Synthesis of Biaryls by Decarboxylative Hiyama Coupling

Article abstract of DOI:10.1002/cctc.201500068

A trimetallic palladium/copper/silver system has been developed that allows the decarboxylative Hiyama coupling of ortho-substituted aryl carboxylates with trialkoxyarylsilanes to give the corresponding biaryls. The cross-coupling is catalyzed by a Pd/N-heterocyclic carbene complex with silver carbonate aiding its reoxidation. Copper(II) fluoride acts as decarboxylation catalyst, stoichiometric oxidant, and fluoride source. The scope of the protocol is demonstrated by 22 examples, among them aryl halides suitable for further coupling, and the synthetic utility of the products is illustrated by their conversion into carbazoles and 1H-indazoles.

Full text of DOI:10.1002/cctc.201500068

DOI: 10.1002/cctc.201500068
Communications
Synthesis of Biaryls by Decarboxylative Hiyama Coupling
Dmitry Katayev, Benjamin Exner, and Lukas J. Gooßen*[a]
A trimetallic palladium/copper/silver system has been devel-
oped that allows the decarboxylative Hiyama coupling of
ortho-substituted aryl carboxylates with trialkoxyarylsilanes to
give the corresponding biaryls. The cross-coupling is catalyzed
by a Pd/N-heterocyclic carbene complex with silver carbonate
aiding its reoxidation. Copper(II) fluoride acts as decarboxyla-
tion catalyst, stoichiometric oxidant, and fluoride source. The
scope of the protocol is demonstrated by 22 examples, among
them aryl halides suitable for further coupling, and the syn-
thetic utility of the products is illustrated by their conversion
into carbazoles and 1H-indazoles.
the introduction of strained organosilane reagents with en-
hanced reactivity.[7]
Applications of Hiyama couplings include the synthesis of
biologically active biaryls, polymers, sensors, and ligands for
transition-metal catalysts.[8]
Extending the range of possible coupling partners of orga-
nosilanes from aryl (pseudo)halides to carboxylic acids would
be desirable because these substrates are broadly available,
often with complementary structural features.
Decarboxylative couplings have emerged as an advanta-
geous alternative to traditional cross-couplings.[9] Redox-neu-
tral cross-couplings allow the formation of CÀC bonds starting
from aromatic carboxylates and various carbon electrophiles,
albeit at rather high temperatures.[10] The oxidative version of
this reaction, in which carboxylic acids are coupled with
carbon nucleophiles, often proceeds under milder conditions.
Following pioneering work by Myers et al.,[11a] several oxidative
decarboxylative couplings have been reported, including Heck-
type reactions,[11] arylations with CÀH activation,[12] cross-cou-
plings with boronic acids,[13] and decarboxylative heterocou-
plings of two different carboxylic acids.[14] Recent develop-
ments in this field also include oxidative decarboxylative cyan-
ations,[15] sulfoximinations,[16] phosphonations,[17] alkoxyla-
tions,[18] and amidations.[19]
Transition-metal-catalyzed cross-coupling reactions are power-
ful tools for the construction of carbonÀcarbon bonds.[1] The
significance of this field was highlighted by the 2010 Nobel
Prize, which was awarded to R. Heck, E. Negishi, and A. Suzuki.
Among the many organometallic reagents employed in this
context,[2] organosilicon compounds remain particularly chal-
lenging substrates. The carbonÀsilicon bond is relatively stable
(DG=86 kcalmolÀ1)[3] and has a low polarity (DEN=0.65).
Hence, the reactivity of organosilanes is low, which is advanta-
geous for storage and handling, but challenging for the devel-
opment of efficient catalysts for their conversion. Another key
advantage of organosilanes is their low toxicity.[4]
Our desired extension of decarboxylative cross-couplings to
silicon-based carbon nucleophiles was initially restricted by the
low reactivity of these compounds. In the context of a report
on decarboxylative Suzuki couplings, Mino et al. similarly
found that when using a trialkoxy(aryl)silane, rather than the
boron reagent, in a coupling with 2,4,6-trialkoxybenzoic acid,
only unsatisfactory yields were obtained.[13f]
Organosilanes were first coupled with organic halides by Ha-
tanaka and Hiyama (Scheme 1) by using a tris(diethylamino)sul-
fonium difluorotrimethylsilicate (TASF)/Pd catalyst.[5] State-of-
the-art catalysts, for example, [Pd(h3-C3H5)Cl]2, allow the
Hiyama coupling of various substrates including (hetero)aryl,
alkenyl, allyl, and alkynyl silanes.[6] A notable development was
A mechanistic blueprint based on studies of decarboxyla-
tive[20] and Hiyama couplings[21] is shown in Scheme 2. The
mechanism illustrates that the catalyst system would have to
fulfil four requirements. Firstly, a decarboxylation catalyst is re-
quired for the generation of an aryl nucleophile by extrusion
of CO2 from the carboxylate. Secondly, a cross-coupling cata-
lyst needs to take up the carbon nucleophile generated in the
decarboxylation step, as well as that originating from the orga-
nosilane, and eliminate both with the formation of a CÀC
bond. Thirdly, an oxidant is required to reinstate the original
oxidation state of the cross-coupling catalyst. Finally, a base is
needed to activate the organosilane for the transmetalation
step. Several of these tasks may be performed by the same
component, but the catalyst system can be expected to be
complex and the reaction development challenging.
Scheme 1. Traditional versus decarboxylative Hiyama coupling.
[a] Dr. D. Katayev, B. Exner, Prof. Dr. L. J. Gooßen
Department of Organic Chemistry
TU Kaiserslautern
Erwin-Schrçdinger-Str. Geb. 54, 67663 Kaiserslautern (Germany)
E-mail: goossen@chemie.uni-kl.de
Homepage: www.chemie.uni-kl.de/goossen
To explore the feasibility of such a transformation, we chose
the coupling of potassium 2-nitrobenzoate 1a, which under-
goes decarboxylation extraordinarily easily in the presence of
silver, with trimethoxy(phenyl)silane 2a as the model reaction.
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/cctc.201500068.
Part of a Special Issue on Palladium Catalysis. A link to the Table of Con-
tents will appear here once the Special Issue is assembled.
ChemCatChem 0000, 00, 0 – 0
1
ꢀ 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
These are not the final page numbers! ÞÞ

Communications
The presence of the radical quencher 2,2,6,6-tetramethylpi-
peridine-N-oxyl (TEMPO) in the reaction mixture did not com-
pletely suppress the reaction, suggesting that a radical path-
way is not operating (entry 22). In the course of the reaction,
a dark precipitate forms. Analysis by atomic-absorption spec-
troscopy (AAS) revealed that the precipitate contains silver,
copper, palladium, potassium, and silicon species (see the Sup-
porting Information, Table S2).
The reaction mixture was investigated by ESI-MS, but owing
to the complexity of the reaction mixture, the spectra re-
mained inconclusive. Further experiments using customized
MS methods and equipment are underway.
At this stage, we can only speculate about the exact roles of
the individual compounds. We believe that, contrary to our ini-
tial assumption, the silver is not involved in the decarboxyla-
tion step, but aids the reoxidation of palladium(0) to
palladium(II).
Scheme 2. Proposed mechanism for the decarboxylative coupling of aromat-
ic carboxylate salts with aryl silanes.
Having found an efficient catalyst system for the decarboxy-
lative Hiyama reaction, we next investigated the scope with
regard to silanes (Table 2). Various trimethoxy(aryl)silanes bear-
ing common functionalities react smoothly with potassium 2-
Following the above-mentioned considerations, we initially
used 3 mol% Pd(OAc)2 as the cross-coupling catalyst, 2 equiva-
lents of Cu(OAc)2 as the oxidant, and AgF as a fluoride base
and decarboxylation catalyst. Upon stirring overnight
at 1308C, a modest yield of 40% of desired biaryl
product 3aa was obtained (Table 1, entry 1). The ab-
sence of any of these components led to substantial-
Table 1. Optimization of the reaction conditions for the decarboxylative coupling of
potassium 2-nitrobenzoate 1a and trimethoxy(phenyl)silane 2a.[a]
ly lower yields of 3aa, suggesting that all three
metals are required (entries 2–4). Systematic variation
of the reaction conditions revealed that a stoichiomet-
ric amount of fluoride is necessary, and that taken to-
gether, the silver(I) and copper(II) need to amount to
at least 2 equivalents (entries 5–8). This is under-
standable if both metals fulfil the role of stoichio-
metric oxidants. The optimal Cu/Ag ratio was deter-
mined to be 3:1, with Ag2CO3 as the optimal silver
source and CuF2 as source both of copper(II) and
fluoride.
Entry Pd catalyst
Ligand
Additives
[(equiv.)]
Yield of
3aa [%]
1
2
3
4
Pd(OAc)2
–
–
–
–
–
–
–
–
–
Cu(OAc)2 (2)/AgF (1.25)
Cu(OAc)2 (2)/AgF (1.25)
AgF (2.25)
40
–
7
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
PdCl2
Pd(hfac)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
CuF2 (2)
19
5
6
7
8
Cu(OAc)2 (2)/Ag2CO3 (0.25)/CsF (2) 11
Cu(OAc)2 (2)/Ag2CO3 (0.25)/KF (2) 12
Among the palladium catalysts examined, palladi-
um/N-heterocyclic carbene complexes showed the
best reactivity by far (entries 9–18). In the presence
of 1.5 mol% [Pd(IPr)NQ]2, near-quantitative yields of
3aa were obtained.
CuF2 (2)/Ag2CO3 (0.25)
CuF2 (1.5)/Ag2CO3 (0.25)
CuF2 (1.5)/Ag2CO3 (0.25)
CuF2 (1.5)/Ag2CO3 (0.25)
CuF2 (1.5)/Ag2CO3 (0.25)
CuF2 (1.5)/Ag2CO3 (0.25)
61
69
57
66
57
59
53
64
9
–
–
10
11
12
13
14
15
16
17
18
19
20
21
22
PPh3
P(o-Tol)3
Control experiments under the optimized condi-
tions confirmed that all three metal components con-
tribute to these high yields. On the replacement of
silver with copper carbonate, the yield is reduced to
75% (entry 20), and with an excess of AgF, but no
copper, only 11% yield is obtained (entry 21). Inter-
estingly, 3aa is still formed in 28% yield in the ab-
sence of palladium, indicating that a Cu/Ag system is
also able to promote the cross-coupling step, but
with much lower efficiency than palladium (entry 19).
This finding is in good agreement with the literature,
Ag/Cu, Cu/Pd, Ag/Pd, and even monometallic copper
systems[22] have all been found to promote decarbox-
ylative couplings. However, for the specific case of
decarboxylative Hiyama couplings, the trimetallic
system is by far the most effective.
P(p-CF3Ph)3 CuF2 (1.5)/Ag2CO3 (0.25)
XPhos
CuF2 (1.5)/Ag2CO3 (0.25)
CuF2 (1.5)/Ag2CO3 (0.25)
CuF2 (1.5)/Ag2CO3 (0.25)
CuF2 (1.5)/Ag2CO3 (0.25)
CuF2 (1.5)/Ag2CO3 (0.25)
CuF2 (1.5)/Ag2CO3 (0.25)
CuF2 (1.5)/CuCO3·Cu(OH)2 (0.25)
AgF (2.5)
[Pd(p-cinnamyl)(IPr)Cl] –
75
[Pd(IPr)NQ]2
[Pd(IMes)NQ]2
[Pd(IPr)NQ]2
–
[Pd(IPr)NQ]2
[Pd(IPr)NQ]2
[Pd(IPr)NQ]2
–
–
–
–
–
–
–
94 (92)[b]
94
98[c]
28
75
11
45[d]
CuF2 (1.5)/Ag2CO3 (0.25)
[a] Reaction conditions: 1a (0.3 mmol), 2a (0.6 mmol), Pd catalyst (3 mol%/1.5 mol%
for dinuclear complexes), ligand (6 mol%), additives, DMAc (1.5 mL), N2 atmosphere,
19 h. Yields were determined by GC analysis using n-tetradecane as the internal stan-
dard. [b] Yield of isolated product. [c] With 3 equiv. of trimethoxy(phenyl)silane.
[d] With 1 equiv. of TEMPO. hfac=1,1,1,5,5,5-hexafluoroacetylacetonate, IPr=1,3-
bis(2,6-diisopropylphenyl) imidazol-2-ylidene, IMes=1,3-bis(2,4,6-trimethylphenyl)-
imidazol-2-ylidene, NQ=naphthoquinone.
&
ChemCatChem 0000, 00, 0 – 0
www.chemcatchem.org
2
ꢀ 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!

Communications
A control experiment revealed that triethoxy(phenyl)silane
(2b) gives slightly lower yields than trimethoxy(phenyl)silane
(2a) (Table 2, product 3aa).
Table 2. Scope of the decarboxylative Hiyama coupling.[a]
For the example of 2-nitro-1,1’-biphenyl (3ga) the decarbox-
ylative Hiyama reaction was successfully performed on gram
scale, confirming the scalability of the reaction (Scheme 3,
top).
Product
Yield
[%]
Product
Yield
[%]
90
93
88
86
86[b]
87
56
89
87
92
85
Scheme 3. Follow-up functionalizations of 5-chloro-2-nitro-1,1’-biphenyl
3ga. DMAc=Dimethylacetamide.
91
85
81
93
88
88
For the benzoate coupling partner, a nitro substituent in the
ortho position turned out to be vital. Various additional sub-
stituents including chloro, bromo, and fluoro groups were well
tolerated and may serve as handles for further functionaliza-
tion (Table 2, products 3ca, 3ea, 3ja, and 3ka). This confirms
the orthogonality of this decarboxylative reaction with aryl
halide couplings. For carboxylates without ortho-nitro substitu-
ents, which normally also work in the presence of silver, such
as 2-methoxybenzoate, 2-fluorocarboxylate, or thiophen-2-car-
boxylate, only low yields of the products were observed even
at increased temperatures. The formation of a large amount of
homocoupling products prevented isolation of the desired
products. Further optimization of the catalyst system is clearly
required before this transformation can be applied to a full
range of carboxylic acids.
97
84
94
93
95
67
The synthetic utility of the 2-nitrobiaryls was demonstrated
by their conversion into pharmaceutically significant 1H-inda-
zoles[23] and carbazoles.[24] Both reactions involve ortho-directed
CÀH functionalization steps. 1H-Indazole 4 was prepared in
quantitative yield by thermal cyclization of 3ga and N-tosylhy-
drazone.[25] Reductive cyclization of 3ga with microwave irradi-
ation led to the formation of carbazole 5 in 45% isolated yield
(Scheme 3).[26]
[a] Reaction conditions:
1 (1 mmol), [Pd(IPr)NQ]2 (1.5 mol%), Ag2CO3
(25 mol%), CuF2 (1.5 equiv.), DMAc (5 mL), 1308C, 19 h, isolated yields.
[b] Triethoxy(phenyl)silane 2b was used instead of trimethoxy(phenyl)-
silane 2a.
nitrobenzoate (1a) to give the corresponding biaryls in high
yields. Both electron-rich and electron-deficient substrates
were tolerated, and methyl-, methoxy-, trifluoromethyl-,
fluoro-, dimethylamino-, benzo[d]dioxole-substituted nitroben-
zoates, and even the sterically demanding 1-naphthyl deriva-
tive, gave similarly good results. (E)-Trimethoxy(styryl)silane
and trimethoxy(thiophen-3-yl)silane were also shown to be
suitable coupling partners.
In conclusion, a trimetallic Pd/Cu/Ag system efficiently pro-
motes the decarboxylative Hiyama coupling of 2-nitrocarboxy-
lates with various organosilanes. This is the first high-yielding
protocol for the conversion of nontoxic and easy-to-handle,
but rather unreactive, organosilanes in decarboxylative cou-
plings. A key benefit of this approach, in which bromo sub-
stituents remain intact, is its orthogonality to traditional cross-
coupling reactions.
ChemCatChem 0000, 00, 0 – 0
www.chemcatchem.org
3
ꢀ 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
These are not the final page numbers! ÞÞ

Communications
J. Am. Chem. Soc. 2005, 127, 8004–8005; f) Y. Nakao, J. Chen, M. Tanaka,
T. Hiyama, J. Am. Chem. Soc. 2007, 129, 11694–11695; g) S. E. Denmark,
C. S. Regens, Acc. Chem. Res. 2008, 41, 1486–1499; h) S. E. Denmark,
R. C. Smith, W.-T. T. Chang, J. M. Muhuhi, J. Am. Chem. Soc. 2009, 131,
3104–3118.
Experimental Section
Synthesis of 3aa
Under a nitrogen atmosphere, a 20 mL vessel was charged with
potassium 2-nitrobenzoate 1a (205 mg, 1.00 mmol), [Pd(IPr)NQ]2
(19.6 mg, 15.00 mmol), and Ag2CO3 (69.6 mg, 0.25 mmol). In a glove-
box, CuF2 (154 mg, 1.50 mmol) was added and the vessel was
sealed. Degassed N,N-dimethylacetamide (5 mL) and trimethoxy-
(phenyl)silane 2a (397 mg, 2.00 mmol) were then injected, and the
mixture was stirred at 1308C for 19 h. During the reaction, a dark
precipitate containing Pd (1.3%), Ag (33.1%), Cu (34.9%), K
(15.1%), Si (20.2%) was formed, which was removed by filtration
through Celite. The Celite was washed with 3ꢁ5 mL ethyl acetate.
The filtrate was concentrated, and product 3aa was isolated from
the residue by flash column chromatography (SiO2, ethyl acetate/n-
hexane gradient) as a yellow oil in 90% yield (179 mg, 0.89 mmol).
1H NMR (400 MHz, CDCl3): d=7.87 (dd, J=8.0, 1.3 Hz, 1H), 7.61–
7.66 (m, 1H), 7.40–7.53 (m, 5H), 7.32–7.36 ppm (m, 2H); 13C NMR
(101 MHz, CDCl3): d=149.3, 137.3, 136.3, 132.3, 131.9, 128.6, 128.2,
128.1 (2 C), 127.8 (2 C), 124.1 ppm; IR (neat): n˜ =3062 (w), 1520
(vs), 1472 (w), 1351 (s), 1163 (w), 1075 (w), 1009 (w), 955 (w), 852
(m), 770 (m), 738 (vs), 696 (vs), 666 cmÀ1 (s); MS (EI): m/z: 198.0 (5)
[M+], 182.0 (45), 170.9 (100), 154.1 (19), 152.1 (38), 143.2 (29), 115.1
(51), 50.0 (22); elemental anal. (%) calcd. for C12H9NO2: C 72.35; H
4.55; N 7.03; found: C 72.37; H 4.59; N 7.02.
[8] a) J. M. Buriak, Chem. Rev. 2002, 102, 1271–1308; b) C. Bolm, J. P. Hilde-
brand, K. MuÇiz, N. Hermanns, Angew. Chem. Int. Ed. 2001, 40, 3284–
3308; Angew. Chem. 2001, 113, 3382–3407.
[9] a) L. J. Gooßen, N. Rodrꢅguez, K. Gooßen, Angew. Chem. Int. Ed. 2008, 47,
3100–3120; Angew. Chem. 2008, 120, 3144–3164; b) N. Rodrꢅguez, L. J.
Gooßen, Chem. Soc. Rev. 2011, 40, 5030–5048; c) W. I. Dzik, P. P. Lange,
L. J. Gooßen, Chem. Sci. 2012, 3, 2671–2678.
[10] a) L. J. Gooßen, G. Deng, L. M. Levy, Science 2006, 313, 662–664; b) P.
Forgione, M.-C. Brochu, M. St-Onge, K. H. Thesen, M. D. Bailey, F. Bilo-
deau, J. Am. Chem. Soc. 2006, 128, 11350–11351; c) J.-M. Becht, C.
Catala, C. Le Drian, A. Wagner, Org. Lett. 2007, 9, 1781–1783; d) L. J.
Gooßen, B. Zimmermann, C. Linder, N. Rodrꢅguez, P. P. Lange, J. Hartung,
Adv. Synth. Catal. 2009, 351, 2667–2674; e) J. Cornella, I. Larrosa, Syn-
thesis 2012, 44, 653–676; f) B. Song, T. Knauber, L. J. Gooßen, Angew.
Chem. Int. Ed. 2013, 52, 2954–2958; Angew. Chem. 2013, 125, 3026–
3030.
[11] a) A. G. Myers, D. Tanaka, M. R. Mannion, J. Am. Chem. Soc. 2002, 124,
11250–11251; b) P. Hu, J. Kan, W. Su, M. Hong, Org. Lett. 2009, 11,
2341–2344; c) L. J. Gooßen, B. Zimmermann, T. Knauber, Beilstein J. Org.
Chem. 2010, 6, No. 43; d) Z. Fu, S. Huang, W. Su, M. Hong, Org. Lett.
2010, 12, 4992–4995; e) Z.-M. Sun, J. Zhang, P. Zhao, Org. Lett. 2010,
12, 992–995; f) M. Zhang, J. Zhou, J. Kan, M. Wang, W. Su, M. Hong,
Chem. Commun. 2010, 46, 5455–5457; g) X. Zhou, J. Luo, J. Liu, S. Peng,
G.-J. Deng, Org. Lett. 2011, 13, 1432–1435.
[12] a) A. Voutchkova, A. Coplin, N. E. Leadbeater, R. H. Crabtree, Chem.
Commun. 2008, 6312–6314; b) J. Cornella, P. Lu, I. Larrosa, Org. Lett.
2009, 11, 5506–5509; c) H.-P. Bi, L. Zhao, Y.-M. Liang, C.-J. Li, Angew.
Chem. Int. Ed. 2009, 48, 792–795; Angew. Chem. 2009, 121, 806–809;
d) F. Zhang, M. F. Greaney, Angew. Chem. Int. Ed. 2010, 49, 2768–2771;
Angew. Chem. 2010, 122, 2828–2831; e) C. Wang, S. Rakshit, F. Glorius, J.
Am. Chem. Soc. 2010, 132, 14006–14008; f) H.-P. Bi, Q. Teng, M. Guan,
W.-W. Chen, Y.-M. Liang, X. Yao, C.-J. Li, J. Org. Chem. 2010, 75, 783–
788.
[13] a) M. Yamashita, K. Hirano, T. Satoh, M. Miura, Chem. Lett. 2010, 39, 68–
69; b) C. Feng, T.-P. Loh, Chem. Commun. 2010, 46, 4779–4781; c) M. Li,
C. Wang, H. Ge, Org. Lett. 2011, 13, 2062–2064; d) J.-J. Dai, J.-H. Liu, D.-
F. Luo, L. Liu, Chem. Commun. 2011, 47, 677–679; e) A. Wang, X. Li, J.
Liu, Q. Gui, X. Chen, Z. Tan, K. Xie, Synth. Commun. 2014, 44, 289–295;
f) T. Mino, E. Yoshizawa, K. Watanabe, T. Abe, K. Hirai, M. Sakamoto, Tet-
rahedron Lett. 2014, 55, 3184–3188.
Acknowledgements
We thank the Swiss National Science Foundation (fellowship to
D.K.) and the Collaborative Research Centre SFB/TRR 88 “3MET”
for financial support, Dr. Kꢀthe Gooßen for help with the manu-
script and Joachim Hewer for the measurement of ESI-MS spec-
tra.
Keywords: cross-coupling
coupling · organosilanes · palladium
·
decarboxylation
·
Hiyama
[1] a) N. Miyaura, A. Suzuki, Chem. Rev. 1995, 95, 2457–2483; b) A. Suzuki,
J. Organomet. Chem. 1999, 576, 147–168; c) A. de Meijere, F. Diederich
in Metal-Catalyzed Cross-Coupling Reactions, Wiley-VCH, 2004; d) N. T. S.
Phan, M. Van Der Sluys, C. W. Jones, Adv. Synth. Catal. 2006, 348, 609–
679; e) C. Liu, H. Zhang, W. Shi, A. Lei, Chem. Rev. 2011, 111, 1780–
1824; f) K. Tanaka in Transition-Metal-Mediated Aromatic Ring Construc-
tion, Wiley, Hoboken, New Jersey, 2013; g) X. Ribas, I. Gꢂell, Pure Appl.
Chem. 2014, 86, 345–360; h) F.-X. Felpin, Synlett 2014, 25, 1055–1067;
i) C. E. I. Knappke, S. Grupe, D. Gꢃrtner, M. Corpet, C. Gosmini, A. Jacobi
von Wangelin, Chem. Eur. J. 2014, 20, 6828–6842.
[2] a) T. Hiyama, E. Shirakawa in Cross-Coupling Reactions (Ed.: P. N.
Miyaura), Springer, Berlin, 2002, pp. 61–85; b) A. Molnꢄr in Palladium-
Catalyzed Coupling Reactions: Practical Aspects and Future Developments,
Wiley-VCH, Weinheim, Germany, 2013.
[3] W. C. Steele, L. D. Nichols, F. G. A. Stone, J. Am. Chem. Soc. 1962, 84,
4441–4445.
[4] Y. Nakao, T. Hiyama, Chem. Soc. Rev. 2011, 40, 4893–4901.
[5] a) Y. Hatanaka, T. Hiyama, J. Org. Chem. 1988, 53, 918–920; b) Y. Hatana-
ka, T. Hiyama, Synlett 1991, 1991, 845–853.
[6] H. F. Sore, W. R. J. D. Galloway, D. R. Spring, Chem. Soc. Rev. 2012, 41,
1845–1866.
[7] a) S. E. Denmark, R. F. Sweis, J. Am. Chem. Soc. 2004, 126, 4876–4882;
b) S. E. Denmark, M. H. Ober, Adv. Synth. Catal. 2004, 346, 1703–1714;
c) A. K. Sahoo, T. Oda, Y. Nakao, T. Hiyama, Adv. Synth. Catal. 2004, 346,
1715–1727; d) Y. Nakao, H. Imanaka, A. K. Sahoo, A. Yada, T. Hiyama, J.
Am. Chem. Soc. 2005, 127, 6952–6953; e) S. E. Denmark, S. A. Tymonko,
[14] a) J. Cornella, H. Lahlali, I. Larrosa, Chem. Commun. 2010, 46, 8276–
8278; b) P. Hu, Y. Shang, W. Su, Angew. Chem. Int. Ed. 2012, 51, 5945–
5949; Angew. Chem. 2012, 124, 6047–6051.
[15] a) K. Ouchaou, D. Georgin, F. Taran, Synlett 2010, 2010, 2083–2086; b) J.
Liu, C. Fan, H. Yin, C. Qin, G. Zhang, X. Zhang, H. Yi, A. Lei, Chem.
Commun. 2014, 50, 2145–2147.
[16] D. L. Priebbenow, P. Becker, C. Bolm, Org. Lett. 2013, 15, 6155–6157.
[17] X. Li, F. Yang, Y. Wu, Y. Wu, Org. Lett. 2014, 16, 992–995.
[18] S. Bhadra, W. I. Dzik, L. J. Goossen, J. Am. Chem. Soc. 2012, 134, 9938–
9941.
[19] J. Liu, Q. Liu, C. Qin, R. Bai, X. Qi, Y. Lan, A. Lei, Angew. Chem. Int. Ed.
2014, 53, 502–506; Angew. Chem. 2014, 126, 512–516.
[20] A. Fromm, C. van Wꢂllen, D. Hackenberger, L. J. Gooßen, J. Am. Chem.
Soc. 2014, 136, 10007–10023.
[21] A. Gordillo, M. A. OrtuÇo, C. Lꢆpez-Mardomingo, A. Lledꢆs, G. Ujaque, E.
de Jesffls, J. Am. Chem. Soc. 2013, 135, 13749–13763.
[22] R. Shang, Y. Fu, Y. Wang, Q. Xu, H.-Z. Yu, L. Liu, Angew. Chem. Int. Ed.
2009, 48, 9350–9354; Angew. Chem. 2009, 121, 9514–9518.
[23] a) H. Cerecetto, A. Gerpe, M. Gonzꢄlez, V. J. Arꢄn, C. O. de Ocꢄriz, Mini-
Rev. Med. Chem. 2005, 5, 869–878; b) A. Schmidt, A. Beutler, B. Snovy-
dovych, Eur. J. Org. Chem. 2008, 4073–4095; c) A. Thangadurai, M.
Minu, S. Wakode, S. Agrawal, B. Narasimhan, Med. Chem. Res. 2012, 21,
1509–1523.
[24] a) K. C. Das, D. P. Chakraborty, P. K. Bose, Experientia 1965, 21, 340; b) K.
Sakano, K. Ishimaru, S. Nakamura, J. Antibiot. 1980, 33, 683–689; c) S.
&
ChemCatChem 0000, 00, 0 – 0
www.chemcatchem.org
4
ꢀ 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!

Communications
Omura, Y. Sasaki, Y. Iwai, H. Takeshima, J. Antibiot. 1995, 48, 535–548;
d) H.-J. Knçlker, K. R. Reddy, Chem. Rev. 2002, 102, 4303–4427.
[25] Z. Liu, L. Wang, H. Tan, S. Zhou, T. Fu, Y. Xia, Y. Zhang, J. Wang, Chem.
Commun. 2014, 50, 5061–5063.
[26] J. T. Kuethe, K. G. Childers, Adv. Synth. Catal. 2008, 350, 1577–1586.
Received: January 26, 2015
Revised: March 14, 2015
Published online on && &&, 0000
ChemCatChem 0000, 00, 0 – 0
www.chemcatchem.org
5
ꢀ 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
These are not the final page numbers! ÞÞ

COMMUNICATIONS
D. Katayev, B. Exner, L. J. Gooßen*
&& – &&
Synthesis of Biaryls by
Decarboxylative Hiyama Coupling
Three metals are better than one: A
trimetallic Pd/Cu/Ag system allows the
decarboxylative Hiyama coupling of
ortho-substituted aryl carboxylates with
trialkoxyarylsilanes in high yields. A Pd/
N-heterocyclic carbene complex catalyz-
es the cross-coupling reaction with
silver carbonate supporting reoxidation
of the complex. Copper(II) fluoride acts
as decarboxylaton catalyst, stoichiomet-
ric oxidant, and fluoride source, neces-
sary to activate organosilanes.
DMAc=Dimethylacetamide.
&
ChemCatChem 0000, 00, 0 – 0
www.chemcatchem.org
6
ꢀ 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!