia
3ab
3ac
3ad
3ae
3af
92
92
92
85
89
89
89
90
88
98
87
87
88
97
86
86
5-Me, 1b
6-Me, 1c
5-MeO, 1d
5-CO2Me, 1e
5-F, 1f
5-Cl, 1g
5-Br, 1h
4-Br, 1i
H, 1a
H, 1a
H, 1a
H, 1a
H, 1a
9
10
11
12
13
14
15
16[c]
H, 1a
H, 1a
Bu, 2g
4-Me-C6H4, 2a
3ag
3aa
[a]
The reaction was run using 1 (0.30 mmol) and 2 (0.20 mmol) in 1,2-dichloroethane (0.3M) at 1008C, unless otherwise
noted.
Isolated yield of 3 (based on 2) after purification by silica gel column chromatography.
The reaction was run in 1,2-dichloroethane (0.5M) for 22 h.
[b]
[c]
gratory insertion generate Co
G
In summary, we have demonstrated the utility of
with the release of N2. Protonation of V with AcOH a readily available Cp*Co(CO)I2 complex as the pre-
then gives product 3 and regenerates active species I. cursor for cationic Cp*Co
N
À
lective directed C H amidation of indoles was effi-
ciently promoted by the in-situ generated Cp*Co
catalysis, while a preformed [Cp*CoCAHTUNGRTEN(UNNG III)AHCTUNTGNREN(UG C6H6)]ACHTUNGTRENNUNG
complex was not effective. A Cp*Co(CO)I2/AgSbF6/
KOAc combined system gave products in 85–98%
yield, and catalyst loading was successfully reduced to
1.25 mol% (TON up to 68, based on Co). Further
studies to expand the scope of the Cp*Co
sis are actively ongoing in our group.
ACHTUNGTREN(NUNG III) cataly-
Experimental Section
Catalyst Preparation (Scheme 1)
To a well-dried 2-necked 500-mL flask were successively
added Co2(CO)8 (5.0 g, 14.6 mmol), degassed CH2Cl2
(100 mL), and pentamethylcyclopentadiene (5.55 mL,
35.4 mmol). The mixture was refluxed under an argon
stream for 6 h and then cooled to room temperature. The
solvent was removed under vacuum. The residue was dis-
solved in degassed Et2O (50 mL), and then iodine (9.0 g,
35.5 mmol) in degassed Et2O (50 mL) was added dropwisely
at room temperature with stirring. [Caution: During the ad-
Figure 1. Postulated catalytic cycle.
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dition, the mixture refluxed due to the exothermic reaction
and CO gas evolution was observed.] After the mixture had
been stirred at room temperature for 1 h, the solvent was
evaporated. The resulting residue was purified by silica gel
column chromatography (hexane then CH2Cl2/hexane=4/1)
to afford a deep purple crystalline solid; yield: 12.0 g (86%).
[3] Review on the first-row transition metal-catalyzed C
À
H bond activation/C C bond formation, a) A. A. Kul-
karni, O. Daugulis, Synthesis 2009, 4087; b) N. Yoshikai,
Synlett 2011, 1047.
[4] Synthetic utility of the [Cp*CoACHTUNGTRENN(NGU III)AHCTUNEGTRGNN(NU C6H6)]ACHTUNGTERN(NUGN PF6)2 com-
plex: a) T. Yoshino, H. Ikemoto, S. Matsunaga, M.
Kanai, Angew. Chem. 2013, 125, 2263; Angew. Chem.
Int. Ed. 2013, 52, 2207; b) T. Yoshino, H. Ikemoto, S.
Matsunaga, M. Kanai, Chem. Eur. J. 2013, 19, 9142.
[5] Low-valent cobalt catalysts have been intensively inves-
À
General Procedure for Directed C H Amidation
(Table 2)
To
a
dried screw-capped vial were added indole
À
tigated for C H functionalization reactions. For leading
1 (0.30 mmol), azide 2 (0.20 mmol), Cp*Co(CO)I2 (2.4 mg, 5
mmol), AgSbF6 (3.4 mg, 10 mmol), KOAc (1.0 mg, 10 mmol),
and 1,2-dichloroethane (0.60 mL) under an argon atmos-
phere. The vial was capped, and the mixture was heated at
1008C for 12 h with stirring. The resulting mixture was
cooled to room temperature, and directly purified by silica
gel column chromatography to give product 3.
examples, see: a) K. Gao, P.-S. Lee, T. Fujita, N. Yoshi-
kai, J. Am. Chem. Soc. 2010, 132, 12249; b) K. Gao, N.
Yoshikai, J. Am. Chem. Soc. 2011, 133, 400; c) Q.
Chen, L. Ilies, E. Nakamura, J. Am. Chem. Soc. 2011,
133, 428; d) B. Li, Z.-H. Wu, Y.-F. Gu, C.-L. Sun, B.-Q.
Wang, Z.-J. Shi, Angew. Chem. 2011, 123, 1141; Angew.
Chem. Int. Ed. 2011, 50, 1109; e) Z. Ding, N. Yoshikai,
Angew. Chem. 2012, 124, 4776; Angew. Chem. Int. Ed.
2012, 51, 4698; f) W. Song, L. Ackermann, Angew.
Chem. 2012, 124, 8376; Angew. Chem. Int. Ed. 2012, 51,
8251.
Acknowledgements
[6] For selected recent examples from our group on first-
row transition metal catalysis: a) T. Andou, Y. Saga, H.
Komai, S. Matsunaga, M. Kanai, Angew. Chem. 2013,
125, 3295; Angew. Chem. Int. Ed. 2013, 52, 3213; b) S.
Kato, M. Kanai, S. Matsunaga, Chem. Asian J. 2013, 8,
1768; c) N. Takemura, Y. Kuninobu, M. Kanai, Org.
Lett. 2013, 15, 844; d) N. Takasu, K. Oisaki, M. Kanai,
Org. Lett. 2013, 15, 1918; e) K. Kaneko, T. Yoshino, S.
Matsunaga, M. Kanai, Org. Lett. 2013, 15, 2502.
This work was supported in part by ACT-C from JST, and
Grant-in-Aid for Scientific Research on Innovative Areas
“Molecular Activation Directed toward Straightforward Syn-
thesis” from MEXT. B.S. is thankful for the Japanese Gov-
ernment Fellowship and T.Y. is thankful for a JSPS fellow-
ship.
[7] Reviews on transition metal-catalyzed N-atom transfer
reactions of azides: a) T. Katsuki, Chem. Lett. 2005, 34,
1304; b) T. G. Driver, Org. Biomol. Chem. 2010, 8,
3831; c) S. H. Kim, S. H. Park, J. H. Choi, S. Chang,
Chem. Asian J. 2011, 6, 2618.
References
À
À
[1] Recent reviews on C H bond functionalization: a) C
H Activation, in: Topics in Current Chemistry, Col. 292,
(Eds.: J.-Q. Yu, Z.-J. Shi), Springer, Heidelberg, Berlin,
2010; b) D. A. Colby, R. G. Bergman, J. A. Ellman,
Chem. Rev. 2010, 110, 624; c) I. A. I. Mkhalid, J. H.
Barnard, T. B. Marder, J. M. Murphy, J. F. Hartwig,
Chem. Rev. 2010, 110, 890; d) T. W. Lyons, M. S. San-
ford, Chem. Rev. 2010, 110, 1147; e) J. Wencel-Delord,
T. Drçge, F. Liu, F. Glorius, Chem. Soc. Rev. 2011, 40,
4740; f) S. H. Cho, J. Y. Kim, J. Kwak, S. Chang, Chem.
Soc. Rev. 2011, 40, 5068; g) L. Ackermann, Chem. Rev.
2011, 111, 1315; h) C. Zhu, R. Wang, J. R. Falck, Chem.
Asian J. 2012, 7, 1502; i) N. Kuhl, M. N. Hopkinson, J.
Wencel-Delord, F. Glorius, Angew. Chem. 2012, 124,
10382; Angew. Chem. Int. Ed. 2012, 51, 10236; j) K. M.
Engle, T.-S. Mei, M. Wasa, J.-Q. Yu, Acc. Chem. Res.
2012, 45, 788; k) J. Yamaguchi, A. D. Yamaguchi, K.
Itami, Angew. Chem. 2012, 124, 9092; Angew. Chem.
Int. Ed. 2012, 51, 8960; l) B.-J. Li, Z.-J. Shi, Chem. Rev.
2012, 112, 5879; m) P. B. Arockiam, C. Bruneau, P. H.
Dixneuf, Chem. Rev. 2012, 112, 5879; n) J. Wencel-
Delord, F. Glorius, Nature Chem. 2013, 5, 369; o) G.
Rouquet, N. Chatani, Angew. Chem. 2013, 125, 11942;
Angew. Chem. Int. Ed. 2013, 52, 11726.
À
[8] Reviews on transition metal-catalyzed C H amination/
amidation based on different strategies: a) J. Du Bois,
Org. Process Res. Dev. 2011, 15, 758; b) A. Armstrong,
J. C. Collins, Angew. Chem. 2010, 122, 2332; Angew.
Chem. Int. Ed. 2010, 49, 2282; c) F. Collet, R. H. Dodd,
P. Dauban, Chem. Commun. 2009, 5061; d) H. M. L.
Davies, J. R. Manning, Nature 2008, 451, 417; e) A. R.
Dick, M. S. Sanford, Tetrahedron 2006, 62, 2439;
f) H. M. L. Davies, M. S. Long, Angew. Chem. 2005,
117, 3584; Angew. Chem. Int. Ed. 2005, 44, 3518; g) P.
Mꢁller, C. Fruit, Chem. Rev. 2003, 103, 2905.
[9] a) J. Y. Kim, S. H. Park, J. Ryu, S. H. Cho, S. H. Kim, S.
Chang, J. Am. Chem. Soc. 2012, 134, 9110; b) J. Ryu,
K. Shin, S. H. Park, J. Y. Kim, S. Chang, Angew. Chem.
2012, 124, 10042; Angew. Chem. Int. Ed. 2012, 51, 9904;
c) K. Shin, Y. Baek, S. Chang, Angew. Chem. 2013, 125,
8189; Angew. Chem. Int. Ed. 2013, 52, 8031.
[10] Cp*RhACTHNUTRGNEUG(N III)-catalyzed N-atom transfer reactions with
azides from other groups, a) J. Shi, B. Zhou, Y. Yang,
Y. Li, Org. Biomol. Chem. 2012, 10, 8953; b) D.-G. Yu,
M. Suri, F. Glorius, J. Am. Chem. Soc. 2013, 135, 8802;
c) Y. Lian, J. R. Hummel, R. G. Bergman, J. A. Ellman,
J. Am. Chem. Soc. 2013, 135, 12548.
[2] Reviews on Cp*RhACTHUNGTRENNG(U III) catalysis: a) T. Satoh, M.
Miura, Chem. Eur. J. 2010, 16, 11212; b) F. W. Patureau,
J. Wencel-Delord, F. Glorius, Aldrichimica Acta 2012,
45, 31; c) G. Song, F. Wang, X. Li, Chem. Soc. Rev.
2012, 41, 3651; d) S. Chiba, Chem. Lett. 2012, 41, 1554.
À
[11] For related C H amination/amidation reactions with
acyl, sulfonyl, and aryl azides under Ir and Ru catalysis,
a) J. Ryu, J. Kwak, K. Shin, D. Lee, S. Chang, J. Am.
4
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COMMUNICATIONS
Air-Stable Carbonyl(pentamethylcyclopentadienyl)cobalt Diiodide
Chem. Soc. 2013, 135, 12861; b) D. Lee, Y. Kim, S.
Chang, J. Org. Chem. 2013, 78, 11102; c) J. Kim, J.
Kim, S. Chang, Chem. Eur. J. 2013, 19, 7328; d) M. R.
Yadav, R. K. Rit, A. K. Sahoo, Org. Lett. 2013, 15,
1638; e) M. Bhanuchandra, M. R. Yadav, R. K. Rit,
M. R. Kuram, A. K. Sahoo, Chem. Commun. 2013, 49,
5225; f) Q.-Z. Zheng, Y.-F. Liang, C. Qin, N. Jiao,
Chem. Commun. 2013, 49, 5654.
directing group, see: L. Ackermann, A. V. Lygin, Org.
Lett. 2011, 13, 3332.
[14] The stablity of the PF6 ion in Cp*Co
À
A
N
complexes dependedÀ on ligands. For example, rapid
solvolysis of the PF6 ion in a [Cp*Co(III)(acetone)3]
(PF6)2 complex was reported, see: G. Fairhurst, C.
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
White, J. Chem. Soc. Dalton. Trans. 1979, 1524.
[15] The [Cp*CoCl2]2 complex was used as a crude material,
possibly contaminated with oligomeric Co(II) and Co-
À
[12] Other C H amination/amidation reactions under
Cp*Rh
N
AHCTUNGTREGUN(NN III) species. Trials to obtain analytically pure
Yu, Org. Lett. 2012, 14, 272; b) C. Grohmann, H.
Wang, F. Glorius, Org. Lett. 2012, 14, 656; c) R.-J. Tang,
C.-P. Luo, L. Yang, C.-J. Li, Adv. Synth. Catal. 2013,
355, 869; d) C. Grohmann, H. Wang, F. Glorius, Org.
Lett. 2013, 15, 3014; e) H. Zhao, Y. Shang, W. Su, Org.
Lett. 2013, 15, 5106.
[Cp*CoCl2]2 failed.
[16] The procedure in Scheme 1 was performed with slight
modification of reported methods: see, a) S. A. Frith, J.
Spencer, in: Inorganic Syntheses: Reagents for Transi-
tion Metal Complex and Organometallic Syntheses, Vol.
28, (Ed.: R. J. Angelici), Inorganic Syntheses, Inc.,
pp 273–277; b) W. Li, L. Weng, G. Jin, Inorg. Chem.
Commun. 2004, 7, 1174.
[17] Review on concerted metalation-deprotonation mecha-
nism: D. Lapointe, K. Fagnou, Chem. Lett. 2010, 39,
1118.
[13] Cp*CoACHTUNGTRENNUNG(III)ACHTUNGTRENNUNG(C6H6)]ACTHNGUTREN(NGUN PF6)2/KOAc were the optimized
conditions for C-2 selective indole addition to imines,
see, ref.[4b] In this study, we used only indoles bearing
a pyrimidyl directing group. Full scope of substrates in-
cluding directing group effects will be reported in due
course as a full article. For the utility of the pyrimidyl
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6 Air-Stable Carbonyl(pentamethylcyclopentadienyl)cobalt
Diiodide Complex as a Precursor for Cationic
(Pentamethylcyclopentadienyl)cobaltACTHNUGRTENUNG(III) Catalysis:
À
Application for Directed C-2 Selective C H Amidation of
Indoles
Adv. Synth. Catal. 2014, 356, 1 – 6
Bo Sun, Tatsuhiko Yoshino, Shigeki Matsunaga,*
Motomu Kanai*
6
asc.wiley-vch.de
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 0000, 000, 0 – 0
ÝÝ
These are not the final page numbers!