Ester-directed selective olefination of acrylates by rhodium catalysis

Article abstract of DOI:10.1002/adsc.201300944

Ester-directed olefination of acrylates via rhodium(III)-catalysis was developed. Various alkenes were reacted with acrylates to give the desired products in high stereoselectivity. Mechanistic investigations revealed that ester-directed C-H bond activati

Full text of DOI:10.1002/adsc.201300944

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DOI: 10.1002/adsc.201300944
Ester-Directed Selective Olefination of Acrylates by Rhodium
Catalysis
Ruokun Feng,a Wenlong Yu,a Kai Wang,a Zhanxiang Liu,a,* and Yuhong Zhanga,b,*
a
Department of Chemistry, ZJU-NHU United R&D Center, Zhejiang University, Hangzhou 310027, Peopleꢀs Republic of
China
Fax : (+86)-571-8795-3244; e-mail: liuzhanx@zju.edu.cn or yhzhang@zju.edu.cn
State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, Peopleꢀs Republic of China
b
Received: November 24, 2013; Revised: January 19, 2014; Published online: May 6, 2014
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201300944.
Abstract: Ester-directed olefination of acrylates via
rhodium(III)-catalysis was developed. Various alk-
enes were reacted with acrylates to give the desired
may result in a diverse range of 1,3-diene architec-
tures.
ACHTUNGTRENNUNG
G
For our initial investigation, ethyl 2-phenylacrylate
was employed as a test substrate for the olefination
reaction due to the ubiquity of acrylates in synthetic
organic chemistry and ease of their modification. The
desired product 3aa was obtained in 39% yield when
ethyl 2-phenylacrylate 1a was used as substrate
(Table 1, entry 1). Further studies showed that ace-
tone was the better solvent for the reaction (Table 1,
entries 1–3). The addition of bases such as KOAc,
Na2CO3 was not effective in the reaction (Table 1, en-
tries 4 and 5). Notably, the addition of acetic acid was
found to improve the reaction significantly and the
products in high stereoselectivity. Mechanistic in-
À
vestigations revealed that ester-directed C H bond
activation was the key step to this reaction.
À
Keywords: C H bond activation; ester group di-
rected olefination; oxidative coupling; rhodium-cat-
alyzed olefination; substituted 1, 3-dienes
À
Transition metal-catalyzed C H activation has optimal amount of HOAc was 15 equiv. (Table 1, en-
emerged as an extensive method in organic synthesis, tries 6–10). The mixed solvent of acetone and acetic
and medicinal chemistry as it minimizes waste forma- acid may enhance the solubility of cupric acetate or
tion and prefunctionalization steps.[1] In particular, promote the formation of the active intermediate C
À
À
chelation-assisted C H functionalization has become Rh
N
a powerful method for its excellent regioselectivity rior (Table 1, entry 11). It is important to note that
and reactivity. A variety of functional groups have KPF6 could be employed as the additive to give the
À
been successfully used as directing groups in C H ac- desired product in 58% yield (Table 1, entry 12). No
tivation of arenes, such as amides,[2] amines,[3] reaction was observed in the absence of additives or
imines,[4] alcohol,[5] cyano,[6] pyridyl sulfoxide[7] and catalysts (Table 1, entries 13 and 14). Other catalysts
thioether.[8] The ester group is an important synthetic were investigated. [RuCl
2ACHTNUTRGNENG(U p-cymene)]2 was less effec-
intermediate in natural compounds and readily avail- tive for this reaction, and no desired product was
able in organic compounds.[9] However, the use of an achieved when PdCl
ester as directing group in the C H bond activation (Table 1, entries 15 and 16). It was observed that
(CH3CN)2 was used as catalyst
À
remained challenging, due to its poorly directed prop- Cu
G
[10,13]
À
erties in chelation-assisted C H functionalization.
CuACHTUNTGRENNUNG
In a pioneering study, Murai discovered the ester-di- 18). Lower and higher temperatures were both inferi-
rected ortho-alkylation of aromatic esters using ruthe- or for this reaction (Table 1, entries 19 and 20). Thus,
nium as an efficient catalyst.[10a] Later, an ester-direct- the optimal reaction conditions were [RhCp*Cl2]2
ed ortho-hydroxylation of aromatic esters via rutheni- (5.0 mol%),
AgSbF6
(20 mol%),
CuACHTUNGTRENNUNG(OAc)2
um catalysis was reported by Rao.[10e–h] Very recently, (2.0 equiv.), HOAc (15 equiv.) under nitrogen in ace-
Chang developed an ester-directed ortho-olefination tone (1.0 mL) at 1108C for 24 h.
of arene esters using rhodium as the catalyst.[10i] In-
This direct cross-coupling reaction exhibited high
spired by these works, we envisaged the possibility of stereoseletivity to give the (Z,E) diene isomer as the
À
an ester-directed C H olefination of acrylates, which major product [the ratio of (Z,E) and (E,E) isomers
is 96/4]. X-ray crystallography of 3aa further con-
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Ruokun Feng et al.
Table 1. Optimization of the reaction conditions.[a]
Entry
Catalyst
Additive
Oxidant
Solvent
Yield [%]
1
2
3
4
5
6
7
8
N
AgSbF6
AgSbF6
AgSbF6
AgSbF6
AgSbF6
AgSbF6
AgSbF6
AgSbF6
AgSbF6
AgSbF6
AgBF4
KPF6
Cu
Cu
Cu
Cu
Cu
Cu
Cu
Cu
Cu
Cu
Cu
Cu
N
DCE
1,4-dioxane
acetone
39
41
45
NR
NR
49
61
68
63
56
acetone/KOAc (1 equiv.)
acetone/Na2CO3 (1 equiv.)
acetone/HOAc (5 equiv.)
acetone/HOAc (10 equiv.)
acetone/HOAc (15 equiv.)
acetone/HOAc (20 equiv.)
acetone/HOAc (30 equiv.)
acetone/HOAc (15 equiv.)
acetone/HOAc (15 equiv.)
acetone/HOAc (15 equiv.)
acetone/HOAc (15 equiv.)
acetone/HOAc (15 equiv.)
acetone/HOAc (15 equiv.)
acetone/HOAc (15 equiv.)
acetone/HOAc (15 equiv.)
acetone/HOAc (15 equiv.)
acetone/HOAc (15 equiv.)
9
10
11
12
13
14
15
16
17
18
19
20
62
58
–
Cu
T
NR
NR
34
NR
56
AgSbF6
AgSbF6
AgSbF6
AgSbF6
AgSbF6
AgSbF6
AgSbF6
Cu
Cu
Cu
(p-cymene)]2
G
Cu(OH)2·CuCO3
Cu
Cu
Cu
42
59[b]
61[c]
[a]
Reaction conditions: 1a (88 mg, 0.5 mmol), 2a (138 mg, 1.0 mmol), catalyst (0.025 mmol), additive (0.1 mmol), oxidant
(1.0 mmol), solvent 1.0 mL, 1108C, 24 h, under N2.
Reaction temperature was 808C.
[b]
[c]
Reaction temperature was 1208C.
firmed the structure of the product (Figure 1).[11]
On the basis of the optimization studies, we evalu-
Thus, the Rh-catalyzed direct cross-coupling for the ated the scope of alkenes as shown in Table 2. Various
preparation of 1,4-diaryl-1,3-dienes, which are fea- substituted styrenes were suitable substrates to give
tured prominently in non-linear optical materials[12] the desired products in moderate to good yields. A
and were previously synthesized by Pd-, Rh- and Ru- broad range of useful functional groups, including
catalyzed coupling reactions,[13–17] has successfully methyl (Table 2, entries 2 and 6), fluoride (Table 2,
been developed.
entries 3 and 7), chloride (Table 2, entries 4 and 8),
bromide (Table 2, entries 5 and 9), and nitro group
(Table 2, entry 10), could be tolerated. Styrenes bear-
ing electron-donating substituents showed higher re-
activity than those with electron-withdrawing groups
(Table 2, entries 1–10). A significant steric effect was
observed. For example, meta-substituted styrenes
gave the corresponding products in lower yields com-
pared with para-substituted styrenes (Table 2, en-
tries 1–9), and a-methylstyrene 2k failed to afford the
products under the reaction conditions (Table 2,
entry 11). 2-Vinylnaphthalene participated in the re-
action smoothly to give the desired 1,3-dienes in 46%
yield (Table 2, entry 12). The compatibility of chloride
and bromide groups on the aromatic ring offers an
opportunity for subsequent cross-coupling for more
complex molecules. When electron-deficient alkenes
Figure 1. X-ray structures of 3aa.
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Ester-Directed Selective Olefination of Acrylates by Rhodium Catalysis
Table 2. Exploration of the scope of ethyl 2-phenylacrylate towards direct cross-coupling with various alkenes.[a]
Entry
1
Substrate 2
Product 3
Yield [%][b]
2b
2c
2d
2a
3ab (96:4)[c]
3ac (95:5)
3ad (94:6)
3aa (96:4)
73
2
3
4
78
58
68
5
6
7
8
9
2e
2f
2g
2h
2i
3ae (96:4)
3af (94:6)
3ag (94:6)
3ah (95:5)
3ai (93:7)
71
70
58
63
65
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Ruokun Feng et al.
Table 2. (Continued)
Entry
Substrate 2
Product 3
Yield [%][b]
10
11
2j
2k
2l
3aj (94:6)
41[d]
3ak
NR
46
12
13
3al (92:8)
2m
2n
3am (>99:1)
3an (95:5)
43
35
14
[a]
Reaction conditions: 1a (88 mg, 0.5 mmol), 2 (1.0 mmol), [RhCp*Cl2]2 (15 mg, 0.025 mmol), AgSbF6 (34 mg, 0.1 mmol),
Cu(OAc)2 (183 mg, 1.0 mmol), HOAc (450 mg, 7.5 mmol), acetone (1.0 mL), 1108C, 24 h, under N2.
Isolated yields of the (Z,E) and (E,E) isomers.
Ratio of (Z,E) and (E,E) isomers determined by H NMR.
Reaction temperature 1208C.
ACHTUNGTRENNUNG
[b]
[c]
[d]
1
such as ethyl acrylate and n-butyl acrylate were used,
It is interesting that no reaction was observed by
the corresponding desired cross-coupling products the use of a-methylstyrene as the substrate, demon-
were obtained (Table 2, entries 13 and 14). In these strating that the ester group played the key role in
cases, the homo-coupling product of acrylate was ob- the olefination [Scheme 2, Eq. (1)]. The isotopic ex-
served (3mm and 3nn). It is worthy of note that this change studies with ethyl 2-phenylacrylate 1a re-
cross-coupling reaction exhibited excellent stereose- vealed that Z-olefinic H/D exchange proceeded much
lectivity with nearly complete generation of Z/E iso- faster than the E-olefinic H/D exchange [Scheme 1,
mers.
Eq. (2)]. In the presence of 1-chloro-4-vinylbenzene
We next examined the reactivity of other 2-aryl- 2a, E-olefinic H/D exchange of 1a was not observed
ACHTUNGTRENNUNG
in moderate to good yields. The stereoselectivity of a directing group through coordination with Rh
G
À
the products was generally high. The electron-rich to form the intermediate of ortho C Rh
N
and electron-withdrawing substituents in the phenyl
Based on these experiments and precedent litera-
ring of the 2-arylacrylate could give the desired prod- ture,[10,13,15d,17] a plausible reaction mechanism was pro-
ucts in 51% to 65% yields (Table 3, entries 2–5). The posed as shown in Scheme 2. Anion exchange of
meta-substituted 2-phenylacrylate gave a lower yield [Cp*RhCl2]2 with AgSbF6 afforded the reactive
compared with the para-substitued one (Table 3, en- RhACTHNUGRTNEUNG(III) species A, which selectively activates the Z-
À
tries 2 and 6). The ortho-methyl-substituted ethyl 2- olefinic C H bond of ethyl 2-phenylacrylate to form
phenylacrylate gave a 46% yield which may be due to intermediate B. Subsequent insertion of B to the
the effect of steric hindrance (Table 3, entry 8). The alkene forms intermediate D, which undergoes b-hy-
ortho-, meta-chloride and 2,4-dichloride substituted dride elimination to generate the olefinated product
ethyl 2-phenylacrylate gave 66%, 68% and 71% and concomitantly release a Rh(I) species that is re-
yields, respectively (Table 3, entries 9, 7 and 10).
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Ester-Directed Selective Olefination of Acrylates by Rhodium Catalysis
Table 3. Exploration of the scope of 2-arylacrylate towards direct cross-coupling with 1-chloro-4-vinylbenzene.[a]
Entry
1
Substrate 1
Product 3
Yield [%][b]
1b
1c
1d
1e
3ba (93:7)[c]
3ca (94:6)
3da (98:2)
3ea (97:3)
53
2
3
4
65
51
52
5
6
7
8
1f
1g
1h
1i
3fa (96:4)
54
61
68
46
3ga (96:4)
3ha (95:5)
3ia (3ia/3i=3:1)
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Ruokun Feng et al.
Table 3. (Continued)
Entry
Substrate 1
Product 3
Yield [%][b]
9
1j
3ja (95:5)
3ka (97:3)
66
10
1k
71
[a]
Reaction conditions: 1 (0.5 mmol), 2a (138 mg, 1.0 mmol), [RhCp*Cl2]2 (15 mg, 0.025 mmol), AgSbF6 (34 mg, 0.1 mmol),
Cu(OAc)2 (183 mg, 1.0 mmol), HOAc (450 mg, 7.5 mmol), acetone (1.0 mL), 1108C, 24 h, under N2.
Isolated yields of the (Z,E) and (E,E) isomers.
Ratio of (Z,E) and (E,E) isomers determined by H NMR.
ACHTUNGTRENNUNG
[b]
[c]
1
Scheme 1. Mechanism study.
Scheme 2. Proposed reaction mechanism.
oxidized to the +3 oxidation state by the action of
a copper species.
Experimental Section
In summary, we have developed the ester-directed
RhACHTUNGTRENNUNG(III)-catalyzed olefination of acrylates. This proto- General Procedure
col provides an efficient access to the substituted 1,3-
butadienes. Various alkenes were reacted with acryl-
ates to give desired products in high stereoselectivity.
The ester group of acrylates was found to be impor-
A 25-mL sealed tube with a magnetic stir bar was charged
with [RhCp*Cl2]2 (15 mg, 0.025 mmol), AgSbF6 (34 mg,
0.1 mmol), CuACTHNUTRGNEUNG(OAc)2 (183 mg, 1.0 mmol), HOAc (450 mg,
7.5 mmol), 2-arylacrylate 1 (0.5 mmol), styrene or acrylate
(1.0 mmol) and acetone (1.0 mL). Then the tube was sealed
under nitrogen and heated to 1108C with stirring for 24 h.
After cooling down, the mixture was filtered through a plug
of Celite, and then the residue was washed with ethyl ace-
À
tant to improve the activation of vinylic C H bonds
through chelation. Further studies on the application
À
of ester-directed C H activation are currently ongo-
ing in our laboratory.
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Ester-Directed Selective Olefination of Acrylates by Rhodium Catalysis
tate (3ꢂ20 mL). Then saturated Na2CO3 (15 mL) was
added, and the organic layer was collected. The aqueous
phase was extracted with ethyl acetate (2ꢂ20 mL). The
combined organic phases were washed with brine (2ꢂ
20 mL), dried over anhydrous sodium sulfate, filtered and
concentrated. The residue was purified by flash column
chromatography with ethyl acetate (EA) and petroleum
ether (Pet) as eluent to afford the corresponding products.
78, 3688; f) Z. Liang, R. Feng, H. Yin, Y. Zhang, Org.
Lett. 2013, 15, 4544.
[4] a) T. Fukutani, N. Umeda, K. Hirano, T. Satoh, M.
Miura, Chem. Commun. 2009, 5141; b) K. Gao, N.
Yoshikai, J. Am. Chem. Soc. 2011, 133, 400; c) M. J.
Tredwell, M. Gulias, N. G. Bremeyer, C. C. C. Johans-
son, B. S. L. Collins, M. J. Gaunt, Angew. Chem. 2011,
123, 1108; Angew. Chem. Int. Ed. 2011, 50, 1076; d) L.
Ackermann, N. Hofmann, R. Vicente, Org. Lett. 2011,
13, 1875; e) D. A. Colby, A.-S. Tsai, R. G. Bergman,
J. A. Ellman, Acc. Chem. Res. 2012, 45, 814.
[5] Y. Lu, D.-H. Wang, K. M. Engle, J.-Q. Yu, J. Am.
Acknowledgements
Chem. Soc. 2010, 132, 5916.
[6] a) W. Li, Z. Xu, P. Sun, X. Jiang, M. Fang, Org. Lett.
2011, 13, 1286; b) W. Li, P. Sun, J. Org. Chem. 2012, 77,
8362; c) B. Du, X. Jiang, P. Sun, J. Org. Chem. 2013, 78,
2786.
Funding from Zhejiang Province (No. 2011C11097) and
NSFC (No. 21072169 and No.21272205) is highly acknowl-
edged. The work was also supported by the Program for
Zhejiang Leading Team of S&T Innovation.
[7] a) A. Garcꢄa-Rubia, R. G. Arrayꢅs, J. C. Carretero,
Angew. Chem. 2009, 121, 6633; Angew. Chem. Int. Ed.
2009, 48, 6511; b) A. Garcꢄa-Rubia, B. Urones, R. G.
Arrayꢅs, J. C. Carretero, Chem. Eur. J. 2010, 16, 9676;
c) J. A. Romero-Revilla, A. Garcꢄa-Rubia, R. G.
Arrayꢅs, M. ꢆ. Fernꢅndez-IbꢅÇez, J. C. Carretero, J.
Org. Chem. 2011, 76, 9525; d) H. Richter, S. Becken-
dorf, O. G. MancheÇo, Adv. Synth. Catal. 2011, 353,
295; e) M. Yu, Z. Liang, Y. Wang, Y. Zhang, J. Org.
Chem. 2011, 76, 4987.
[8] a) M. Yu, Y. Xie, C. Xie, Y. Zhang, Org. Lett. 2012, 14,
2164; b) J. Yao, M. Yu, Y. Zhang, Adv. Synth. Catal.
2012, 354, 3205.
[9] a) G. E. Veitch, K. L. Bridgwood, S. V. Ley, Org. Lett.
2008, 10, 3623; b) P. Cao, D. P. Raleigh, J. Am. Chem.
Soc. 2010, 132, 4052.
[10] a) M. Sonoda, F. Kakiuchi, A. Kamatani, N. Chatani, S.
Murai, Chem. Lett. 1996, 109; b) F. Kakiuchi, H.
Ohtaki, M. Sonoda, N. Chatani, S. Murai, Chem. Lett.
2001, 918; c) N. M. Neisius, B. Plietker, Angew. Chem.
2009, 121, 5863; Angew. Chem. Int. Ed. 2009, 48, 5752;
d) B. Xiao, Y. Fu, J. Xu, T.-J. Gong, J.-J. Dai, J. Yi, L.
Liu, J. Am. Chem. Soc. 2010, 132, 468; e) Y. Yang, Y.
Lin, Y. Rao, Org. Lett. 2012, 14, 2874; f) G. Shan, X.
Yang, L. Ma, Y. Rao, Angew. Chem. 2012, 124, 13247;
Angew. Chem. Int. Ed. 2012, 51, 13070; g) X. Sun, G.
Shan, Y. Sun, Y. Rao, Angew. Chem. 2013, 125, 4536;
Angew. Chem. Int. Ed. 2013, 52, 4440; h) G. Shan, X.
Han, Y. Lin, S. Yu, Y. Rao, Org. Biomol. Chem. 2013,
11, 2318; i) S. H. Park, J. Y. Kim, S. Chang, Org. Lett.
2011, 13, 2372.
[11] CCDC 959121 contains the supplementary crystallo-
graphic data for this paper (3aa). 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.
[12] For applications of polyenes in non-linear optics, see
the special issue: H. S. Nalwa, M. Hanack, G. Pawlow-
ski, M. K. Engel, Chem. Phys. 1999, 245, 17.
References
[1] For selected general reviews on transition metal-cata-
À
lyzed C H activation and its synthetic applications,
see: a) D. Alberico, M. E. Scott, M. Lautens, Chem.
Rev. 2007, 107, 174; b) X. Chen, K. M. Engle, D.-H.
Wang, J.-Q. Yu, Angew. Chem. 2009, 121, 5196; Angew.
Chem. Int. Ed. 2009, 48, 5094; c) L. Ackermann, R.
Vicente, A. R. Kapdi, Angew. Chem. 2009, 121, 9976;
Angew. Chem. Int. Ed. 2009, 48, 9792; d) T. W. Lyons,
M. S. Sanford, Chem. Rev. 2010, 110, 1147; e) R. Jazzar,
J. Hitce, A. Renaudat, J. Sofack-Kreutzer, O. Baudoin,
Chem. Eur. J. 2010, 16, 2654; f) C. S. Yeung, V. M.
Dong, Chem. Rev. 2011, 111, 1251; g) J. Magano, J. R.
Dunetz, Chem. Rev. 2011, 111, 2177.
[2] For examples, see: a) O. Daugulis, V. G. Zaitsev,
Angew. Chem. 2005, 117, 4114; Angew. Chem. Int. Ed.
2005, 44, 4046; b) B.-J. Li, S.-L. Tian, Z. Fang, Z.-J. Shi,
Angew. Chem. 2008, 120, 1131; Angew. Chem. Int. Ed.
2008, 47, 1115; c) M. Wasa, K. M. Engle, J.-Q. Yu, J.
Am. Chem. Soc. 2009, 131, 9886; d) T. Nishikata, A. R.
Abela, S. Huang, B. H. Lipshutz, J. Am. Chem. Soc.
2010, 132, 4978; e) X. Zhao, C. S. Yeung, V. M. Dong,
J. Am. Chem. Soc. 2010, 132, 5837; f) J. Wencel-Delord,
C. Nimphius, F. W. Patureau, F. Glorius, Angew. Chem.
2012, 124, 2290; Angew. Chem. Int. Ed. 2012, 51, 2247;
g) W. C. P. Tsang, N. Zheng, S. L. Buchwald, J. Am.
Chem. Soc. 2005, 127, 14560; h) T.-S. Mei, X. Wang, J.-
Q. Yu, J. Am. Chem. Soc. 2009, 131, 10806; i) D. R.
Stuart, M. Bertrand-Laperle, K. M. N. Burgess, K.
Fagnou, J. Am. Chem. Soc. 2008, 130, 16474; j) Q.
Chen, L. Ilies, E. Nakamura, J. Am. Chem. Soc. 2011,
133, 428; k) D.-D. Li, T.-T. Yuan, G.-W. Wang, J. Org.
Chem. 2012, 77, 3341; l) F. Pꢃron, C. Fossey, T. Cailly,
F. Fabis, Org. Lett. 2012, 14, 1827.
[3] For examples, see: a) G. Cai, Y. Fu, Y. Li, X. Wan, Z.
Shi, J. Am. Chem. Soc. 2007, 129, 7666; b) H. Li, G.-X.
Cai, Z.-J. Shi, Dalton Trans. 2010, 39, 10442; c) Z.
Liang, L. Ju, Y. Xie, L. Huang, Y. Zhang, Chem. Eur. J.
2012, 18, 15816; d) Z. Liang, J. Zhang, Z. Liu, K. Wang,
Y. Zhang, Tetrahedron 2013, 69, 6519; e) R. Feng, J.
Yao, Z. Liang, Z. Liu, Y. Zhang, J. Org. Chem. 2013,
[13] T. Besset, N. Kuhl, F. W. Patureau, F. Glorius, Chem.
Eur. J. 2011, 17, 7167.
[14] For representative examples: a) A. Torrado, B. Iglesias,
S. Lopez, A. R. de Lera, Tetrahedron 1995, 51, 2435;
b) B. H. Lipshutz, B. Ullman, C. Lindsley, S. Pecci, D. J.
Buzard, D. Dickson, J. Org. Chem. 1998, 63, 6092; c) B.
Adv. Synth. Catal. 2014, 356, 1501 – 1508
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
1507

COMMUNICATIONS
Ruokun Feng et al.
Dominguez, B. Iglesias, A. R. de Lera, Tetrahedron
1999, 55, 15071; d) F. Zeng, E. Negishi, Org. Lett. 2002,
4, 703; e) S. E. Denmark, S. A. Tymonko, J. Am. Chem.
Soc. 2005, 127, 8004.
2011, 2, 1822; e) H. Yu, W. Jin, C. Sun, J. Chen, W. Du,
S. He, Z. Yu, Angew. Chem. 2010, 122, 5928; Angew.
Chem. Int. Ed. 2010, 49, 5792; f) Y. Zhang, Z. Cui, Z.
Li, Z. Liu, Org. Lett. 2012, 14, 1838.
[15] a) Y. Hatamoto, S. Sakaguchi, Y. Ishii, Org. Lett. 2004,
6, 4623; b) Y.-H. Xu, J. Lu, T.-P. Loh, J. Am. Chem.
Soc. 2009, 131, 1372; c) Y.-H. Xu, W.-J. Wang, Z.-K.
Wen, J. J. Hartley, T.-P. Loh, Tetrahedron Lett. 2010, 51,
3504; d) Y.-H. Xu, Y. K. Chok, T.-P. Loh, Chem. Sci.
[16] a) G. Song, F. Wang, X. Li, Chem. Soc. Rev. 2012, 41,
3651; b) X. Shang, Z. Liu, Chem. Soc. Rev. 2013, 42,
3253.
[17] J. Zhang, T.-P. Loh, Chem. Commun. 2012, 48, 11232.
1508
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Adv. Synth. Catal. 2014, 356, 1501 – 1508