Cu(i)/Fe(III)-Catalyzed C-P cross-coupling of styrenes with H-phosphine oxides: A facile and selective synthesis of alkenylphosphine oxides and β-ketophosphonates

Article abstract of DOI:10.1039/c7ob00505a

Cu(i)/Fe(iii)-Catalyzed phosphorylation and oxyphosphorylation of styrenes with H-phosphonates which can be controlled by varying the reaction temperature are developed. This study offers a new and expedient strategy for the synthesis of useful alkenylphosphine oxides and β-ketophosphonates in satisfactory yields. Moreover, the transformation is proposed to proceed via a radical process and exhibits a broad substrate scope and good functional group tolerance.

Full text of DOI:10.1039/c7ob00505a

View Article Online
View Journal
Organic &
Biomolecular
Chemistry
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: J. Gu and C. Cai,
Org. Biomol. Chem., 2017, DOI: 10.1039/C7OB00505A.
This is an Accepted Manuscript, which has been through the
Volume 14 Number
1 7 January 2016 Pages 1–372
Royal Society of Chemistry peer review process and has been
accepted for publication.
Organic &
Biomolecular
Chemistry
www.rsc.org/obc
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
author guidelines.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the ethical guidelines, outlined
in our author and reviewer resource centre, still apply. In no
event shall the Royal Society of Chemistry be held responsible
for any errors or omissions in this Accepted Manuscript or any
consequences arising from the use of any information it contains.
ISSN 1477-0520
COMMUNICATION
Takeharu Haino et al.
Solvent-induced emission of organogels based on tris(phenylisoxazolyl)
benzene
rsc.li/obc

Please do not adjust margins
Organic & Biomolecular Chemistry
Page 1 of 5
View Article Online
DOI: 10.1039/C7OB00505A
Journal Name
ARTICLE
Cu(I)/Fe(III)-Catalyzed C−P Cross-Coupling of Styrenes with H-
Phosphine Oxides: A Facile and Selective Synthesis of
Alkenylphosphine Oxides and β-Ketophosphonates
Received 00th January 20xx,
Accepted 00th January 20xx
Jian Gu,a Chun Cai* a
DOI: 10.1039/x0xx00000x
Cu(I)/Fe(III)-catalyzed phosphorylation and oxyphosphorylation of styrenes with H-phosphonates which can be controlled
by varying the reaction temperature are developed. This study offers a new and expedient strategy for the synthesis of
useful alkenylphosphine oxides and β-ketophosphonates in satisfactory yields. Moreover, the transformation is proposed
www.rsc.org/
to proceed via
a radical process and exhibits a broad substrate scope and good functional group tolerance.
Introduction
reported the synthesis of vinylphosphonates and phosphine
oxides via silver-catalyzed phosphorylation of styrenes with
the aid of TEMPO (2,2,6,6-Tetramethyl-1-piperidinyloxy) which
can help them get the vinylphosphonates instead of the
The construction of carbon–phosphorus bond is highly
important in organic synthesis, since organophosphorus
compounds are quite useful in biology, and material sciences.[1]
usually addition product (Scheme 1A, c) [6]
.
Among
them,
alkenylphosphine
oxides
and
β-
ketophosphonates are extremely useful classes of
phosphorous-containing organic compounds, owing to their
bioactivity and wide-ranging applications in various
synthetically useful transformations.[2] As a result of their
importance, wide interest has been generated in the
development of new strategies for their preparation. For the
synthesis of β-ketophosphonates, the acylation of
alkylphosphonates under basic conditions, the hydration of
alkynylphosphonates, the oxyphosphorylation of alkenes and
alkynes, and oxyphosphorylation of alkynes under different
bimetallic synergistically catalyzed aerobic oxidative conditions
have been mostly used.[3] And for the synthesis of
alkenylphosphine oxides, there are two main strategies
particularly noteworthy due to their overall efficiency and
selectivity: the phosphorylation of alkynes and functionalized
alkenes. Transition-metals such as Cu, Ni/Zn, Ag, Pd, and Mn-
catalyzed reactions of 1-bromo- and 1,1-dibromo-1-alkenes,
vinylboronate esters, vinylcarboxylic acids, and nitroalkenes
with dialkyl phosphites, triethyl phosphite, and diaryl
phosphine oxides have been reported to construct Csp2–P
bonds (Scheme 1A, a).[4] Transition metals such as Pd, Pt, Rh,
Zr, Mo, Cu and Ni catalysts were employed for the direct
phosphorylation of alkynes (Scheme 1A, b).[5] Recently, Tan
Scheme 1：Strategies for alkenyl Csp2–P bond formation.
As we know, the product selectivity controlled by
modification of the reaction conditions represents a significant
challenge in organic synthesis.[7] In particular, selective
catalysis that leads to different products from the same
starting materials is a powerful tool for divergent synthesis.[8]
Consequently, on the basis of the above excellent works, we
endeavoured to develop effective catalytic processes that
exploit selective and controllable way in this C−P bond forming
a.Chemical Engineering College, Nanjing University of Science and Technology,
200 Xiao Ling Wei, Nanjing 210094, People’s Republic of China.
Email: c.cai@njust.edu.cn.
† Electronic Supplementary Information (ESI) available: Experimental procedures
and characterization data for all products. See DOI: 10.1039/x0xx00000x
reaction between styrenes and H‑phosphonates. To our
delight, when we optimal the reaction conditions, we found
the main product can be controlled by varying the reaction
temperature, so that we can selective synthesis
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
Please do not adjust margins

Please do not adjust margins
Organic & Biomolecular Chemistry
Page 2 of 5
ARTICLE
Journal Name
β‑ketophosphonates by 8−9). When DTBP was replaced by TBHP (tert-Butyl
alkenylphosphine oxides and
controlling the temperature. We describe herein our hydroperoxide) or H2O2, the signifiDcaOnI:t10.1y0ie39ld/C7OdeB0cr0e5a05sAe
View Article Online
successful environmentally benign Cu(I)/Fe(III) catalysts system suggested that DTBP was crucial for this reaction.
A
with DTBP (Di-tert-butyl peroxide) as the oxidant, which can subsequent survey on the role of solvents revealed that DMSO
construct the Csp2-P bond directly from styrenes and H- (Dimethyl sulfoxide) was the optimal candidate (entries 10
o
phosphonates without TEMPO and form Csp3-P bond in a −12). Elevating the reaction temperature from 70 C to 110 oC,
different reaction temperature. ( Scheme 1B )
the optimal yields for 3aa and 4aa seperately were achieved at
o
o
110 C and 90 C (entries 5, 13−15). When the temperature
was 90 oC, the main product was 4aa and gave an approximate
1:3 mixture of 3aa and 4aa respectively. Finally, control
experiments showed that both catalysts and DTBP were
essential prerequisites for this reaction (entries 16 −19). Thus,
the optimal conditions for 3aa constitute a combination of
FeCl3 (20 mol %) and CuCl (10 mol %) in DMSO with TBP as
oxidant, NEt3 as base under Ar atmosphere for 15 h at 110 °C.
And when the temperature changed to 90 oC, the reaction
Results and discussion
We started our study by investigating the reaction
between styrene 1a and H-diethyl phosphonate 2a to generate
desired alkenylphosphine oxides 3aa and β-ketophosphonate
4aa (Table 1). First, a variety of transition-metal salts were
investigated, with the finding that CuCl and FeCl3 was the
optimal choice for the reaction (entries 1−7). As the next
optimization step, we performed an oxidant screening (entries
condition was optimal for 4aa
.
Table 1. Optimization of the Reaction Conditions a
Entry
Catalyst
Cocatalyst
Oxidant
Solvent
T(oC)
Yield of
3aa(%)b
Yield of
4aa(%)b
1
CuCl
CuCl
CuCl
Cu(OTf)2
CuCl
Cu2O
CuI
FeSO4
Fe(NO3)3
Fe(OTf)3
FeCl3
FeCl3
FeCl3
FeCl3
FeCl3
FeCl3
FeCl3
FeCl3
FeCl3
FeCl3
FeCl3
FeCl3
--
DTBP
DTBP
DTBP
DTBP
DTBP
DTBP
DTBP
TBHP
H2O2
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMF
110
110
110
110
110
110
110
110
110
110
110
110
70
--
--
--
--
--
--
--
--
--
--
--
--
--
36
61
47
--
--
--
--
2
--
3
--
4
45
78
33
--
5
6
7
8
CuCl
CuCl
CuCl
CuCl
CuCl
CuCl
CuCl
CuCl
CuCl
--
29
--
9
10
11
12
13
14
15
16
17
18
19
DTBP
DTBP
DTBP
DTBP
DTBP
DTBP
DTBP
DTBP
--
68
--
NMP
toluene
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
--
11
19
30
--
90
100
110
110
110
110
FeCl3
FeCl3
--
22
--
CuCl
--
DTBP
--
a) Reaction conditions: 1a (0.5 mmol), 2a (2 mmol), catalyst (10 mol%), cocatalyst (20 mol%), base (0.5 mmol), solvent (2 mL), oxidant (1
mmol), 15 h, under Ar atmosphere. b) Isolated yield. DMF is N,N’-Dimethylformamide. NMP is N-methyl-2-pyrrolidone.
With these optimized conditions in hand, we next Styrene derivatives with electron-donating substituents at the
examined the scope of the phosphorylation of alkenyls with H- phenyl ring afforded the desired alkenylphosphine oxides in
phosphonates for the synthesis of alkenylphosphine oxides 63−82% yield (3ba
(Table 2). Styrene derivatives in reaction with 2a were electron-withdrawing substituents at the phenyl ring provided
examined first. The reaction worked very well for a range of the desired alkenylphosphine oxides in 63−72% yield (3fa 3ia).
-3ea), whereas styrene derivatives bearing
-
alkenyls with various substituents at the phenyl ring, and the On the whole, the electron-donating substituted alkenyls
products were isolated in yields ranging from 63% to 82%. showed superior reaction efficiency to that of the electron-
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 3 of 5
Organic & Biomolecular Chemistry
Please do not adjust margins
Journal Name
withdrawing ones. In addition to alkyl and alkoxy groups, halo- hindered
ARTICLE
β
-methylstyrene was also suitable for
View Article Otnhlinise
DOI: 10.1039/C7OB00505A
substituted alkenyls were compatible with the standard transformation (4ma). In addition, the reaction was also
conditions (3ga-3ia). The halo- substituted alkenylphosphine extended to other electron-rich heteroaromatic and other
oxides were beneficial for further functionalization. Sterically phosphonates in moderate yield. This phosphorylation of
hindered α-methylstyrene was also suitable for this styrene with H-phosphonates could also be extended to the
transformation (3ja). Moreover, the arene ring is not limited to corresponding β-ketophosphonates (4ab
benzene rings. Heteroaromatic alkenyls could also be used as other phosphonates as the substrates.
suitable substrates, thus providing the corresponding desired
−4ad) when we used
Table 3. Substrate Scope of the oxyphosphorylation of Alkenyls with
H-Phosphonates for the synthesis of β‑Ketophosphonatesa
products in 32−78% yield (3ka
styrene with H-phosphonates could also be extended to the
corresponding alkenylphosphine oxides (3ab 3ad) when we
-3la). This phosphorylation of
−
used other phosphonates as the substrates. In addition to H-
phosphonates, we found that diphenylphosphine oxide was
applicable under the standard conditions as well and produced
the desired products 3af in a reasonable yield. The wide scope
of both the alkenyls and phosphonate partners illustrates the
good functional group tolerance and potential applications of
this method.
Table 2. Substrate Scope of the Phosphorylation of Alkenyls with H-
Phosphonates for the Synthesis of Vinylphosphonates a
a Reaction conditions: 1 (0.5 mmol), 2 (2 mmol), CuCl(10 mol %), FeCl3(20
mol %), Et3N (0.5 mmol), DTBP(1 mmol), DMSO (2 mL), 90 °C, 15 h, Ar,
all isolated yields.
To gain some insight into the mechanism for the Cu/Fe-
cocatalyzed oxidative cross-coupling of alkenyls with H-
phosphonates, control experiments were carried out (Scheme
2). No target product was observed by the addition of TEMPO
or BHT (butylated hydroxytoluene) as a radical inhibitor,
indicating that a radial pathway might be involved in the
process.(Scheme 2, a) No reaction occurred when only β-
ketophosphonates, alkenylphosphine oxides or styrene was
employed to the standard reaction conditions under 110oC or
90oC, suggesting that the initial oxyphosphorylation or
phosphorylation and styrene radical might not be involved in
the reaction mechanism. (Scheme 2, b, c and d) The different
temperature may be related to the boiling point of water, so
we conducted an experiment with dry DMSO. The proportion
of 4aa decreased significantly when dry DMSO was used,
indicating that H2O might be involved in the production of β-
ketophosphonates.(Scheme 2, e)
a Reaction conditions: 1 (0.5 mmol), 2 (2 mmol), CuCl(10 mol %), FeCl3(20
mol %), Et3N (0.5 mmol), DTBP(1 mmol), DMSO (2 mL), 110 °C, 15 h, Ar,
all isolated yields.
Subsequently we tested the application of the developed
Cu/Fe catalytic system towards the synthesis of different β-
ketophosphonates. When reactions performed at 90oC, the
coupling between styrene 1a and H-diethyl phosphonate 2a
resulted in a 1:3 mixture of the phosphorylation product 3aa
and 4aa. The selectivity of the coupling process was switched
in favor of the synthesis of β-ketophosphonates. Styrene
derivatives with electron-donating substituents or electron-
withdrawing substituents at the phenyl ring all gave the
Although the mechanistic details of this transformation
are not clear at the moment, on the basis of the above results
and previous reports, a plausible mechanism for the present
process can be proposed as shown in Scheme 3.[9,1i,3d]
desired products in satisfactory yields (4ba-4ia). Sterically
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
Organic & Biomolecular Chemistry
Page 4 of 5
ARTICLE
Journal Name
Phosphonyl radical
6 is generated from dialkyl phosphonate by exposure to ultraviolet light. Mass spectra are taken on a Thermo
View Article Online
cation radical
5
which is formed through single-electron Scientific ISQ LT GC-MS instrument in theDeOleI:c1t0ro.1n03i9o/nCi7zOatBi0o0n50(E5IA)
transfer from iron(II) species to HP(=O)(OR)2 in the presence of mode. H NMR, 13C NMR and 31P NMR spectra are recorded on an
1
TBP. Subsequently, addition of the phosphonyl radical
6 to the AVANCE 500 Bruker spectrometer operating at 500 MHz, 125 MHz
double bond of alkenyls produces the alkyl radical
7
7
. When the and 202 MHz in CDCl3, respectively, and chemical shifts are reported
is believed in ppm. High-resolution mass spectra data were obtained on Agilent
reaction temperature is 110oC, the formed radical
to undergo direct oxidation by deprotonation to release the mass spectrometer using ESI-TOF (electrospray ionization-time of
final product. Meanwhile, the CuCl was regenerated to flight).
continue the catalytic cycle. When the reaction temperature is
Synthesis of alkenylphosphine oxides from Alkenyls and H-
Phosphonates
90oC, the formed radical
7
interacts with hydroxyl radical that
is generated from Cu(I) with DTBP and H2O to form
intermediate . Finally, the intermediate
8
8
would undergo A mixture of alkenyls (0.5 mmol), H-phosphonates (2.0 mmol), CuCl
(0.05 mmol), FeCl3 (0.1 mmol), DTBP(1.0 mmol) and Et3N (0.5 mmol)
in DMSO (2.0 mL) under Ar was stirred at 110oC for 15 h. After the
completion of the reaction, the mixture was cooled to 25 oC and
then EtOAc and H2O were added to it. The organic layer was
separated and washed with brine, dried over Na2SO4. The volatiles
were removed under vacuum to afford the crude product, and
analyzed by GC. The crude product was purified by column
chromatography on silica gel and eluted with EtOAc/hexanes
(25/75) to afford the desired pure product.
oxidation to give the desired product 4.
Synthesis of β-Ketophosphonates from Alkenyls and H-
Phosphonates
A mixture of alkenyls (0.5 mmol), H-phosphonates (2.0 mmol), CuCl
(0.05 mmol), FeCl3 (0.1 mmol), DTBP(1.0 mmol) and Et3N (0.5 mmol)
in DMSO (2.0 mL) under Ar was stirred at 90oC for 15 h. After the
completion of the reaction, the mixture was cooled to 25 oC and
then EtOAc and H2O were added to it. The organic layer was
separated and washed with brine, dried over Na2SO4. The volatiles
were removed under vacuum to afford the crude product, and
analyzed by GC. The crude product was purified by column
chromatography on silica gel and eluted with EtOAc/hexanes
(25/75) to afford the desired pure product.
Scheme 2：Control Experiments.
Conclusions
In summary, we have developed a copper/iron-catalyzed
selective phosphorylation and oxyphosphorylation of alkenyls
with H-phosphonates protocol which provided a new and
powerful tool for the synthesis of alkenylphosphine oxides and
β-ketophosphonates. In addition, radical-trapping experiments
indicated that this transformation proceeded through a free-
radical process. The inexpensive catalysts (copper and iron
salts), good functional group tolerance, and the temperature-
controlled selectivity made this protocol more resourceful for
future applications.
Scheme 3：Proposed mechanism.
Experimental
General
Notes and references
* Chemical Engineering College, Nanjing University of Science &
Technology, Nanjing, Jiangsu 210094, P. R. China
E-mail: c.cai@mail.njust.edu.cn.
All chemical reagents are obtained from commercial suppliers and
used without further purification. All known compounds are
characterized by 1H NMR, 13C NMR, 31P NMR and compared with
previously reported data. Analytical thin-layer chromatography are
performed on glass plates precoated with silica gel impregnated
with a fluorescent indicator (254 nm), and the plates are visualized
Electronic Supplementary Information (ESI) available: [details of
any supplementary information available should be included
here]. See DOI: 10.1039/c000000x/
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 5 of 5
Organic & Biomolecular Chemistry
Please do not adjust margins
Journal Name
ARTICLE
1
(a) W. S. Wadsworth, W. D. Emmons, J. Am. Chem. Soc., 1961,
83, 1733; (b) J. Boutagy, R. Thomas, Chem. Rev., 1974, 74, 87;
(c) B. E. Maryanoff, A. B. Reitz, Chem. Rev., 1989, 89, 863; (d)
M. Kitamura, M. Tokunaga, R. Noyori, J. Am. Chem. Soc.,
1995, 117, 2931; (e) M. A. Chavez, S. Vargas, A. Suarez, E.
Alvarez, A. Pizzano, Adv. Synth. Catal., 2011, 353, 2775; (f) A.
Ryglowski, P. Kafarski, Tetrahedron, 1996, 52, 10685; (g) F.
Palacios, A. M. Ochoa de Retana, J. M. Alonso, J. Org. Chem.,
2006, 71, 6141; (h) M. Murai, M. Nakamura, K. Takai, Org.
Lett., 2014, 16, 5784; (i) Y. Zhou, S. Yin, Y. Gao, Y. Zhao, M.
Goto, L. Han, Angew. Chem., Int. Ed., 2010, 49, 6852; (j) W.
Debrouwer, T. S. A. Heugebaert, K. Van Hecke, C. V. Stevens,
J. Org. Chem., 2013, 78, 8232; (k) K. Radwan-Olszewska, F.
Palacios, P. Kafarski, J. Org. Chem., 2011, 76, 1170; (l) I.
Paterson, N. M. Gardner, K. G. Poullennec, A. E. Wright,
Bioorg. Med. Chem. Lett., 2007, 17, 2443; (m) O. Berger, J.
Montchamp, Chem. Eur. J. 2014, 20, 12385; (n) S. Ortial, H.
Fisher, J. Montchamp, J. Org. Chem. 2013, 78, 6599; (o) L. M.
Lentsch, D. F. Wiemer, Phosphorus, Sulfur and Silicon, 1999,
144, 573; (p) L. M. Lentsch, D. F. Wiemer, J. Org. Chem. 1999,
64, 5205.
8
9
(a)T. Otani, X. Jiang, K. Cho, R. Araki, N. Kutsumura, T. Saito,
Adv. Synth. Catal., 2015, 357
14D8O3I:;10(.1b0)3V9iSe/Cw. 7AOIrtnBicd0leu0O5,n0li5nPAe.
Subramanian, K. P. Kalappian, Eur. J. Org. Chem., 2014, 7193;
(c)P.-h. Chen, T. Xu, G. Dong, Angew. Chem., Int. Ed., 2014,
53, 1674; (d) J. Mahatthananchai, A. M. Dumas, J. W. Bode,
Angew. Chem., Int. Ed., 2012, 51, 10954.
(a) O. Tayama, A. Nakano, T. Iwahama, S. Sakaguchi, Y. Ishii, J.
Org. Chem. 2004, 69, 5494; (b) T. Kagayama, A. Nakano, S.
Sakaguchi, Y. Ishii, Org. Lett. 2006, 8, 407; (c) A. Maji, A.
,
Hazra, D. Maiti, Org. Lett., 2014, 16, 4524; (d) X. Chen, X. Li,
X.-L. Chen, L.-B. Qu, J.-Y. Chen, K. Sun, Z.-D. Liu, W.-Z. Bi, Y.-Y.
Xia, H.-T. Wu, Y.-F. Zhao, Chem.Commun. 2015, 51, 3846.
2
3
(a) S. K. Perumal, S. A. Adediran, R. F. Pratt, Bioorg. Med.
Chem., 2008, 16, 6987; (b) F. A. Cotton, R. A. Schunn, J. Am.
Chem. Soc., 1963, 85, 2394; (c) D. J. McCabe, E. N. Duesler, R.
T. Paine, Inorg. Chem., 1985, 24, 4626.
(a) K. M. Maloney, J. Y. L. Chung, J. Org. Chem., 2009, 74
,
7574; (b) X. Li, G. Hu, P. Luo, G. Tang, Y. Gao, P. Xu, Y. Zhao,
Adv. Synth. Catal., 2012, 354, 2427; (c) A. K. Bhattacharya, G.
Thyagarajan, Chem. Rev., 1981, 81, 415; (d) W. Wei, J.-X. Ji,
Angew. Chem., Int. Ed., 2011, 50, 9097; (e) N. Yi, R. Wang, H.
Zou, W. He, J. Org. Chem., 2015, 80, 5023; (f) M. Zhou, M.
Chen, Y. Zhou, K. Yang, J. Su, J. Du, Q. Song, Org. Lett., 2015,
17, 1786.
4
(a) T. Ogawa, N. Usuki, N. Ono, J. Chem. Soc., Perkin Trans.
1998, 17, 2953; (b) B. Bessieres, A. Schoenfelder, C. Verrat, A.
Mann, P. Ornstein, C. Pedregal, Tetrahedron Lett., 2002, 43
,
7659; (c) G. Evano, K. Tadiparthi, F. Couty, Chem. Commun.,
2011, 47, 179; (d) L. Liu, Y. Lv, Y.-L. Wu, X. Gao, Z.-P. Zeng, Y.-
X. Gao, G. Tang, Y.-F. Zhao, RSC Adv. 2014,
Kabalka, S. K. Guchhait, Org. Lett., 2003,
4
, 2322; (e) G. W.
5
, 729; (f) J. Hu, N.
Zhao, B. Yang, G. Wang, L.-N. Guo, Y.-M. Liang, S.-D. Yang,
Chem. – Eur. J., 2011, 17, 5516; (g) J.-F, Xue, S.-F, Zhou, O. T.
Asekun, Org. Biomol. Chem.,2015, 13,4896.
5
(a) L.-B. Han, M. Tanaka, J. Am. Chem. Soc., 1996, 118, 1571;
(b) L.-B. Han, N. Choi, M. Tanaka, J. Am. Chem. Soc., 1996,
118, 7000; (c) C.-Q. Zhao, L.-B. Han, M. Goto, M. Tanaka,
Angew. Chem., Int. Ed., 2001, 40, 1929; (d) C.-B. Lai, C.-J. Xi, C.
Chen, M.-M. Ma, X.-Y. Hong, Chem. Commun., 2003, 39
,
2736; (e) A. I. Kuramshin, A. A. Nikolaev, R. A. Cherkasov,
Mendeleev Commun., 2005, 155; (f) M. Niu, H. Fu, Y. Jiang, Y.
Zhao, Chem. Commun., 2007, 43, 272; (g) L.-B. Han, Y. Ono, S.
Shimada, J. Am. Chem. Soc., 2008, 130, 2752; (h) D. Lecercle,
M. Sawicki, F. Taran, Org. Lett., 2006,
8, 4283; (i) L. Liu, Y.-L.
Wu, Z.-S. Wang, J. Zhu, Y.-F. Zhao, J. Org. Chem., 2014, 79
,
6816; (j) I. G. Trostyanskaya, I. P. Beletskaya, Tetrahedron,
2014, 70, 2556; (k) L. L. Khemchyan, J. V. Ivanova, S. S.
Zalesskiy, V. P. Ananikov, I. P. Beletskaya, Z. A. Starikova, Adv.
Synth. Catal., 2014, 356, 771; (l) L.-B. Han, C. Zhang, H.
Yazawa, S. Shimada, J. Am. Chem. Soc., 2004, 126, 5080.
Q. Gui, L. Hu, X. Chen, J. Liu, Z. Tan, Chem. Commun., 2015,
51, 13922.
(a) J. D. Rivera-Ramirez, J. Escalante, A. Lopez-Munguia, A.
Martin, E. Castillo, J. Mol. Catal. B: Enzym., 2015, 112, 76; (b)
A. Uesugi, Z. Li, R. Yazaki, T. Ohshima, Angew. Chem., Int. Ed.,
2014, 53, 1611; (c) Z. Yang, S. Li, Z. Zhang, J. Xu, Org. Biomol.
Chem., 2014, 12, 9822; (d) S. R. Ban, H.-N. Wang, V. Toader,
D. S. Bohle, C.-J. Li, Org. Lett., 2014, 16, 6282; (e) H. Zeng, C.-
J. Li, Angew. Chem., Int. Ed., 2014, 53, 13862.
6
7
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins