Quadri-synergetic effect for highly effective carbon dioxide fixation and its application to indoloquinolinone

Article abstract of DOI:10.1002/adsc.201200469

The first copper-catalyzed cyclic anti-nucleometallation-carboxylation of 2-alkynylanilines with carbon dioxide in the presence of dimethylzinc (ZnMe ₂) and cesium fluoride (CsF) for the effective synthesis of indolyl-3-carboxylic acids and indolodihydropyran-2-one is described. Through a mechanistic study, it is unveiled that the metal ions Cu²⁺, Zn ²⁺, Cs⁺ and F^- are working together for this CO₂-based highly efficient carboxylation. Copyright

Full text of DOI:10.1002/adsc.201200469

COMMUNICATIONS
DOI: 10.1002/adsc.201200469
Quadri-Synergetic Effect for Highly Effective Carbon Dioxide
Fixation and Its Application to Indoloquinolinone
Suhua Lia and Shengming Maa,b,*
a
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of
Sciences, 345 Lingling Lu, Shanghai 200032, Peopleꢀs Republic of China
Fax : (+86)-21-6260-9305; e-mail: masm@sioc.ac.cn
Shanghai Key Laboratory of Green Chemistry and Chemical Process, Department of Chemistry, East China Normal
b
University, 3663 North Zhongshan Lu, Shanghai 200062, Peopleꢀs Republic of China
Received: May 28, 2012; Published online: && &&, 0000
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201200469.
Abstract: The first copper-catalyzed cyclic anti-nu-
cleometallation–carboxylation of 2-alkynylanilines
with carbon dioxide in the presence of dimethylzinc
(ZnMe2) and cesium fluoride (CsF) for the effective
synthesis of indolyl-3-carboxylic acids and indolodi-
hydropyran-2-one is described. Through a mechanis-
tic study, it is unveiled that the metal ions Cu2+,
Zn2+, Cs+ and Fꢀ are working together for this CO2-
based highly efficient carboxylation.
Keywords: alkynes; carbon dioxide; carboxylation;
copper; nucleometalation
Scheme 1. Carboxylation reactions with CO2.
It is well known that the aza-metallation of o-(1-al-
kynyl)anilines would afford indoles.[18–21] By taking
Much attention has been paid to the reactivity of CO2 the intermediate B formed from the cyclic anti-aza-
recently for the sake of environmental reasons and its metallation of alkynes as the starting point, its reac-
abundant, inexpensive, and non-toxic features as a C1 tion with CO2 under the reported protocols for the
synthon.[1] Challenges are its thermodynamic and ki- indole synthesis from 2-alkynylanilines was attempted
netic stability. With more than ten years endeavor, (Table 1, entries 1–4).[18–21] Unfortunately, no indole-
there are mainly two types of transition metal-cata- carboxylic acid 2a was formed indicating the low reac-
lyzed carboxylation reactions by using CO2 to form tivity of intermediate C (M=Rh, Hg) towards CO2.
new carbon-carbon bonds: (i) the carboxylation of It is surprising that no carboxylation occurred even
less reactive organometallic reagents (Sn,[2] B,[3] with Cu
(OAc)2
although the are many reports
[21]
Zn[4,5]), aryl bromides,[6] arenes,[7] and terminal C H on
Cu-catalyzed
CO2-based
carboxylation
ꢀ
bonds of alkynes[8] affording carboxylic acids reaction![3b–e,7b,c,8a,b,d,10c]
[Scheme 1, Eq. (1)] and (ii) the carboxylation of
Thus, we started to identify such an intermediate C,
carbon-carbon multiple bonds of alkenes,[9] alkynes,[10] which would have a much higher reactivity towards
and allenes[11] [Scheme 1, Eq. (2)].[12,13] On the other CO2. Recently, there are some reports on the carbox-
hand, anti-nucleometallation of carbon-carbon multi- ylation of zinc reagents with CO2 producing related
ple bond is a key transformation in many transition carboxylic acids under the catalysis of nickel or palla-
metal-mediated syntheses.[14,15] However, there is no dium or promoted by LiCl.[4,5] Interestingly, when 1a
report on reactions of this type involving in situ gener- was reacted with 3 equivalents of ZnEt2 in DMF
ated vinylic metallic intermediates with carbon diox- under the atmosphere of CO2 for 24 h, the expected
ide.[16] Here, we would like to report the first example product 2a was indeed formed albeit in only 8% yield
on such a concept for the synthesis of indolecarboxyl- together with 65% of the aza-metallation-protonolysis
ic acid derivatives.[17]
product 3a. The reaction was slightly improved by
adding 1.5 equivalents of CsF. In the presence of
Adv. Synth. Catal. 0000, 000, 0 – 0
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1
ÞÞ
These are not the final page numbers!

Suhua Li and Shengming Ma
COMMUNICATIONS
Table 1. Attempted reactions of intermediate C with CO2.
Entry
Catalyst
Solvent
Temperature [oC]
NMR yield [%]
Ref.
2a
3a
[18]
[19]
[20]
[21]
1[a,b]
2[c,d]
3[d]
–
Rh
Hg
Cu(OAc)2
toluene
toluene
CH2Cl2
DCE
reflux
100
rt
0
0
0
0
53
92
100
99
[e]
(OTf)2 [f]
4[b]
U
reflux
[a]
1.2 equiv. of ZnEt2 were used.
The reaction time was 24 h.
5 mol% of Rh(CO)2acac and 5.5 mol% of rac-BINAP were used. Toluene/H2O=10/1.
The reaction time was 17 h.
5 mol%.
20 mol%.
[b]
[c]
[d]
[e]
[f]
Scheme 2. Effect of zinc reagent.
5 mol% of Cu
G
Next, the scope of the reaction was studied under
lar results. Surprisingly, the selectivity of 2a vs. 3a was the standard conditions (Table 3). Various substituted
dramatically improved when ZnMe2 was used instead groups R1 at the terminal position of the alkynes
of ZnEt2 (Scheme 2)!
moiety such as aryl (entries 1 and 2), thienyl (entry 3),
Such a reaction in DMSO, THF, or MeCN afforded alkenyl (entry 4), benzyl (entry 5), and alkyl (en-
the carboxylation product 2a in 75–79% yield togeth- tries 6–10) were tested producing excellent yields of
er with 5–20% of cycloisomerization product 3a (en- the corresponding indole-3-carboxylic acids. When R2
tries 1–3, Table 2). Other copper salts, such as is the electron-donating methoxy group, carboxylic
CuACHTUNGTRENNUNG(OTf)2, CuI, CuBr, CuCl, were tested and no acid 2q could also be produced in 92% yield
better result was observed (entries 4–7). Reducing the (entry 15). 2-Alkynylanilines with a ketonic carbonyl
amount of ZnMe2, CsF and catalyst loading resulted group in R1 (entry 6), halogen (entries 11, 12, and 14)
in diminished yields (entries 8–10). Other protecting and ester (entry 13) functionality in R2 or R3 of the
groups were also been examined: when Boc was used, aryl group could also work very well in this reaction,
44% of carboxylic acid was produced. The substrates leaving further opportunity for elaboration without
with an Ac or a trifluoroacetyl group produced a com- protection and deprotection. The reaction can be con-
plicated mixture.
ducted using 3 mmol (1.1 g) of 1h to produce 2h in
2
asc.wiley-vch.de
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 0000, 000, 0 – 0
ÝÝ
These are not the final page numbers!

Quadri-Synergetic Effect for Highly Effective Carbon Dioxide Fixation
Table 2. Optimization of reaction conditions.[a]
Entry
Cat.
Cu(OAc)2
Solvent
Yield [%] of 2a[b]
Yield [%] of 3a[b]
1
2
3
4
5
6
7
G
DMSO
THF
79
78
75
83
85
79
83
76
83
82
5
9
Cu
Cu
U
CH3CN
DMF
DMF
DMF
DMF
DMF
DMF
DMF
20
13
11
16
14
5
CuACHTUNTGRENNUNG
CuI
CuBr
CuCl
8[c]
9[d]
10[e]
Cu
Cu
Cu
ACHTUNGTRENNUNG
A
AHCTUNGTRENNUNG
12
8
[a]
The reaction was carried out with 0.5 mmol of 1a, Cu (5 mol%), CsF (1.5 equiv.), ZnMe2 (1.2M in toluene, 1.25 mL,
1.5 mmol), and a balloon of CO2 (about 1 L) in 3 mL of the indicated solvent at the indicated temperature.
NMR yield.
2 equiv. of ZnMe2 were used instead of 3 equiv. of ZnMe2.
1 equiv. of CsF was used.
3 mol% of CuACHTUNGTRENNUNG(OAc)2 were used.
[b]
[c]
[d]
[e]
Table 3. Synthesis of indolyl-3-carboxylic acid from 2-alkynylanilines.[a]
Entry
2-Alkynylaniline 1
Yield [%] of 2[b]
R1
R2
R3
1
2
3
4
5
6
7
8
Ph
H
H
H
H
H
H
H
H
H
H
F
Cl
CO2Me
Cl
OMe
H (1a)
H (1b)
H (1c)
H (1d)
H (1e)
H (1f)
H (1g)
H (1h)
H (1h)
H (1i)
H (1j)
H (1k)
H (1l)
F (1m)
H (1q)
94 (2a)
90 (2b)
91 (2c)
96 (2d)
94 (2e)
87 (2f)
92 (2g)
90 (2h)
86 (2h)
94 (2i)
93 (2j)
97 (2k)
92 (2l)
95 (2m)
92 (2q)
p-MeOC6H4
2-thienyl
1-cyclohexenyl
Bn
CH2CH2Ac
n-Bu
CH2OBn
CH2OBn
CH2Cy
n-Bu
9[c]
10
11
12
13
14
15
n-Bu
n-Bu
n-Bu
n-Bu
[a]
The reaction was carried out with 0.5 mmol of 1, CuACHTNUTRGNE(UNG OAc)2 (5 mol%), CsF (1.5 equiv.), ZnMe2 (1.2M in toluene,
1.25 mL), and a balloon of CO2 (about 1 L) in 3 mL of DMF at 558C.
Isolated yield.
The reaction was conducted using 3.0 mmol (1.174 g) of 1 h.
[b]
[c]
86% yield (entry 9), which showed the practicality of
this reaction. The structure of 2d was confirmed by its tural subunits in a large number of natural com-
X-ray diffraction study (Figure 1, left).[22] pounds showing important biological activities.[23]
Six-membered lactones are widely present as struc-
Adv. Synth. Catal. 0000, 000, 0 – 0
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
3
ÞÞ
These are not the final page numbers!

Suhua Li and Shengming Ma
COMMUNICATIONS
Figure 1. ORTEP plot of 2d (left) and 4o (right) shown with ellipsoids at the 30% probability level.
From the structure of 2, we envisioned that if there is
After addition of two equivalents of ZnMe2 (1.2M
a hydroxy group in R1, lactones may be formed after in toluene) to the solution of 1a in DMF-d7 at room
anti-amino carboxylation followed by lactonization temperature, the signal at 10 ppm for NH disap-
from 1n–p. To our delight, when the substrate 1n was peared, indicating that that the proton on the nitrogen
used in this reaction, indolodihydropyran-2-one 4n was deprotonated by ZnMe2 rapidly. To further probe
could be produced efficiently by this method. Sub- the mechanism of this reaction, three experiments
stituents in the a-position of hydroxy group in 2-alk- were conducted in the absence of CO2 (Scheme 5).
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
good to excellent yields. The structure of 4o was con- DMF for 5 min followed by quenching with D2O pro-
firmed by an X-ray diffraction study (Figure 1, vided the protonolysis product 3a-d in 34% with D in-
right).[24] With the combination of indole and lactone, corporation of 58% while the same reaction in the ab-
this type of compounds will be potentially useful in sence of Cu
ACHTUNGRTEN(NUNG OAc)2 afforded 3a-d in 32% yield with
medicinal chemistry. 97% of D incorporation after 3 h (Scheme 5), indicat-
In order to show the potential of this protocol, an ing that the reactivity of such intermediate C with Cu
indoloquinolinone exhibiting cytotoxic activity[25] was is much higher: The low D incorporation in the pres-
selected as our target (Scheme 4).[26] Symmetric di- ence of 5 mol% Cu
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
ethynylaniline via Sonogashira coupling followed by C with DMF. This was confirmed by running the reac-
double tosylation. The cyclizative carboxylation of 6 tion in DMF-d7 affording 3a-d with 89% D incorpora-
(5.17 g, 10 mmol) was then conducted under the stan- tion.
dard reaction conditions which was followed by treat-
ment with EDCI and detosylation with Na/naphtha- ducted as shown in Table 4. The reaction could not
lene to afford 1.4 g (61% yield for the three steps) of work well if any one reagent, Cu(OAc)2, CsF, and
indoloquinolinone with a single run, indicating the ZnMe2, was removed from the catalytic system
In addition, several control experiments were con-
AHCTUNGTRENNUNG
practicality of this method.
(Table 4, entries 1–3). In addition, it was observed
Scheme 3. Synthesis of indolodihydropyran-2-ones.
4
asc.wiley-vch.de
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 0000, 000, 0 – 0
ÝÝ
These are not the final page numbers!

Quadri-Synergetic Effect for Highly Effective Carbon Dioxide Fixation
Scheme 4. Synthesis of indoloquinolinone.
Scheme 5. Studies on the formation and reactivity of the indolyl intermediate C.
that CsF or ZnMe2 may both alone promote the for- enones, allylic bromides as compared to the corre-
mation of 2a, albeit in very low yields (5–9%) sponding zinc reagents. However, it is still not very ef-
(Table 4, entries 5 and 6) while with Cu
ACHTUNGTRENNUNG
(5 mol%) alone, the formation of 2a was not ob-
served, however, intermediate C was formed highly placed with KF affording 2a in a lower yield of 82%,
efficiently: the reaction afforded the cycloisomeriza- showing that Cs+ also plays an important role ensur-
tion product 3a in 98% yield (entry 4), indicating that ing a better reactivity of intermediate C towards CO2
indolyl metal intermediates C-Cs and C-Zn react very (compare Scheme 2 with entry 7 in Table 4); when
slowly with CO2 and intermediate C-Cu shows no re- CsF was replaced with Cs2CO3, the yield of 2a is also
activity (Scheme 6). In addition, it should be noted lower [85% vs. 96%, (compare Scheme 2 with entry 8
that the combined reagent of copper and zinc C-Zn- in Table 4)], indicating the effect of Fꢀ for CO2 acti-
ꢀ
Cu is more reactive than C-Zn or C-Cu, which is con- vation via its reaction with CO2 forming FCO2 to in-
sistent with the observation by Knochel et al.[27] that crease the reactivity of the C=O bond in
copper-zinc reagents demonstrate higher reactivity to- CO2.[3a,b,10d,e,28]
wards electrophiles such as aldehydes, acid chlorides,
Adv. Synth. Catal. 0000, 000, 0 – 0
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
5
ÞÞ
These are not the final page numbers!

Suhua Li and Shengming Ma
COMMUNICATIONS
Table 4. Control experiments for mechanistic study.
Entry
Cu(OAc)2
CsF
ZnMe2
Time t [h]
NMR Yield [%]
2a
3a
p
p
p
1
2
3
4
5
6
7
8
9
ꢂ ꢂ
24
24
24
24
28
24
24
24
24
24
20
5
23
0
5
9
82
85
18
14
49
83
50
98
34
64
7
5
43
42
p
ꢂ
p
p
ꢂ
p
ꢂ
ꢂ
p
ꢂ
ꢂ
p
ꢂ
ꢂ
p
p
p
p
p
KF[a]
Cs2CO3
KF[a]
Cs2CO3
p
[b]
[b]
ꢂ
ꢂ
10
[a]
1.5 equiv. of KF were used instead of CsF.
1.5 equiv. of Cs2CO3 were used instead of CsF.
[b]
Scheme 6. Reactivities of different indolyl metal intermediates towards CO2
Thus, it is concluded that the three metals Cu, Cs
and Zn are working together for the efficient forma- CuACHTUNGTRENNUNG
In conclusion, we have developed an efficient
(OAc)2-catalyzed synthesis of indole-3-carboxylic
tion as well as smooth reaction of intermediate C to- acid and indolodihydropyran-2-one from the readily
wards CO2 in the current high-yielding carboxylation available2-alkynylanilines with CO2 in the presence of
reaction with the additional help from Fꢀ activating ZnMe2 and CsF. It is the first example of an anti-nu-
CO2 (Scheme 7).
cleometallation of carbon-carbon triple bonds–car-
boxylation reaction based on CO2 activation. This
concept may be applied to other nucleometallation
reactions. Although the structural nature of the in-situ
generated highly reactive intermediate C surely needs
further attention, the formation and reactivity infor-
mation of metallic reagents unveiled here may be
useful for the design of new reactions of carbon diox-
ide. Further studies in this area are being pursued in
this laboratory.
Scheme 7. A plausible mechanism.
6
asc.wiley-vch.de
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 0000, 000, 0 – 0
ÝÝ
These are not the final page numbers!

Quadri-Synergetic Effect for Highly Effective Carbon Dioxide Fixation
References
Note added in proof: Very recently, Inamoto et al.
reported the synthesis of indolyl-3-carboxylic acids
from o-(1-alkynyl)anilines by using 10 equivalents of
K2CO3 under 10 atm CO2 without any transition
metal catalyst, see: K. Inamoto, N. Asano, Y. Naka-
mura, M. Yonemoto, Y. Kondo, Org. Lett. 2012, 14,
2622–2625.
[1] For recent reviews, see: a) J. Louie, Curr. Org. Chem.
2005, 9, 605; b) T. Sakakura, J.-C. Choi, H. Yasuda,
Chem. Rev. 2007, 107, 2365; c) M. Aresta, A. Dibene-
detto, Dalton Trans. 2007, 2975; d) M. Mori, Eur. J.
Org. Chem. 2007, 4981; e) A. Correa, R. Martꢃn,
Angew. Chem. 2009, 121, 6317; Angew. Chem. Int. Ed.
2009, 48, 6201; f) S. N. Riduan, Y. Zhang, Dalton Trans.
2010, 39, 3347; g) I. I. F. Boogaerts, S. P. Nolan, Chem.
Commun. 2011, 47, 3021; h) K. Huang, C. Sun, Z. Shi,
Chem. Soc. Rev. 2011, 40, 2435; i) M. Cokoja, C. Bruck-
meier, B. Rieger, W. A. Herrmann, F. E. Kꢄhn, Angew.
Chem. 2011, 123, 8662; Angew. Chem. Int. Ed. 2011, 50,
8510; j) Y. Zhang, S. N. Riduan, Angew. Chem. 2011,
123, 6334; Angew. Chem. Int. Ed. 2011, 50, 6210.
[2] a) M. Shi, K. M. Nicholas, J. Am. Chem. Soc. 1997, 119,
5057; b) R. Johansson, O. F. Wendt, Dalton Trans. 2007,
488; c) J. Wu, N. Hazari, Chem. Commun. 2011, 47,
1069; d) T. Mita, J. Chen, M. Sugawara, Y. Sato,
Angew. Chem. 2011, 123, 1429; Angew. Chem. Int. Ed.
2011, 50, 1393; e) T. Mita, M. Sugawara, H. Hasegawa,
Y. Sato, J. Org. Chem. 2012, 77, 2159.
[3] a) K. Ukai, M. Aoki, J. Takaya, N. Iwasawa, J. Am.
Chem. Soc. 2006, 128, 8706; b) J. Takaya, S. Tadami, K.
Ukai, N. Iwasawa, Org. Lett. 2008, 10, 2697; c) T.
Ohishi, M. Nishiura, Z. Hou, Angew. Chem. 2008, 120,
5876; Angew. Chem. Int. Ed. 2008, 47, 5792; d) T.
Ohishi, L. Zhang, M. Nishiura, Z. Hou, Angew. Chem.
2011, 123, 8264; Angew. Chem. Int. Ed. 2011, 50, 8114;
e) H. Ohmiya, M. Tanabe, M. Sawamura, Org. Lett.
2011, 13, 1086.
[4] a) R. Johansson, M. Jarenmark, O. F. Wendt, Organo-
metallics 2005, 24, 4500; b) C. S. Yeung, V. M. Dong, J.
Am. Chem. Soc. 2008, 130, 7826; c) H. Ochiai, M. Jang,
K. Hirano, H. Yorimitsu, K. Oshima, Org. Lett. 2008,
10, 2681.
[5] For transition metal-free carboxylation of organozinc
see: K. Kobayashi, Y. Kondo, Org. Lett. 2009, 11, 2035.
[6] A. Correa, R. Martꢃn, J. Am. Chem. Soc. 2009, 131,
15974.
[7] a) I. I. F. Boogaerts, S. P. Nolan, J. Am. Chem. Soc.
2010, 132, 8858; b) L. Zhang, J. Cheng, T. Ohishi, Z.
Hou, Angew. Chem. 2010, 122, 8852; Angew. Chem.
Int. Ed. 2010, 49, 8670; c) I. I. F. Boogaerts, G. C. Fort-
man, M. R. L. Furst, C. S. J. Cazin, S. P. Nolan, Angew.
Chem. 2010, 122, 8856; Angew. Chem. Int. Ed. 2010, 49,
8674; d) H. Mizuno, J. Takaya, N. Iwasawa, J. Am.
Chem. Soc. 2011, 133, 1251. For transition metal-free
Experimental Section
Typical Procedure for the Preparation of 2-Phenyl-1-
tosyl-1H-indole-3-carboxylic Acid (2a, Table 3,
entry 1)
To an oven-dried Schlenk tube were added 2-alkynylaniline
1a (173.8 mg, 0.500 mmol), CuACHTNUGRTENUNG(OAc)2 (4.5 mg, 0.025 mmol),
CsF (114.1 mg, 0.751 mmol), and 3 mL of DMF under an
argon atmosphere. The mixture was immediately frozen
with a liquid nitrogen bath and the argon inside was com-
pletely replaced with CO2 by using a CO2 balloon (about
1 L). Then the reaction flask was allowed to stand until the
mixture thawed. To the resulting suspension was added
ZnMe2 (1.2M in toluene, 1.25 mL, 1.5 mmol) with a syringe.
Then the resulting mixture was stirred at 558C with a pre-
heated oil bath for 3 h as monitored by TLC. After that, the
resulting mixture was quenched with 3M HCl. The aqueous
layer was extracted with EtOAc (5 mLꢂ5) and the com-
bined organic layer was washed with water (5 mLꢂ2) and
brine, dried over anhydrous Na2SO4, filtered and concentrat-
ed. The crude product was purified by column chromatogra-
phy on silica gel (petroleum ether/ethyl acetate=5/1 to
DCM/CH3OH=20/1) to afford 2a as a white solid; yield:
183.5 mg (94%); mp 230–2318C (petroleum ether/ethyl ace-
tate); 1H NMR (300 MHz, DMSO-d6): d=12.62 (bs, 1H,
CO2H), 8.22 (d, J=8.1 Hz, 1H, ArH), 8.11–8.07 (m, 1H,
ArH), 7.54–7.29 (m, 11H, ArH), 2.32 (s, 3H, Me); 13C NMR
(75 MHz, DMSO-d6): d=164.4, 145.8, 144.5, 135.5, 134.4,
131.0, 130.5, 130.1, 129.0, 127.5, 127.0, 126.6, 125.6, 124.7,
121.8, 114.9, 114.1, 21.0; MS: m/z=391 (M+, 1.18), 91 (100);
IR (neat): n=3400–2300 (br), 1669, 1598, 1549, 1479, 1445,
1374, 1302, 1264, 1241, 1214, 1188, 1170, 1120, 1106, 1088,
1051, 1028 cmꢀ1; anal. calcd. for C22H17NO4S: C 67.50, H
4.38, N 3.58; found: C 67.56, H 4.50, N 3.36.
Acknowledgements
Financial support from the National Basic Research Program
of China (2009CB825300), National Natural Science Founda-
tion of China (20732005) and Project for Basic Research in
Natural Science Issued by Shanghai Municipal Committee of
Science (No. 08dj1400100) is greatly appreciated. We thank
Mr. Xin Huang in this group for reproducing the results pre-
sented in entries 6 and 12 in Table 3 as well as the synthesis
of 4o in Scheme 2.
ꢀ
carboxylation of Ar H, see: e) O. Vechorkin, N. Hirt,
X. Hu, Org. Lett. 2010, 12, 3567.
[8] a) L. J. Gooßen, N. Rodrꢃguez, F. Manjolinho, P. P.
Lange, Adv. Synth. Catal. 2010, 352, 2913; b) D. Yu, Y.
Zhang, Proc. Natl. Acad. Sci. USA 2010, 107, 20184;
c) X. Zhang, W. Zhang, X. Ren, L. Zhang, X. Lu, Org.
Lett. 2011, 13, 2402. For synthesis of 2-alkynoates see:
d) W. Zhang, W. Li, X. Zhang, H. Zhou, X. Lu, Org.
Lett. 2010, 12, 4748.
[9] a) C. M. Williams, J. B. Johnson, T. Rovis, J. Am. Chem.
Soc. 2008, 130, 14936; b) J. Takaya, K. Sasano, N. Iwa-
sawa, Org. Lett. 2011, 13, 1698; c) M. Takimoto, M.
Mori, J. Am. Chem. Soc. 2002, 124, 10008; d) M. Taki-
Adv. Synth. Catal. 0000, 000, 0 – 0
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
7
ÞÞ
These are not the final page numbers!

Suhua Li and Shengming Ma
COMMUNICATIONS
moto, Y. Nakamura, K. Kimura, M. Mori, J. Am.
Chem. Soc. 2004, 126, 5956.
[20] T. Kurisaki, T. Naniwa, H. Yamamoto, H. Imagawa, M.
Nishizawa, Tetrahedron Lett. 2007, 48, 1871.
[10] a) K. Shimizu, M. Takimoto, Y. Sato, M. Mori, Org.
Lett. 2005, 7, 195; b) K. Shimizu, M. Takimoto, M.
Mori, Y. Sato, Synlett 2006, 3182; c) T. Fujihara, T. Xu,
K. Semba, J. Terao, Y. Tsuji, Angew. Chem. 2011, 123,
543; Angew. Chem. Int. Ed. 2011, 50, 523; d) S. Li, W.
Yuan, S. Ma, Angew. Chem. 2011, 123, 2626; Angew.
Chem. Int. Ed. 2011, 50, 2578; e) S. Li, S. Ma, Org.
Lett. 2011, 13, 6046.
[21] K. Hiroya, S. Itoh, ; T. Sakamoto, J. Org. Chem. 2004,
69, 1126.
[22] Crystal data for compound 2d: C22H21NO4S, MW =
395.46, triclinic, space group P-1, final R indices [I>
2s(I)], R1=0.0387, wR2=0.1078; R indices (all data),
R1=0.0435,
wR2=0.1129;
a=9.1308(8) ꢅ,
b=
10.7850(9) ꢅ, c=11.6476(9) ꢅ, a=113.141(2)8, b=
91.466(2)8, g=109.345(2)8, V=979.00(14) ꢅ3, T=
296(2) K, Z=2, reflections collected/unique 11391/3425
(Rint =0.0191), number of observations [>2s(I)] 3036,
parameters: 253. Supplementary crystallographic data
have been deposited at the Cambridge Crystallographic
Data Centre under CCDC 880819. These data can be
obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_re-
quest/cif.
[11] a) M. Takimoto, M. Kawamura, M. Mori, Y. Sato, Syn-
lett 2005, 2019; b) J. Takaya, N. Iwasawa, J. Am. Chem.
Soc. 2008, 130, 15254.
[12] For the Ni(0)-catalyzed cycloaddition of CO2 and
diynes affording pyrones, see: a) J. Louie, J. E. Gibby,
M. V. Farnworth, T. N. Tekavec, J. Am. Chem. Soc.
2002, 124, 15188; b) T. Tsuda, S. Morikawa, R. Sumiya,
T. Saegusa, J. Org. Chem. 1988, 53, 3140; c) T. Tsuda, S.
Morikawa, T. Saegusa, J. Chem. Soc. Chem. Commun.
1989, 9; d) T. Tsuda, S. Morikawa, N. Hasegawa, T.
Saegusa, J. Org. Chem. 1990, 55, 2978; e) T. N. Tekavec,
A. M. Arif, J. Louie, Tetrahedron 2004, 60, 7431.
[13] For reviews on hydrogenation of carbon dioxide into
methanol and formic acid, see: a) P. G. Jessop, T. Ikar-
iya, R. Noyori, Chem. Rev. 1995, 95, 259; b) G. A.
Olah, A. Goeppert, G. K. S. Prakash, J. Org. Chem.
2009, 74, 487.
[14] J. F. Hartwig, in: Organotransition Metal Chemistry
from Bonding to Catalysis, (Eds: J. Murdzek), Universi-
ty Science Books, Sausalito, California, 2010, pp 417–
452.
[15] For reviews, see: a) S. Ma, Acc. Chem. Res. 2003, 36,
701; b) G. Zeni, R. C. Larock, Chem. Rev. 2004, 104,
2285; c) F. Alonso, I. P. Beletskaya, M. Yus, Chem. Rev.
2004, 104, 3079; d) A. S. K. Hashmi, Chem. Rev. 2007,
107, 3180; e) N. T. Patil, Y. Yamamoto, Chem. Rev.
2008, 108, 3395; f) D. L. Reger, Acc. Chem. Res. 1988,
21, 229.
[16] For the limited examples of carboxylation of alkenyl-
boronates, see: refs.[3a–c]; for one substrate of metal-free
carboxylation of alkenylzinc, see: ref.[5]; for Ni(0)-cata-
lyzed carboxylation of in-situ generated alkenylzincs
from alkynes see: refs.[10d,e]; for carboxylation of in-situ
generated alkenyl cuprate see: ref.[10c]
[17] For recent reviews on constructing the indole skeleton,
see: a) S. Cacchi, G. Fabrizi, Chem. Rev. 2011, 111,
PR215; b) J. J. Song, J. T. Reeves, F. Gallou, Z. Tan,
N. K. Yee, C. H. Senanayake, Chem. Soc. Rev. 2007, 36,
1120; c) G. R. Humphrey, J. T. Kuethe, Chem. Rev.
2006, 106, 2875; d) G. Palmisano, A. Penoni, M. Sisti, F.
Tibiletti, S. Tollari, K. M. Nicholas, Curr. Org. Chem.
2010, 14, 2409; e) S. Patil, R. Patil, Curr. Org. Synth.
2007, 4, 201; f) S. Patil, J. K. Buolamwini, Curr. Org.
Synth. 2006, 3, 477; g) S. Cacchi, G. Fabrizi, A. Goggia-
mani, Org. Biomol. Chem. 2011, 9, 641; h) R. Vicente,
Org. Biomol. Chem. 2011, 9, 6469.
[23] a) H. Li, J. Tatlock, A. Linton, J. Gonzalez, T. Jewell,
L. Patel, S. Ludlum, M. Drowns, S. V. Rahavendran, H.
Skor, R. Hunter, S. T. Shi, K. J. Herlihy, H. Parge, M.
Hickey, X. Yu, F. Chau, J. Nonomiya, C. Lewis, J. Med.
Chem. 2009, 52, 1255; b) M. Robles, M. Aregullin, J.
West, E. Rodriguez, Planta Med. 1995, 61, 199; c) K.
Mori, Tetrahedron 1989, 45, 3233; d) A. Behrenswerth,
N. Volz, J. Torꢆng, S. Hinz, S. Brꢆse, C. E. Mꢄller,
Bioorg. Med. Chem. 2009, 17, 2842.
[24] Crystal data for compound 4o: C19H17NO4S, MW =
355.40, monoclinic, space group P21/c, final R indices
[I>2s(I)], R1=0.0328, wR2=0.0874; R indices (all
data), R1=0.0373, wR2=0.0912; a=10.9258(6) ꢅ, b=
19.8349(11) ꢅ, c=7.4799(4) ꢅ, a=908, b=92.511(2)8,
g=908, V=1619.43(15) ꢅ3, T=173(2) K, Z=4, reflec-
tions collected/unique 18474/2845 (Rint =0.0241),
number of observations [>2s(I)] 2550, parameters:
226. Supplementary crystallographic data have been
deposited at the Cambridge Crystallographic Data
Centre under CCDC 880820. These data can be ob-
tained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_re-
quest/cif.
[25] M. Cokoja, C. Bruckmeier, B. Rieger, W. A. Herrmann,
F. E. Kꢄhn, Angew. Chem. 2011, 123, 8662; Angew.
Chem. Int. Ed. 2011, 50, 8510.
[26] a) Z. Shi, Y. Ren, B. Li, S. Lu, W. Zhang, Chem.
Commun. 2010, 46, 3973; b) J. Bergman, R. Engqvist,
C. Stꢇlhandske, H. Wallberg, Tetrahedron 2003, 59,
1033; c) P. Molina, M. Alajarin, A. Vidal, Tetrahedron
1990, 46, 1063.
[27] For reports on reactivity increased by using copper-zinc
reagents, see: a) S. C. Berk, P. Knochel, M. C. P. Yeh, J.
Org. Chem. 1988, 53, 5789; b) E. Hupe, M. I. Calaza, P.
Knochel, Chem. Commun. 2002, 1390; c) P. Knochel,
M. C. P. Yeh, S. C. Berk, J. Talbert, J. Org. Chem. 1988,
53, 2390; d) P. Knochel, J. Am. Chem. Soc. 1990, 112,
7431; e) S. A. Rao, P. Knochel, J. Am. Chem. Soc. 1991,
113, 5735.
[18] a) Y. Yin, W. Ma, Z. Chai, G. Zhao, J. Org. Chem.
2007, 72, 5731; b) Y. Yin, Z. Chai, W. Ma, G. Zhao,
Synthesis 2008, 4036.
[28] D. W. Arnold, S. E. Bradforth, E. H. Kim, D. M. Neu-
mark, J. Chem. Phys. 1995, 102, 3493.
[19] A. Boyer, N. Isono, S. Lackner, M. Lautens, Tetrahe-
dron 2010, 66, 6468.
8
asc.wiley-vch.de
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 0000, 000, 0 – 0
ÝÝ
These are not the final page numbers!

COMMUNICATIONS
Quadri-Synergetic Effect for Highly Effective Carbon
Dioxide Fixation and Its Application to Indoloquinolinone
9
Adv. Synth. Catal. 2012, 354, 1 – 9
Suhua Li, Shengming Ma*
Adv. Synth. Catal. 0000, 000, 0 – 0
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
9
ÞÞ
These are not the final page numbers!