Formation of α-chalcogenyl acrylamides through unprecedented chalcogen-mediated metal-free oxyfunctionalization of ynamides with DMSO as an oxidant

Article abstract of DOI:10.1039/c5cc10517j

A novel chalcogen-mediated oxyfunctionalization mode of ynamides for the synthesis of α-chalcogenyl acrylamides has been developed. Independent of metal catalysts, external oxidants and additives, this mild process afforded a range of structurally diverse

Full text of DOI:10.1039/c5cc10517j

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Formation of αꢀChalcogenyl Acrylamides through
Unprecedented ChalcogenꢀMediated MetalꢀFree
Oxyfunctionalization of Ynamides with DMSO as
Oxidant
Cite this: DOI: 10.1039/x0xx00000x
Received 00th January 2012,
Accepted 00th January 2012
Hai Huang, Luning Tang, Qi Liu, Yang Xi, Guangke He* and Hongjun Zhu*
DOI: 10.1039/x0xx00000x
www.rsc.org/
onto the ketiminium intermediate 1 (Scheme 1, b). Further step to
develop a metalꢀfree or even catalystꢀfree oxyfunctionalization of
ynamides is of great necessities yet challenges. On the other hand,
chalcogen cations were widely used as electrophile sources.11 For
examples, chlorothiolation across alkynes represents an attractive
research topic in organic synthesis for synthesis of vinyl sulfides11bꢀc
(Scheme 1. c). Inspired by these reports and our interest in exploring
the metalꢀfree functionalization of ynamides,12 we envisioned the
possibility of the synthesis of acrylamides by chalcogenꢀmediated
oxidation of ynamides using external oxidant. Herein, we describe
the development of a novel metalꢀfree oxyfunctionalization mode of
ynamides by using DMSO as oxidant, which is an ideal and efficient
approach to αꢀchalcogenyl acrylamides (Scheme 1, d).
A
novel chalcogenꢀmediated oxyfunctionalization mode of
ynamides for the synthesis of αꢀchalcogenyl acrylamides has
been developed. Independent of metal catalysts, external
oxidants and additives, this mild process afforded a range of
structurally diverse αꢀchalcogenyl acrylamides, including αꢀ
selanyl acrylamides and αꢀtellanyl acrylamides. Interestingly,
diverse ynamides tolerated in this approach gave different
stereoselectivity.
The introduction of chalcogen groups into organic molecules
modifies their physical and chemical properties as well as biological
activities.1 Furthermore, the carbonꢀchalcogen bonds also have
widespread applications as versatile building blocks in organic
synthesis.2 Thus the generation of organochalcogenide compounds
has captured considerable attention and many methods have been
established for their synthesis.3 However, the development of new
efficient protocols for the synthesis of functionalized chalcogenꢀ
substituted compounds remains an indispensable task in organic
chemistry.
Acrylamide is a versatile component of many biologically active
compounds and nature products. A vast number of pharmaceuticals
containing these structural motifs are being used for therapeutic
purposes.4 Over the past decade, ynamides have been established as
the ultimate synthetic units because of their electronꢀrich and
relatively stable nature.5 And the oxyfunctionalization of ynamides
is an essential tool for the synthesis αꢀfunctionalized amides.6 And
acrylamides can also be generated by metalꢀcatalyzed intermolecular
oxidation of ynamides.7 Early in 2010, Davies’ group7a has reported
a goldꢀcatalyzed intermolecular oxidation of ynamides affording
acrylamide derivatives (Scheme 1, a). However, it was a major
technical hurdle to use a noble transitionꢀmetal catalyst in the
oxyfunctionalization of ynamides.8 More recently, to break through
this hurdle, Ye and coꢀworkers9 developed such oxidation
successfully by using Zn(OTf)2 as metal catalyst (Scheme 1, a).
Relatively more excellent work about generation of acrylamide from
ynamides was given by Skrydstrup’s group10 in 2011. In their study,
ynamides was activated by halogen electrophile as Lewis acid. A
high Zꢀselectivity was achieved after the intramolecular acetate shift
Scheme 1. Chalcogenꢀmediated oxidation of ynamides.
In the initial experiments, we selected yneoxazolidinone 1a and pꢀ
tolylsulfenylchloride 2a as the model substrates for the optimization.
To our delight, the reaction gave expected acrylamides 3a in total 44%
o
yield at 80 C for 1h, the mixture of Z and E isomers is obtained in
an almost 2:1 ratio (Table 1, entry 1). To further increase the yield of
3a, we carried out the reaction under different temperatures. The
reaction produced acrylamides 3a in total 89% yield with same Z:E
selectivity at room temperature. Reducing the loading of pꢀ
tolylsulfenylchloride 2a, the reaction gave poor yields and Z:E
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selectivity (Table 1, entries 4ꢀ5). And a similar amount of product 3a group on the orthoꢀposition of the aryl ring is wellꢀtolerated in the
was achieved with more 2a used (Table 1, entry 6 vs entry 3). reaction (Table 3, Eꢀ3ig). Other doubleꢀsubstituted arylsulfenyl
Extending the reaction time did not much change Z:E selectivity (for chlorides were also good substrates for this oxidation and afforded
details, see SI).13 In addition, it was found that the screening of base the corresponding (E)ꢀisomers Eꢀ3ih, Eꢀ3ii in 71ꢀ74% yields (Table
additives, such as K2CO3 and Et3N, could not further improve the 3, 3ihꢀ3ii).
reaction (Table 1, entries 7ꢀ8). This transformation gave poor results
no matter under oxygen or H2O condition, which further reveals that
DMSO probably plays a role of oxidant (Table 1, entries 9ꢀ10).
Table 2. Scope of Ynamides.a
Table 1. Optimization of the reaction conditions for 1a.a
O
O
O
Z/Eb Yield
Additives
O
N
Entry
Substrate
Product
N
Ar SCl
+
O
DMSO, N2, T, 1h
S
O
O
O
Ar
2a; Ar = p-MePh
n = 3, 1a
n = 4, 1b
n = 3, 3a
n = 4, 3b
n = 7,
79%
1a
1
2
3
2.1/1
3a
O
N
O
( )n-1
N
( )n
2.1/1
2.1/1
64%
O
73%
Total yield b
1c
3c
S
2a
n = 7,
Ar
Entry
T
Additives
Z/Eb
(equiv)
(%)
44
78
89
34
73
88
80
80
ꢀꢀ
O
O
1
2
3
4
5
2.0
2.0
2.0
1.2
1.5
3.0
2.0
2.0
80
50
rt
rt
rt
rt
rt
rt
rt
2.1/1
2.1/1
2.1/1
1.6/1
2.1/1
2.1/1
2.1/1
2.1/1
O
Ph
N
4
5
Ph
N
O
3d
3e
2.1/1
65%
1d
1e
S
Ar
O
O
O
O
78%
1.8/1
1.3/1
--
N
N
N
O
S
Ar
Ar
Bn
Bn
6
7
O
O
O
K2CO3
Et3N
O
71%
3f
1f
O
N
8
6
7
S
9c
10d
2.0
2.0
complex
1.6/1
Ph
Ph
O
rt
<30
O
O
a Reaction conditions: 1a (0.3 mmol), 2a and additives (2.0 equiv) in
DMSO (2.0 mL) under N2 condition at T for 1h. b Determined by 1H
NMR on the crude reaction mixture using 1,3,5ꢀtrimethylbenzene as
an internal standard. Under O2 (1 atm) atmosphere. 5.0 equiv of
H2O was added.
Z-3g: 65%c
Z-3h: 64%c
O
Ph
N
N
Z-3g
3h
1g
1h
O
S
Ph
Ar
O
O
c
d
O
O
O
N
4.6/1
N
9
S
Ar
With the optimum reaction conditions in hand, the scope and
generality of this reaction were explored by treating different
ynamides and pꢀtolylsulfenylchloride 2a to generate various αꢀthio
acrylamide products. The results showed in Table 2. Alkylꢀ
substituted yneoxazolidinones 1aꢀ1d could all have good yields
successfully under the reaction conditions, and the (Z)ꢀisomer was
formed as the major in all case (Table 2, entries 1ꢀ4). Ynamides 1eꢀ
1f containing chiral auxiliaries were also examined, and the results
show that both of them give good yields, but have lower Z/E
selectivity probably due to the increase of steric hindrance (Table 2,
entries 5ꢀ6). To our delight, a single product was observed on the
TLC monitoring in the reaction of 3ꢀ(3ꢀphenylbutꢀ1ꢀynꢀ1ꢀ
yl)oxazolidinꢀ2ꢀone 1g. The product was isolated in 65% yield and
the stereochemistry was confirmed to be (Z)ꢀisomer by singleꢀcrystal
Xꢀray diffraction.14 (Table 2, entry 7). Nꢀalkylnyl indole 1h was also
examined, and it could be transformed into the corresponding
product successfully. In the case of 1h, (E)ꢀisomer was isolated in 64%
yield (Table 2, entry 9). Furthermore, ynesulfonamides were all
successfully converted to the corresponding αꢀchalcogenyl
acrylamides, and both Nꢀtosyl and Nꢀmesityl substitution worked
well, for instance 1i and 1j. Interestingly, Eꢀstereoselectivity was
major isomer in the oxidation of ynesulfonamides (Table 1, entries
10ꢀ11). Additionally, the stereochemistry was confirmed by Xꢀray
analysis of products Zꢀ3e and Eꢀ3i.13
O
O
Ts
Ts
E-3i: 66%c
E-3j: 58%c
N
N
1/4.8
1/3.1
N
3i
3j
1i
1j
10
11
Bn
S
S
Bn
Ar
Ar
Ms
Bn
Ms
N
Bn
a The reaction was carried out with 1 (0.30 mmol) and 2a (2.0 equiv)
in DMSO (2.0 mL) at rt under N2 condition for 1 h. Z/E ratio was
determined by H NMR on the crude reaction mixture. The major
isomer was isolated.
b
1
c
Table 3. Scope of sulfenyl chlorides for oxidationa
O
Ts
Ts
N
N
Ar SCl
+
DMSO, N2, rt
Bn
S
Bn
2b-2i
Ar
1i
3
The scope of arenesulfenyl chlorides in this oxidation was next
investigated as shown in Table 3. Methyl, tertꢀbutyl, trifluoromethyl,
chloro, and bromo groups substituted in paraꢀposition of aryl ring
were compatible with the reaction and in all cases the (E)ꢀisomer
was formed as the major, and Eꢀisomers were isolated (Table 3, 3ibꢀ
3ie). Ynamides with groups on the metaꢀposition of the aryl ring,
such as F, generated the corresponding (E)ꢀisomer αꢀchalcogenyl
acrylamides in moderate yield (Table 3, 3if). Meanwhile, a bromo
a The reaction was carried out with 1i (0.30 mmol) and ArSCl (2.0
equiv) in DMSO (2.0 mL) at rt under N2 condition for 1 h; The
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1
by keteniminium forms A′ to increase their electrophilicity and
regioselectivity.17 A′ can be nucleophilically attacked by DMSO to
produce intermediate B,18 which undergoes a vinyligous E2ꢀtype
elimination9 to afford the corresponding αꢀthio acrylamides 2
(Scheme 5).
major Eꢀisomers was isolated; Z/E ratio was determined by H
NMR on the crude reaction mixture.
To demonstrate the synthetic potential of this strategy, 1i (5.0
mmol) was employed in the reaction under the optimal conditions,
which could be scaled up to 5.0 mmol without a significant decrease
in the yield (see Scheme 2). For example, a 63% yield of product Eꢀ
3i was obtained when 1i (5 mmol) was employed in a reaction with
pꢀtolylsulfenylchloride 2a (Scheme 2).
Scheme 2. Largeꢀscale experiments.
Next, to further explore the scope and application of the method,
we attempted to make αꢀselanyl acrylamides and αꢀtellanyl
acrylamides with the same approach. It was found that the reaction
of ynesulfonamides 1i with phenylselanylchloride excellently
proceeded to generate product 4ia with a 1:4.2 ratio of Z/E isomer,
and (E)ꢀNꢀbenzylꢀ2ꢀ(phenylselanyl)ꢀNꢀtosylhexꢀ2ꢀenamide Eꢀ4ia
was isolated in 56% yield (Scheme 3, a). Furthermore, (E)ꢀNꢀbenzylꢀ
2ꢀ(phenyltellanyl)ꢀNꢀtosylhexꢀ2ꢀenamide Eꢀ5ia could also be
afforded in 41% yield via phenyltellanylbromideꢀmediated oxidation
Scheme 5. Proposed mechanism for the oxidation.
Conclusions
In summary, we have developed the novel and efficient protocols
for the synthesis of various αꢀchalcogenyl acrylamides based on the
chalcogenꢀmediated oxidation of ynamides. To the best of our
knowledge, this method not only systemically reported a metalꢀfree
oxyfunctionalization of ynamides to acrylamides, but also tolerated a
wide range of functional groups on the ynamides component under
mild condition. Chalcogen electrophile reagents, including ArSCl,
ArSeCl and ArTeBr, were able to promote this novel oxidation.
Further studies on other electrophileꢀmediated functionalization of
ynamides are being conducted in our laboratory and will be reported
in due course.
of ynmaides (Scheme 3, b).15
O
Ts
N
Ts
PhSeCl
Se Bn
N
Bn
(a)
DMSO, N2, rt
1i
4ia
E-
4ia, Yield: 56%, Z/E = 1:4.2
O
1) Br2, DCE, N2, 0 o
30 min
C
Ts
N
Te Bn
(b)
PhTeTePh
2) 1i, DMSO, N2, rt
The authors greatly acknowledge the financial support in part by
Provincal Natural Science Foundation of Jiangsu, China (NO.
BK20140937), Postgraduate Innovation Fund of Jiangsu Province
(2015, KYLX15_0797).
5ia
E-5ia
, Yield: 41%, Z/E = 1:2.1
Scheme 3. Synthesis of αꢀselanyl/tellanyl acrylamides.
Notes and references
Finally, to understand the mechanism of the reaction, GCꢀMS
analysis of the reaction of 1i was carried out and the dimethyl sulfide
was detected by GCꢀMS (MS = 62.1) analysis, which indicates that
DMSO plays a role of oxidant (Scheme 4, I). We also confirmed that
in the presence of radical scavengers like TEMPO and BHT, the
chalcogenꢀmediated oxidation proceeded smoothly to form αꢀ
chalcogenyl acrylamides Eꢀ3i in 60ꢀ63% yields, which strongly rules
out a radical process (Scheme 4, II).
Department of Applied Chemistry, College of Sciences, Nanjing Tech
University, Nanjing 211816, People’s Republic of China, E-mail:
hegk@njtech.edu.cn; zhuhj@njtech.edu.cn
†
Electronic Supplementary Information (ESI) available: [Experimental
details, spectral data of all new compounds and crystal structure data for
3e 3g and 3i in CIF format.]. See DOI: 10.1039/c000000x/
Z
ꢀ
,
Z
ꢀ
Eꢀ
[1] a) A. L. Wolfe, K. K. Duncan, N. K. Parelkar, S. J. Weir, G. A. Vielhauer,
D. L. Boger, J. Med. Chem. 2012, 55, 5878; b) R. D. Taylor, M. MacCoss,
A. D. G. Lawson, J. Med. Chem. 2014, 57, 5845; c) S. Jeschke, A.ꢀC.
Gentschev, H.ꢀD. Wiemhöfer, Chem. Commun. 2013, 49, 1190; d) G.
Sartori, J. S. S. Neto, A. P. Pesarico, D. F. Back, C. W. Nogueira, G. Zeni,
Org. Biomol. Chem. 2013, 11, 1199; e) L. A. Ba, M. Döring, V. Jamier, C.
Jacob, Org. Biomol. Chem. 2010, 8, 4203; f) V. Jamier, L. A. Ba, C.
Jacob, Chem. -Eur. J. 2010, 16, 10920.
[2] a) T. Wirth, Tetrahedron 1999, 55, 1; b) T. Wirth, Angew. Chem. 2000,
112, 3890; Angew. Chem. Int. Ed. 2000, 39, 3740; c) A. L. Braga, D. S.
Lüdtke, F. Vargas, R. C. Braga, Synlett 2006, 1453; d) A. L. Braga, D. S.
Lüdtke, F. Vargas, Curr. Org. Chem. 2006, 10, 1921; e) D. M.
Freudendahl, S. A. Shahzad, T. Wirth, Eur. J. Org. Chem. 2009, 1649; f)
K. Itami, S. Higashi, M. Mineno, J.ꢀi. Yoshida, Org. Lett. 2005, 7, 1219;
Scheme 4. Experiments for mechanistic study.
On the basis of previous reports and results above, we propose the
following plausible mechanisms for the formation of αꢀchalcogenyl
acrylamides. In the presence of arenesulfenyl chlorides as a weak
Lewis acid, 1 produces the thiirenium intermediate A16 characterized
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g) The Chemistry of Organic Selenium and Tellurium Compounds, Volme [12] a) H. Huang, G. He, X. Zhu, X. Jin, S. Qiu, H. Zhu, Eur. J. Org. Chem.
4; Z. Rappoport, Eds; John Wiley & Sons, 2014.
2014, 7174; b) H. Huang, X. Zhu, G. He, Q. Liu, J. Fan, H. Zhu, Org.
Lett. 2015, 17, 2510.
[3] a) M. Pattarozzi, C. Zonta, Q. B. Broxterman, B. Kaptein, R. De Zorzi, L.
Randaccio, P. Scrimin, G. Licini, Org. Lett. 2007, 9, 2365; b) Y. Takeda, [13] See the Supporting Information for details.
S. Okumura, S. Tone, I. Sasaki, S. Minakata, Org. Lett. 2012, 14, 4874; c) [14] Crystal data for Zꢀ2g: C20H19NO3S, M = 353.42, triclinic, space group
C. R. McElroy, F. Aricò, F. Benetollo, P. Tundo, Pure Appl. Chem. 2012,
84, 707.
Pꢀ1, final R indices [ I>2σ(I)]: R1 = 0.0417, wR2 = 0.1127, R indices (all
data): R1 = 0.0572, wR2 = 0.1248, a = 7.326(5) Å, b = 10.134(7) Å, c =
12.489(8) Å, α = 80.774(11)°, β = 82.540(12)°, γ = 77.770(11)°, V =
890.0(10) Å3, T = 296 K, Z = 2, reflection measured/independent:
4938/3122 (Rint = 0.021), number of observations [I>2σ(I)]: 2417,
parameters: 228. CCDCꢀ1422307 contains the supplementary
crystallographic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
[4] a) J. A. Nieman, J. E. Coleman, D. J. Wallace, E. Piers, L. Y. Lim, M.
Roberge, R. J. Anderson, J. Nat. Prod. 2003, 66, 183; b) G. Giannini, M.
Marzi, R. Pezzi, T. Brunetti, G. Battistuzzi, M. Di Marzo, W. Cabri, L.
Vesci, C. Pisano, Bioorg. Med. Chem. Lett. 2009, 19, 2346; c) B. J. Leslie,
C. R. Holaday, T. Nguyen, P. J. Hergenrother, J. Med. Chem. 2010, 53,
3964; d) C. Marrano, P. de Macedo, J. W. Keillor, Bioorg. Med. Chem.
2001, 9, 1923; e) Y. F. Shealy, J. M. Riordan, J. L. Frye, L. Simpsonꢀ
Herren, B. P. Sani, D. L. Hill, J. Med. Chem. 2003, 46, 1931.
[15] Due to unstable, phenyltellanylbromide was used as a crude product.
Preparation of the phenyltelluryl bromide solution: Bromine (0.6 mmol)
was added to a flask containing diphenyl ditelluride (0.6 mmol) in 1,2ꢀ
dichloroethane (1.0 mL) at 0 °C. The reaction mixture was stirred for 15
min at this temperature.
[5] For select works about ynamides: a) Y. Yang, L. Wang, J. Zhang, Y. Jin,
G. Zhu, Chem. Commun. 2014, 50, 2347; b) C. Shu, Y. Wang, B. Zhou,
X. Li, Y. Ping, X. Lu, L. Ye, J. Am. Chem. Soc. 2015, 137, 9567; c) X.
Chen, D. Shen, Q. Wang, Y. Yang, B. Yu, Chem. Commun. 2015, 51,
13957; d) A. D. Gillie, R. J. Reddy, P. W. Davies, Adv. Synth. Catal. [16] a) G. H. Schmid, A. Modro, F. Lenz, D. G. Garratt, K. Yates, J. Org.
2016, 358, 226; e) N. Zheng, Y. Chang, L. Zhang, J. Gong, Z. Yang,
Chem. Asian J. 2016, 11, 371; f) V. Dwivedi, M. H. Babu, R. Kant, M. S.
Reddy, Chem. Commun. 2015, 51, 14996; g) S. Xu, J. Liu, D. Hu, X. Bi,
Chem. 1976, 41, 2331; b) C. Viglianisi, L. Becucci, C. Faggi, S.
Piantini, P. Procacci, S. Menichetti, J. Org. Chem. 2013, 78, 3496; c) L.
Benati, C. Montevecchi, P. Spagnolo, Tetrahedron 1993, 49, 5365.
Green Chem. 2015, 17, 84; h) H. Huang, L. Tang, X. Han, G. He, Y. Xi, [17] a) K. A. DeKorver, H. Li, A. G. Lohse, R. Hayashi, Z. Lu, Y. Zhang, R.
H. Zhu, Chem. Commun. 2016, DOI: 10.1039/c6cc00370b.
P. Hsung, Chem. Rev. 2010, 110, 5064; b) G. Evano, A. Coste, K.
Jouvin, Angew. Chem. 2010, 122, 2902; Angew. Chem. Int. Ed. 2010,
49, 2840; c) X. N. Wang, H. S. Yeom, L. C. Fang, S. He, Z. X. Ma, B.
L. Kedrowski, R. P. Hsung, Acc. Chem. Res. 2014, 47, 560.
[6] a) K. Murakami, J. Imoto, H. Matsubara, S. Yoshida, H. Yorimitsu, K.
Oshima, Chem. Eur. J. 2013, 19, 5625; b) C. Cheng, S. Liu, G .Zhu, Org.
Lett. 2015, 17, 1581; c) M. D. Santos, P. W. Davies, Chem. Commun.
2014, 50, 6001; d) F. Pan, S. Liu, C. Shu, R. Lin, Y. Yu, J. Zhou, L. Ye, [18] a) T. Chikugo, Y. Yauchi, M. Ide, T. Iwasawa, Tetrahedron 2014
,
Chem. Commun. 2014, 50, 10726; e) N. Ghosh, S. Nayak, A. K. Sahoo,
Chem. Eur. J. 2013, 19, 9428; f) A. Mukherjee, R. B. Dateer, R.
Chaudhuri, S. Bhunia, S. N. Karad, R. Liu, J. Am. Chem. Soc. 2011, 133,
15372; g) C. Shen, L. Li, W. Zhang, S. Liu, C. Shu, Y. Xie, Y. Yu, L. Ye,
J. Org. Chem. 2014, 79, 9313; h) K. Wang, R. Ran, S. Xiu, C. Li, Org.
Lett. 2013, 15, 2374; i) L. Yang, K. Wang, C. Li, Eur. J. Org. Chem.
2013, 2775.
70, 3988; b) Y. Ashikari, A. Shimizu, T. Nokami, J. Yoshida, J. Am.
Chem. Soc 2013 135, 16070; c) B. Peng, X. Huang, L. Xie, N.
Maulide, Angew. Chem. 2014 126, 8862; Angew. Chem. Int. Ed.
2014 53, 8718.
.
,
,
,
[7] a) P. W. Davies, A. Cremonesi, N. Martin, Chem. Commun. 2011, 47, 379.
b) K. C. M. Kurtz, R. P. Hsung, Y. Zhang, Org. Lett. 2006, 8, 231; c) R.
P. Hsung, C. A. Zificsak, L. Wei, C. J. Douglas, H. Xiong, J. A. Mulder,
Org. Lett. 1999, 1, 1237;
[8] As described in the paper: L. Li, B. Zhou, Y. Wang, C. Shu, Y. Pan, X.
Lu, L. Ye, Angew. Chem. 2015, 127, 8363; Angew. Chem. Int. Ed. 2015,
54, 8245.
[9] F. Pan, C. Shu, Y. Ping, Y. Pan, P. Ruan, Q. Fei, L. Ye, J. Org. Chem.
2015, 80, 10009.
[10] S. Kramer, S. D. Friis, Z. Xin, Y. Odabachian, T. Skrydstrup, Org. Lett.
2011, 13, 1750;
[11] a) A. Monleón, G. Blay, L. R. Domingo, M. C. Muñoz, J. R. Pedro, Eur.
J. Org. Chem. 2015, 1020. b) L. Zhong, P. R. Savoie, A. S. Filatov, J. T.
Welch, Angew. Chem. 2014, 126, 536; Angew. Chem. Int. Ed. 2014, 53,
526; c) M. Iwasaki, T. Fujii, A. Yamamoto, K. Nakajima, Y. Nishihara,
Chem. Asian J. 2014, 9, 58; d) G. Capozzi, C. Caristi, V. Lucchini, G.
Modena, J. Chem. Soc. Perkin Trans. 1 1982, 2197; e) G. Capozzi, G.
Romeo, V. Lucchini, G. Modena, J. Chem. Soc. Perkin Trans. 1 1983,
831.
4 | J. Name., 2014, 00, 1-3
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