Aerobic oxidative coupling between carbon nucleophiles and allylic alcohols: A strategy to construct β-(hetero)aryl ketones and aldehydes through hydrogen migration

Article abstract of DOI:10.1002/chem.201302962

Wacker heck of a reaction: A highly efficient Pd^II-catalyzed intermolecular oxidative-coupling reaction is reported, inspired by the fundamental Heck and Wacker processes. The (hetero)aryl-PdX species, originating from C-H activation step or desulfonyl hydrazides, coupled with allylic alcohols by using oxygen as the sole oxidant (see scheme). Copyright

Full text of DOI:10.1002/chem.201302962

DOI: 10.1002/chem.201302962
Aerobic Oxidative Coupling between Carbon Nucleophiles and Allylic
Alcohols: A Strategy to Construct b-(Hetero)Aryl Ketones and Aldehydes
through Hydrogen Migration
Liangbin Huang, Ji Qi, Xia Wu, Wanqing Wu, and Huanfeng Jiang*[a]
Since the early 1970s, the Pd-catalyzed Heck reaction has
become a powerful tool to prepare substituted olefins.[1,2]
The main challenges in the intermolecular Heck reaction
are controlling the regioselectivity and high selective b-H
elimination when olefins without a significant electronic dif-
ference at the two olefinic sites are used as the substrates.[3]
The groups of Stahl and Zhou recently reported ligand-con-
trolled regioselectivity in the synthesis substituted olefins
through Heck-type coupling of alkenes with vinylboronic
acids and aryl triflates.[3f,4] To solve the problem of selective
b-H elimination, Sigman and co-workers designed palladium
substrate scope is limited to ortho-substituted benzoic acids.
Secondly, stoichiometric amounts of Ag salts were used as
the oxidant. Herein, we present a palladium-catalyzed aero-
bic oxidative coupling of allylic alcohols with (hetero)aryl
nucleophiles to construct b-(hetero)aryl ketones and alde-
hydes.
Recently, increasing interest has been focused on PdII-cat-
[9]
alyzed C H activation and decarboxylation,[10] including
À
its derivatives of carboxylate variants,[11] instead of Ar X
À
(X=halide, OTf and metal; Tf=triflate) for cross-coupling
reactions. They provided complementary approaches for ob-
taining carbon nucleophiles. On one hand, arylsulfonyl hy-
drazides are cheap and readily available carbon nucleophiles
used for oxidative cross-coupling reactions. On the other
hand, (hetero)arene derivatives are of great importance as
building blocks for pharmaceuticals and bioactive com-
pounds. Evidently, the direct utilization of allyl alcohols cou-
pling with those carbon nucleophiles to obtain b-(hetero)-
À
catalysts that were capable of distinguishing C H bonds on
the basis of relative bond strength.[5] Jiao found that b-H
elimination is highly chemoselectively controlled in a ligand-
free system when allyl esters reacted with carbon electro-
philes or carbon nucleophiles, due to chelation between O
and Pd atoms.[6] Lei and Nacci achieved the highly selective
arylation of allyl alcohols through redox-neutral pathway
with iodobenzene or the oxidative approach with benzoboric
acid, respectively. [Eq. (1)].[7] Recently, Pd-catalyzed oxida-
tive coupling between benzoic acids and allyl alcohols lead-
ing to b-aryl ketones was reported.[8] However, some draw-
backs of this method may limit its application. Firstly, the
AHCTUNGTREGaNNNU ryl ketones and aldehydes by using oxygen as the sole oxi-
dant would be a fascinating approach [Eq. (2)]. In addition,
À
the frequently used strategies for C H bond alkylation are
the hydroarylation of alkenes as well as direct alkylation
with alkyl halides. The oxidative coupling between (hetero)-
arene and allyl alcohols provides an alternative approach
[12]
À
for C H alkylation.
The inspection of the coupling reaction between indole
(1) and allyl alcohol (2a) was chosen as a model reaction
for the optimization studies (Table 1). Initially, we examined
the feasibility of this transformation by using the reaction
À
conditions previously established for the C H bond activa-
tion of indole.[13] Among a number of tested oxidants,
Ag2CO3 provided the highest yield of the desired product
with 21% (Table 1, entries 1–5). Increasing the amount of
the oxidant did not give the improved results (Table 1,
entry 6). Gratifyingly, when N-methyl indole was chosen as
the substrate for this transformation, with 1.2 equivalent of
2a and 1.5 equivalent of Ag2CO3 conducted in 2 mL of
HOAc at 808C in the presence of 5 mol% of PdACTHNURGTNEUNG(OAc)2, the
desired oxidative alkylation product 3a was achieved in
58% yield (Table 1, entry 7). And the structure of 3a was
confirmed by NMR spectroscopy (for details see Supporting
Information). Through screening the oxidants, we found that
oxygen was the best for this transformation (Table 1, en-
tries 7–9). More satisfying isolated yield (92%) could be ob-
tained by decreasing reaction temperature to room tempera-
[a] L. Huang, J. Qi, X. Wu, W. Wu, Prof. Dr. H. Jiang
School of Chemistry and Chemical Engineering
South China University of Technology
Guangzhou 510640 (P. R. China)
E-mail: jianghf@scut.edu.cn
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201302962.
15462
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 15462 – 15466

COMMUNICATION
Table 1. Screening reaction conditions of the Pd-catalyzed oxidative al-
kylation of indole.[a]
Table 2. Pd-catalyzed oxidative alkylation of indoles with allyl alcohols.[a]
Entry
Oxidant
Cu(OAc)2
Solvent
Catalyst
R
Yield [%][b]
1
2
3
4
G
DMA
DMA
DMA
DMA
CH3COOH
DMA
HOAc
HOAc
HOAc
HOAc
HOAc
CH3CN
DMSO
HOAc
HOAc
HOAc
Pd
Pd
Pd
Pd
Pd
Pd
Pd
Pd
Pd
Pd
Pd
Pd
Pd
–
N
R=H
R=H
R=H
R=H
R=H
R=H
R=Me
R=Me
R=Me
R=Me
R=Me
R=Me
R=Me
R=Me
R=Me
R=Ac
13
trace
21
trace
17
12
58
29
73
86
97(92)
N. R.
N. R.
N.R.
Trace
N.R.
BQ
Ag2CO3
1 atm O2
Ag2CO3
Ag2CO3
Ag2CO3
5
6[c]
7
8
9
Cu
N
1 atm O2
1 atm O2
1 atm O2
1 atm O2
1 atm O2
1 atm O2
1 atm O2
1 atm O2
10[d]
11[e]
12[e]
13[e]
14[e]
15[e]
16[e]
PdCl2
Pd(OAc)2
AHCTUNGTRENNUNG
[a] Unless otherwise noted, the reaction was carried out with
(0.50 mmol), 2a (1.2 equiv), oxidant (0.75 mmol), catalyst
1
(0.025 mmol), solvent (2 mL), 808C, overnight, under N2. [b] The yield
was determined by GC analysis with naphthalene as the internal stan-
dard. Data in parentheses is the yield of isolated product. [c] Oxidant
(1 mmol) was used. [d] 508C. [e] Room temperature.
[a] Unless otherwise noted, the reactions were carried out with
1
(0.50 mmol),
2
(1.2 equiv), oxidant (0.75 mmol), PdACHTUNGTRENNUNG(OAc)2
(0.025 mmol), in HOAc (2 mL), under 1 atm of O2.
ture (Table 1, entries 10 and 11). The acidic solvent was es-
sential for this reaction (Table 1, entries 12 and 13). Control
reactions demonstrated that 3a was not formed in the ab-
sence of Pd catalyst. Additionally, electron-deficient N-Ac
indole failed to give the corresponding product.
With the optimal reaction conditions in hand, we next ex-
plored the generality of the reaction with other substituted
indoles and allyl alcohols under the optimized conditions.
Various allyl alcohols were employed to couple with 1-
methyl-1H-indole. It is noteworthy that the allyl secondary
alcohols were converted into the corresponding b-indole ke-
tones in high yields at higher temperature (Table 2, 3b and
c). The sole chemical selectivity can be obtained when the
converted to the b-thiophene aldehydes and ketone with
moderate to good yields (Table 3, 3n and o). It is worth
mentioning that 3p could be obtained through Heck reac-
tion of 2-bromothiophene with but-3-en-2-one, followed by
an oxidative Heck reaction with allyl alcohol. Similarly, both
electron-rich and electron-deficient 2-substituted furans
could be converted to the b-furan ketones (Table 3, 3q
and r).
Table 3. Pd-catalyzed oxidative alkylation of heterocycles with allyl alco-
hols.[a]
À
substrate contains more than one C C double bond
(Table 2, 3d). Subsequently, a series of substituted indoles
were found to be suitable substrates for this transformation.
The oxidative alkylation of 7-methyl indole with allyl alco-
hol proceeded at room temperature to give the correspond-
ing product in 88% yield (Table 2, 3e). Different 5-substi-
tuted indoles, including some with electron-donating groups
(R=Me, OMe) and some with electron-withdrawing groups
(R=F, Cl, CN), were converted into the corresponding b-
indole ketones and aldehydes with good to excellent yields
À
[a] Unless otherwise noted, the reactions were carried out with
(Table 2, 3 f–k). To our delight, the C H activation occurred
1
(0.50 mmol),
2
(1.2 equiv), oxidant (0.75 mmol), PdACHTUNGTRENNUNG(OAc)2
at the C-2 position when 3-methyl indole was used as the
substrate (Table 2, 3l). Additionally, N-benzyl substituted
indole was also suitable substrate for this transformation
(Table 2, 3m).
(0.025 mmol), in HOAc (2 mL), under 1 atm of O2.
After the successful application of heterocyclic nucleo-
philes for this transformation, we looked to expand the
scope to aryl-nucleophiles, originating from decarboxylation
Then, we looked forward to expanding the scope to other
heterocycles. To our delight, 2-substituted thiophenes were
Chem. Eur. J. 2013, 19, 15462 – 15466
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
15463

H. Jiang et al.
Table 4. Pd-catalyzed oxidative coupling reactions between arylsulfonyl
hydrazides 4 and allyl alcohols 2.
of carboxylic acids. It was known that a limitation of decar-
boxylative coupling was that the substrates are usually limit-
ed to ortho-substituted benzoic acids.[8,10] With the develop-
ment of decarboxylative coupling, aryl phosphonic acids,
aryl sulfinic acids, and arylsulfonyl hydrazides[11,14] have
been described as the source of aryl group without the
ortho-substituted limitation. To further address the scope,
selectivity, and productivity issues, we chose arylsulfonyl hy-
drazides as the coupling partners with allylic alcohols for
this oxidative-coupling reaction through selective b-hydride
elimination to construct b-aryl ketones.
Fortunately, we found that the reaction of 4-methylbenze-
nesulfonohydrazide (4a) (0.33 mmol) with 2b (0.5 mmol)
conducted in a DMSO/DMF (1:20) solvent system at 1208C
in the presence of 10 mol% of PdACTHNUTRGEN(UNG OAc)2, and nBu4NBr
(0.5 mmol) under 1 atm O2 gave the desired product 5a in
84% yield (Table 4; see Supporting Information for details).
We next examined other substrates in this Pd-catalyzed oxi-
dative Heck reaction. Under the optimized conditions, 4a
[a] Unless otherwise noted, the reactions were carried out with
4
(0.33 mmol), 2 (0.5 mmol), Pd(OAc)2 (10 mol%), nBu4NBr (0.5 mmol),
AHCTUNGTRENNUNG
DMF/DMSO=20:1 (3 mL), H2O (0.2 mL) under 1 atm of O2 at 1208C
for 2–12 h. [b] Without adding H2O (0.2 mL) under 1 atm of O2 at 708C.
tions [Eq. (4)]. It indicated that 5a was not formed via the
protonolysis of intermediate D by D2O.[16]
On the basis of the above results, a tentative mechanism
for the Pd-catalyzed oxidative coupling reaction between
(hetero)arenes and allylic alcohols through selective b-H
elimination to synthesize b-(hetero)aryl ketones and alde-
hydes was proposed (Scheme 1). When aromatic heterocy-
coupled with a range of p-substituted 1-phenylprop-2-en-1-
ols in modest to good yields (Table 4). In contrast with the
excellent yields of 5g and h, the strong electron-donating
groups decreased the yields of the corresponding products
(Table 4, 5b–d). These reactions were compatible with furan
cles were used as the substrates, the arylpalladium species I
II
À
was formed through the Pd -catalyzed C H activation of ar-
omatic heterocycles. In the presence of oxygen, intermediate
C could be obtained through the sequent b-H elimination
and loss of nitrogen from intermediate B. Similarly, the
À
and C C double bond moieties (Table 4, 5j and k). It was
interesting to note that benzenesulfonohydrazide with elec-
tron-withdrawing or electron-donating groups are also suit-
ACHTUNGTRENNUNGable substrates for this transformation. When alkyl-substitut-
ed allylic alcohols were used as the coupling partner, the re-
action temperature can be lowered to 708C and without
adding 0.2 mL of water (Table 4, 5o–y).
Encouraged by these promising results, we further per-
formed the d-labelled experiments. 4-methylbenzenesulfono-
hydrazide was employed to couple with [D]-1-phenylprop-2-
en-1-ol under the standard conditions [Eq. (3)]. It was as ex-
pected that a-[D]-b-aryl ketone was the sole product with-
out the b-D elimination product.[8,12,15] No [D]-labelled prod-
uct could be detected when 0.2 mL D2O was added to the
cross coupling between 4-methylbenzenesulfonohydrazide
(4a) and 1-phenylprop-2-en-1-ol under the standard condi-
Scheme 1. Proposed catalytic cycle.
15464
www.chemeurj.org
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 15462 – 15466

Aerobic Oxidative Coupling
COMMUNICATION
China (973 Program) (2011CB808600), the Changjiang Scholars and In-
novation Team Project of Ministry of Education, Doctoral Fund of Min-
istry of Education of China(20090172110014) and Guangdong Natural
Science Foundation (10351064101000000) for financial support.
elimination of SO2 from complex C generated ArPdX,
which was inserted by the allylic alcohols to give intermedi-
ate II. The selective b-H elimination from intermediate II
generated PdII species III, which then inserted into the enol
to afford the critical intermediate IV. This process realized
the hydrogen transfer, just like the Wacker process.[17] The
desired products could then be formed through two contro-
versial approaches: b-H elimination from a-OH groups or
the anion-mediated reductive elimination.[17a]
Keywords: Heck reaction · hydrogen migration · oxidative
alkylation · oxygen · palladium
In order to further demonstrate the generality of this type
of catalytic cycle, we chose (E)-styrylboronic acid as the
source of alkenyl nucleophile to couple with allylic alco-
hols.[7] Fortunately, we isolated the corresponding b-alkenyl
ketone and aldehyde products in 73 and 58% yields, respec-
tively (Scheme 2).
[1] a) M. Oestreich, The Mizoroki–Heck reaction, Wiley, Hoboken,
2008; b) R. F. Heck, J. P. Nolley, J. Org. Chem. 1972, 37, 2320; c) T.
Mizoroki, K. Mori, A. Ozaki, Bull. Chem. Soc. Jpn. 1971, 44, 581;
d) R. F. Heck, Acc. Chem. Res. 1979, 12, 146; e) W. Cabri, I. Can-
AHCTUNGTREGdNNUN iani, Acc. Chem. Res. 1995, 28, 2; f) A. F. Littke, G. C. Fu, J. Am.
Chem. Soc. 2001, 123, 6989; g) B. P. Carrow, J. F. Hartwig, J. Am.
Chem. Soc. 2010, 132, 79.
[2] a) I. P. Beletskaya, A. V. Cheprakov, Chem. Rev. 2000, 100, 3009;
b) K. C. Nicolaou, P. G. Bulger, D. Sarlah, Angew. Chem. 2005, 117,
4516; Angew. Chem. Int. Ed. 2005, 44, 4442.
[3] a) G. D. Daves, A. Hallberg, Chem. Rev. 1989, 89, 1433; b) W. Cabri,
I. Candiani, A. Bedeschi, R. Santi, J. Org. Chem. 1990, 55, 3654;
c) K. S. A. Vallin, M. Larhed, A. Hallberg, J. Org. Chem. 2001, 66,
4340; d) J. Ruan, J. Xiao, Acc Chem. Res. 2011, 44, 614; e) J. Mo, J.
Xiao, Angew. Chem. 2006, 118, 4258; Angew. Chem. Int. Ed. 2006,
45, 4152; f) J. Mo, L. Xu, J. Ruan, S. Liu, J. Xiao, Chem. Commun.
2006, 3591; g) R. Matsubara, A. C. Gutierrez, T. F. Jamison, J. Am.
Chem. Soc. 2011, 133, 19020; h) J. Ruan, J. A. Iggo, N. G. Berry, J.
Xiao, J. Am. Chem. Soc. 2010, 132, 16689.
Scheme 2. Pd-catalyzed oxidative coupling between alkenyl nucleophile
and allylic alcohol.
In conclusion, we have developed a simple and efficient
method for the Pd-catalyzed oxidative coupling reaction be-
tween allylic alcohols and (hetero)arenes and alkenyl nucle-
ophiles to construct b-aryl/alkenyl ketones and aldehydes
through selective b-H elimination. This work opens up
a new approach to realize the selective b-H elimination in
Pd-catalyzed oxidative Heck reaction of electronically non-
biased olefins. Tentative mechanistic studies indicate the hy-
drogen transfer might go through the Wacker oxidative pro-
cess and may be a significant model to study the Wacker ox-
idation. Further studies into the use of unactivated arenes as
the source of aryl nucleophiles, as well as detailed mechanis-
tic investigations, are underway in our laboratory.
[4] a) L. Qin, X. Ren, Y. Lu, Y. Li, J. Zhou, Angew. Chem. 2012, 124,
6017; Angew. Chem. Int. Ed. 2012, 51, 5915.
[5] Selective b-H elimination in oxidative Heck reactions: a) J. Le Bras,
J. Muzart, Chem. Rev. 2011, 111, 1170; b) J. Le Bras, J. Muzart, Tet-
rahedron 2012, 68, 10065; c) Y. Su, N. Jiao, Org. Lett. 2009, 11, 2980;
d) P. Hu, J. Kan, W. Su, M. Hong, Org. Lett. 2009, 11, 2341; e) C.
Zhu, J. R. Falck, Org. Lett. 2011, 13, 1214; f) C. Zhu, J. R. Falck,
Angew. Chem. 2011, 123, 6756; Angew. Chem. Int. Ed. 2011, 50,
6626; g) C. Zheng, D. Wang, S. S. Stahl, J. Am. Chem. Soc. 2012,
134, 16496; h) A. S. Tsai, M. Brasse, R. G. Bergman, J. A. Ellman,
Org. Lett. 2011, 13, 540.
[6] a) D. Pan, A. Chen, Y. Su, W. Zhou, S. Li, W. Jia, J. Xiao, Q. Liu, L.
Zhang, N. Jiao, Angew. Chem. 2008, 120, 4807; Angew. Chem. Int.
Ed. 2008, 47, 4729.
[7] a) M. Chen, J. Wang, Z. Chai, C. You, A. Lei, Adv. Synth. Catal.
2012, 354, 341; b) M. Vellakkaran, M. M. S. Andappan, N. Kommu,
Eur. J. Org. Chem. 2012, 4694.
[8] L. Huang, J. Qi, X. Wu, K. Huang, H. Jiang, Org. Lett. 2013, 15,
Experimental Section
2330.
À
[9] Examples for Ar H bonds oxidative Heck Reactions: a) Y. Lu, D.-
General procedure for the palladium-catalyzed Heck-type reaction of
heterocycles and allylic alcohols: To a Schlenk tube were added heterocy-
cles (0.5 mmol), allylic alcohol (0.6 mmol), PdACTHNURGTNEUNG(OAc)2 (5 mol%) and
CH3COOH (2 mL) and were stirred overnight at the required reaction
temperature. After the reaction was finished, the solution was quenched
with aqueous NaHCO3 (10 mL) and extracted with ethyl acetate (3ꢁ
10 mL). The organic extracts were concentrated in vacuum, and the re-
sulting residue was purified by silica gel column chromatography using
light petroleum ether/ethyl acetate as eluent to afford the desired prod-
uct.
H. Wang, K. M. Engle, J.-Q. Yu, J. Am. Chem. Soc. 2010, 132, 5916;
b) A. Kubota, M. H. Emmert, M. S. Sanford, Org. Lett. 2012, 14,
1760; c) D.-H. Wang, K. M. Engle, B.-F. Shi, J.-Q. Yu, Science 2010,
327, 315; d) A. Vasseur, J. Muzart, J. L. Bras, Chem. Eur. J. 2011, 17,
12556; e) A. Vasseur, D. Harakat, J. Muzart, J. L. Bras, J. Org.
Chem. 2012, 77, 5751; f) M. Miyasaka, K. Hirano, T. Satoh, M.
Miura, J. Org. Chem. 2010, 75, 5421.
[10] Examples for decarboxylative Heck-type reactions: a) A. G. Myers,
D. Tanaka, M. R. Mannion, J. Am. Chem. Soc. 2002, 124, 11250;
b) D. Tanaka, S. P. Romeril, A. G. Myers, J. Am. Chem. Soc. 2005,
127, 10323; c) S.-L. Zhang, Y. Fu, R. Shang, Q.-X. Guo, L. Liu, J.
Am. Chem. Soc. 2010, 132, 638; d) Z. Fu, S. Huang, W. Su, M.
Hong, Org. Lett. 2010, 12, 4992; e) W. I. Dzik, P. P. Lange, L. J.
Gooßen, Chem. Sci. 2012, 3, 2671.
Acknowledgements
[11] a) A. Inoue, H. Shinokubo, K. Oshima, J. Am. Chem. Soc. 2003, 125,
1484; b) G.-W. Wang, T. Miao, Chem. Eur. J. 2011, 17, 5787; c) J. G.
Taylor, A. V. Moro, C. R. Correia, Eur. J. Org. Chem. 2011, 1403;
d) M.-K. Zhu, J.-F. Zhao, T.-P. Lop, Org. Lett. 2011, 13, 6308; e) F.-
The authors are grateful to the National Natural Science Foundation of
China (20932002 and 21172076), National Basic Research Program of
Chem. Eur. J. 2013, 19, 15462 – 15466
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
15465

H. Jiang et al.
X. Felpin, L. Nassar-Hardy, F. L. Callonnec, E. Fouquet, Tetrahedron
2011, 67, 2815.
[12] L. Huang, Q. Wang, J. Qi, X. Wu, K. Huang, H. Jiang, Chem. Sci.
2013, 4, 2665.
[14] a) X. Zhou, J. Luo, J. Liu, S. Peng, G.-J. Deng, Org. Lett. 2011, 13,
1432; b) X. Yu, X. Li, B. Wan, Org. Biomol. Chem. 2012, 10, 7479;
c) B. Liu, J. Li, F. Song, J. You, Chem. Eur. J. 2012, 18, 10830; d) F.-
L. Yang, X.-T. Ma, S.-K. Tian, Chem. Eur. J. 2012, 18, 1582.
[15] Y. Wen, L. Huang, H. Jiang, H. Chen, J. Org. Chem. 2012, 77, 2029.
[13] a) S.-D. Yang, C.-L. Sun, Z. Fang, B.-J. Li, Y.-Z. Li, Z.-J. Shi, Angew.
Chem. 2008, 120, 1495; Angew. Chem. Int. Ed. 2008, 47, 1473;
b) E. M. Beck, N. P. Grimster, R. Hatley, M. J. Gaunt, J. Am. Chem.
Soc. 2006, 128, 2528; c) N. P. Grimster, C. Gauntlett, C. R. A. God-
frey, M. J. Gaunt, Angew. Chem. 2005, 117, 3185; Angew. Chem. Int.
Ed. 2005, 44, 3125; d) A. Garcꢂa-Rubia, R. G. Arrayꢃs, J. C. Carre-
tero, Angew. Chem. 2009, 121, 6633; Angew. Chem. Int. Ed. 2009,
48, 6511; e) Z. Wang, K. Li, D. Zhao, J. Lan, J. You, Angew. Chem.
2011, 123, 5477; Angew. Chem. Int. Ed. 2011, 50, 5365; f) S. R. Kan-
dukuri, J. A. Schiffner, M. Oestreich, Angew. Chem. 2012, 124, 1291;
Angew. Chem. Int. Ed. 2012, 51, 1265; g) M. V. Leskinen, K.-T. Yip,
A. Valkonen, P. M. Pihko, J. Am. Chem. Soc. 2012, 134, 5750.
II
À
[16] Examples for quenching the C Pd bonds by protonolysis: a) L.
Zhao, X. Lu, Org. Lett. 2002, 4, 3903; b) S. Lin, X. Lu, Org. Lett.
2010, 12, 2536; c) Q. Peng, H. Yan, X. Zhang, Y.-D. Wu, J. Org.
Chem. 2012, 77, 7487.
[17] a) J. A. Keith, J. Oxgaard, W. A. Goddard, J. Am. Chem. Soc. 2006,
128, 3132; b) C. N. Cornell, M. S. Sigman, J. Am. Chem. Soc. 2005,
127, 2796; c) B. J. Anderson, J. A. Keith, M. S. Sigman, J. Am.
Chem. Soc. 2010, 132, 11872; d) T.-S. Mei, E. W. Werner, A. J.
Burckle, M. S. Sigman, J. Am. Chem. Soc. 2013, 135, 6830.
Received: July 27, 2013
Published online: October 21, 2013
15466
www.chemeurj.org
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 15462 – 15466