Combined experimental/theoretical study of D-glucosamine promoted Ullmann-type C-N coupling catalyzed by copper(I): Does amino really count?

Article abstract of DOI:10.1039/c6ra03015g

Ullmann type C-N coupling reaction catalyzed by copper(I) with D-glucosamine derivatives as promoters was studied by means of combined experimental/theoretical investigation. The catalytic role of D-glucosamine was addressed. In contrast with previous speculations, the amino group may not count in the catalytic cycle in which the oxidative addition/reductive elimination mechanism works. Experimental results are in good agreement with theoretical findings. Extensive work indicates the wide applicability of the C-N coupling strategy exploited in this work.

Full text of DOI:10.1039/c6ra03015g

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PAPER
Combined experimental/theoretical study of
D-glucosamine promoted Ullmann-type C–N
coupling catalyzed by copper(I): does amino really
count?†
Cite this: RSC Adv., 2016, 6, 29638
b
b
c
Xin Ge,ab Xinzhi Chen, Chao Qian and Shaodong Zhou
*
*
Ullmann type C–N coupling reaction catalyzed by copper(I) with D-glucosamine derivatives as promoters
was studied by means of combined experimental/theoretical investigation. The catalytic role of
D-glucosamine was addressed. In contrast with previous speculations, the amino group may not count in
the catalytic cycle in which the oxidative addition/reductive elimination mechanism works. Experimental
results are in good agreement with theoretical findings. Extensive work indicates the wide applicability of
the C–N coupling strategy exploited in this work.
Received 1st February 2016
Accepted 14th March 2016
DOI: 10.1039/c6ra03015g
www.rsc.org/advances
Due to the high density of chiral information on the back-
bone and environmental benignity, carbohydrates have been
Introduction
widely used in organic synthesis, especially as efficient ligands.
Several reports has proved the effectiveness of carbohydrates in
promoting copper-catalyzed Ullmann coupling reaction. For
example, Cheng et al. found that D-glucosamine could efficiently
promote CuI catalyzed C–N coupling reaction;12a per-6-amino-b-
cyclodextrin was prepared as a supramolecular ligand for CuI
catalyzed N-arylation of imidazole with aryl bromide;12c Zhang
et al. also reported Ullmann type reaction by using D-glucos-
amine as ligand.12b In spite of the abundant ndings described
above, the associated catalytic mechanisms deduced at
a molecular level remain unclear. So far as reported, most
mechanistic investigations focused on the reactions catalyzed
by b-diketone-, 1,10-phenanthroline- and diamine-ligated
copper complexes.16 Compared with the single-electron-
transfer (SET) and atom-transfer mechanisms, the oxidative
addition/reductive elimination mechanism was more widely
accepted,16b,17 the corresponding intermediates are shown in
Scheme 1. As indicated by the oxidative addition/reductive
mechanism, the intermediate of CuIII was formed by the
The copper-catalyzed Ullmann coupling reaction is an impor-
tant strategy for C–N coupling, which plays a fundamental role
in pharmaceutical and agrochemical industry.1 Application of
the traditional copper-catalyzed Ullmann coupling reaction was
ꢀ
limited by the high temperature (about 200 C), stoichiometric
usage of catalyst and fastidiousness about the substrate. These
imperfections have inspired development of the prevalent
palladium-catalyzed cross-coupling reaction.2 In 2001, great
progress reported by Buchwald indicated that ligand diamines
could efficiently improve the copper-catalyzed cross-coupling of
N–H heterocycles with aryl halides;3 the aerward work done by
Cristau and Taillefer also provided such C–N coupling strategies
with high efficiencies alternatively by using Schiff bases and
oximes as ligand.4 The prospect of Ullmann coupling reaction
catalyzed by copper catalysts is to perform such processes in
more economic way. Up till now, while various ligands such as
diamines,3,5 glycol,6 Schiff base,4,7 amino acids,8 diketones,9
phenanthroline,10 2,20-bipyridine,11 carbohydrates,12 oxalamic
acid,13 diamide,14 have already been proved efficient for
promoting the targeted coupling reactions, it is always chal-
lenging and interesting to develop eco-friendly and more effi-
cient ligand,15 as well as to unravel the associated mechanistic
aspects.
aSchool of Chemical and Material Engineering, Jiangnan University, Wuxi, P. R. China
bKey Laboratory of Biomass Chemical Engineering of Ministry of Education, College of
Chemical and Biological Engineering, Zhejiang University, Hangzhou, P. R. China.
E-mail: qianchao@zju.edu.cn
c
¨
¨
Institut fur Chemie, Technische Universitat Berlin, Straße des 17. Juni 135, 10623
Berlin, Germany. E-mail: shaodong.zhou@campus.tu-berlin.de
† Electronic supplementary information (ESI) available. See DOI:
10.1039/c6ra03015g
Scheme 1 The intermediates reported in previous studies.
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Table 1 Ligand effect on CuI-catalyzed coupling of 4-iodoanisole and
viewpoint in D-glucosamine/CuI catalyzed the Ullmann type C–S
coupling reaction.21 However, considering the very activity of L1,
possibly, rather than the amino it is the hydroxyls that work in
the present C–N coupling processes. To verify this speculation,
we protected the hydroxyl and exposed the amino groups of L2,
respectively. Thus, L6, L7, L8 and L9 were obtained by protect-
ing the hydroxyl groups in the position C-4 and C-6. However,
copper complexes prepared with these ligands are completely
inactive in promoting the coupling reaction, no matter if the
amino group is acylated (L6, L7) or not (L8, L9). Alternatively, by
just protecting the amino group and exposing some hydroxyl
groups, L3, L4, and L5 were obtained, which turned out to be
very active for the model coupling reaction. Moreover, only
protecting the hydroxyl group in the position C-1 of L3 (i.e. L4
and L5) does not affect the activities of ligands obviously.
Compared with L1–L5, while L6–L9 are much more conforma-
tionally rigid, and sterically hindered, the sharp contrast in
Table 1 clearly indicates that the amino or imino group maybe
not count in the catalytic process. Thus, as the most effective
promoter, the prototype of L2 and L3, i.e. D-glucosamine, was
selected for theoretical investigation presented later.
imidazolea
Ligand
L1
73
L2
85
L3
84
L4
76
L5
73
L6
0
L7
0
L8
0
L9
0
Yieldb/%
a
Reaction conditions: 4-iodoanisole 1a (1.0 mmol), imidazole 2a (1.2
mmol), K2CO3 (2.0 mmol), CuI (0.1 mmol) and ligand (0.1 mmol) in
b
the DMSO–water (5 mL, 1 : 1/v/v) at 110 ꢀC for 24 h. Isolated yield.
oxidative addition of
a
ligand (Ln)–CuI–nucleophile (Nu)
complex with the aryl halide.16e,18 Moreover, it was also
concluded that the rate-limiting step was oxidative addition of
ligand (Ln)–CuI–nucleophile (Nu) complex with the aryl
halide.16b,17,19
Our recently interest focuses on the ligand- and catalytic
effect of carbohydrates,20 we herein present mechanistic study
on D-glucosamine promoted C–N coupling reactions catalyzed
by copper catalyst. The experimental study on ne-tuning and
design of D-glucosamine-derived ligand was complemented by
theoretical investigation using DFT calculation.
Scheme 2 Possible active complexes that are directly involved in the
C–N coupling processes.
Result and discussion
To rationally obtain some mechanistic information experi-
mentally, the D-glucosamine-derived ligand were nely tuned
and designed. The coupling of 4-iodoanisole (1.0 equiv.) and
imidazole (1.2 equiv.) was adopted as the model reaction, and
detailed results are shown in Table 1. First, when D-glucose (L1)
and D-glucosaminium chloride (L2) were used as ligands, the
coupling product 3a was obtained with yields of 73% and 85%,
respectively, which is consistent with previous reports.12a,b
Pitchumani speculated the catalytic mechanism of CuI/per-6-
amino-b-cyclodextrin that the ligand–CuI complex was obtained
by interaction between the amino groups of per-6-amino-b-
Fig. 1 PES and relevant structural sketches of the most favorable
reaction pathways for D-glucosamine promoted C–N(1) coupling
cyclodextrin and CuI.12c Zhang et al. elaborated the similar reaction; charges are omitted for the sake of clarity.
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and Cu–N bonds, generating IM3c. Finally, dissociation of IM3c
liberates the coupling product 1-phenyl-1H-imidazole and
regenerates Cat. A or B. For this stepwise C–N coupling process,
insertion of the Cu atom into the C–I bond serves as the rate
limiting step. In addition, both Cat. A and B are capable of
bringing about a coupling process proceeding via pathway c.
For C–N(3) coupling, once again, the same mechanisms for
reactions promoted by Cat. A and B were addressed, and two
energetically most favorable pathways were found. Likewise,
elucidation of only the more preferable pathway, e is to be
presented. As shown in Fig. 2, the transformations starts from
an encounter complex IM1e in which the N(3) atom coordinates
with the metal center, and the initial step involves insertion of
the Cu atom into the C–I bond of iodobenzene via TS1e/2e. Next,
the C–N(3) coupling is achieved via TS2e/3e, forming the
Fig. 2 PES and relevant structural sketches of the most favorable
reaction pathways for D-glucosamine promoted C–N(3) coupling
reaction; charges are omitted for the sake of clarity.
Table 2 The coupling reaction of 4-iodoanisole and imidazole cata-
lyzed by copper/L3a
The reaction mechanisms were interrogated with DFT
calculations. As found in the experiments, the amino maybe not
count in the catalytic process. We attempted to clarify the active
ligand–CuI complex structure by DFT rst. As concluded above,
other than the amine, hydroxyls on the C3, C4 and C6 positions
are crucial for the CuI catalyzed Ullmann reaction promoted by
glucosamine derivatives. Thus, two oxo-ligated Cu complexes,
i.e. Cat. A and B and two N–O ligated Cu complexes, i.e. Cat. C
and D (as shown in Scheme 2), are considered as the possible
active species that directly catalyze the reaction. However, the
structure of Cat. C and D can't converge by DFT. It tallies with
the experiment results. In addition, C–N couplings involving
either N atom of 1H-imidazole are taken account. The potential
energy surfaces (PES) and relevant structural sketches of the
most favorable reaction pathways are shown in Fig. 1–3; more
detailed structural information is given in the ESI.†
Entry Copper salt Base
Solvent
Temp/ꢀC Yieldb/%
1
2
3
4
5
6
7
8
CuI
K2CO3 DMSO–water (1 : 1) 110
K2CO3 DMSO–water (1 : 1) 110
K2CO3 DMSO–water (1 : 1) 110
K2CO3 DMSO–water (1 : 1) 110
K2CO3 DMSO–water (1 : 1) 110
84
37
24
71
76
32
61
21
Trace
69
91
57
65
60
40
68
75
CuCl
CuCl2
CuSO4
Cu(OAc)2
CuI
CuI
CuI
CuI
CuI
CuI
CuI
CuI
CuI
CuI
CuI
CuI
K2CO3 DMF
K2CO3 DMSO
K2CO3 Methanol
K2CO3 Water
K2CO3 DMF–water (1 : 1)
110
110
110
110
110
For C–N(1) coupling, as shown in Fig. 1, the reactions
promoted by Cat. A and B proceed via the same mechanisms,
and three most probable pathways were located. Being found as
the thermodynamically most favorable one, pathway c is
selected for more detailed elucidation. From an encounter
9
10
11
12
13
Cs2CO3 DMSO–water (1 : 1) 110
KOH
NaOH
DMSO–water (1 : 1) 110
DMSO–water (1 : 1) 110
complex IM1c, in which the N–H bond has already been acti- 14
Na2CO3 DMSO–water (1 : 1) 110
Cs2CO3 DMSO–water (1 : 1) 80
Cs2CO3 DMSO–water (1 : 1) 100
Cs2CO3 DMSO–water (1 : 1) 120
15
16
17
vated barrierlessly and the N(1) atom coordinates with the metal
center, an initial insertion of the Cu atom into the C–I bond of
iodobenzene takes place via TS1c/2c, forming the Cu–C and Cu–
I bonds, respectively. Subsequent step corresponds to forma-
a
Reaction conditions: 4-iodoanisole 1a (1.0 mmol), imidazole 2a (1.2
mmol), base (2.0 mmol), copper salt (0.1 mmol) and L3 (0.1 mmol) in
tion of the C–N bond with concomitant cleavage of the Cu–C
b
the solvent (5 mL) for 24 h. Isolated yield.
Fig. 3 PES and relevant structural sketches of the most favorable reaction pathways for bare CuI catalyzed reaction; charges are omitted for the
sake of clarity.
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Table 3 CuI/L3 catalyzed C–N coupling reactiona
Entry
1
Aryl halides 1
Nitrogen compound
Product
Yieldb/%
91 (3a)
2
3
4
5
6
7
8
94 (3b)
95 (3c)
87 (3d)
89 (3e)
86 (3f)
81 (3f)
Trace
9
76 (3g)
69 (3h)
10
11
12
57 (3i)
99 (3j)
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Table 3 (Contd.)
Entry
Aryl halides 1
Nitrogen compound
Product
Yieldb/%
13
71 (3k)
a
Reaction conditions: aryl halides 1 (1.0 mmol), nitrogen nucleophiles 2 (1.2 mmol), Cs2CO3 (2.0 mmol) and CuI (0.1 mmol) in the DMSO–water (5
b
mL, 1 : 1/v/v) at 110 ꢀC for 24 h. Isolated yield.
product complex IM3e. Finally, release of 1-phenyl-1H-imidazol- and it was found that polar aprotic solvent favors this coupling
3-ium iodide regenerates Cat. A. Although energy barrier of the reaction (Table 1, Entry 6–9). While water is not an ideal solvent,
rate limiting step of pathway e, i.e. IM1e / IM2e, is comparable it serves to increase the solubility of ligand in the mixed solvents,
with that of pathway c, the much lower stability of encounter DMSO–water (1 : 1) and DMF–water (1 : 1), so as to increase the
complex IM1e as compared to IM1c makes formation of the reaction efficiencies (Table 2, Entry 1 and 10). Further, Cs2CO3
former much less efficient, so that pathway e is bypassed. Thus, outperforms all the other bases employed (Table 1, Entry 11–14).
only C–N(1) coupling is available according to our calculation. With regard to the reaction temperature, the reactions at 110 ꢀC
To make it clear if the effect of ligands is just to increase the proceeds most efficiently (Table 1, Entry 15–17). Thus, the
solubility of Cu or more than that, the reaction of bare CuI optimum conditions are obtained: Cs2CO3 as the acid-binding
catalyzed C–N coupling process was also calculated; PES and reagent, DMSO–water (1 : 1) as solvent, 110 ꢀC. In addition,
relevant structural sketches of the most favorable pathway (f) are CuI and DMSO were selected as catalyst precursor and solvent,
shown in Fig. 3, and more detailed structural information is respectively for subsequent theoretical investigation.
given in the ESI.† Alternative mechanisms were addressed for
Further extensive study focused on expanding the substrate
bare CuI catalyzed reaction. Initially, a s-bond metathesis scope for CuI/L3 catalyzed Ullmann coupling reaction; more
process takes place via cleavage of the Cu–I and N–H bonds to details are shown in Table 3. To our delight, both electron-
form IM5, with concomitant formation of the Cu–N and I–H withdrawing and electron-donating aryl iodides react efficiently
bonds. Next, another s-bond metathesis process is involved in with imidazole and the targeted products were obtained with
subsequent reaction of intermediate IM6 with iodobenzene to good to excellent yields (Table 3, Entry 1–6). In addition, neither
generate IM8, that is, formation of C–N and the new Cu–I bonds electron withdrawing nor donating groups substituted on the
is accomplished under cleavage of the Cu–N and C–I bonds. phenyl ring has obvious inuence on the yields. Next, we
Finally, liberation of 1-phenyl-1H-imidazole regenerates the bare examined the inuences of different halides(Table 3, Entry 6–8),
CuI. The initial activation of the Cu–I and N–H bonds corre- and the corresponding reactivities with imidazole decrease in
sponds to the rate limiting step; here, the energy barrier (212 kJ the order PhI > PhBr > PhCl. Consideriꢁn1g the increasing
molꢁ1) is much higher as compared to pathway c (85 kJ molꢁ1). BDE(C6H5–X):22 BDE(C6H5–I) ¼ 272.0 kJ mol < BDE(C6H5–Br)
To be concluded from the computational results, D-glucos- ¼ 336.4 kJ molꢁ1 < BDE(C6H5–Cl) ¼ 397.9 kJ molꢁ1, the experi-
amine has considerably promotive effect on the C–N coupling mental result is in line with our theoretical conclusion that
reaction in that, alternative pathways are available such that insertion of the C–X bond serves as the rate limiting step.
much lower activation energy is needed; the oxidative addition/ Further, experiments with the different nitrogen nucleophiles
reductive elimination mechanisms are addressed; only C–N(1) were performed, and several N–H heterocycles including 1H-
coupling is available; both Cat. A and B can serve as the active benzimidazole, morpholine, pyrrolidine give the corresponding
complex that directly promotes a catalytic cycle.
products in moderate to excellent yields.
For C–N coupling reaction, L1 and L2 have been reported, but
As the nal part of this work, we present a tricky application
L3 was not involved in this reaction. Thus, L3 selected for further of the C–N coupling strategy in the synthesis of 1-(4-methoxy-
examination, and detailed results can be found in Table 2. phenyl)indoline, which is abundant in nature and widely
Comparison of different copper sources, i.e. CuI, CuCl, CuCl2, employed in biological and pharmaceutical chemistry.23 As
CuSO4 and Cu(OAc)2, showed that CuI was the best copper shown in Scheme 3, 1-(4-methoxyphenyl)indoline was obtained
source (Table 2, Entry 1–5). Next, a series of solvents were tested from 2-bromo-phenethylamine stepwisely via intramolecular
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Scheme 3 Application of the Cu/L3-catalyzed C–N coupling reaction in the one-pot synthesis of 1-(4-methoxyphenyl)indoline.
cyclization and subsequent coupling with 4-iodoanisole in one mmol, 19 mg), ligand (0.1 mmol) and Cs2CO3 (2 mmol) at room
ꢀ
pot; the yield amounts to 69%. All the above extensive reactions temperature. Then the reaction mixture was heated to 110 C
indicate the wide applicability of the C–N coupling strategy under air and stirred for 24 h. Aer cooling to room tempera-
exploited in this work.
ture, the reaction mixture was partitioned by adding the ethyl
acetate (20 mL) and water (20 mL). Subsequently, the organic
phase was separated and the aqueous phase was extracted with
ethyl acetate (20 mL) twice. The combined organic phases were
washed with saturated brine, dried over MgSO4, and concen-
trated in vacuo. Then the crude product was puried by column
chromatography through silica gel, eluting with ethyl acetate/
petroleum ether solvent mixture, to give the pure 3.
Conclusions
In summary, we have presented the combined experimental/
theoretical investigation on the D-glucosamine derivatives
promoted Ullmann type C–N coupling reactions catalyzed by
copper. In the rst part, by nely tuning and designing the
ligands, it was found that the hydroxyls on the C-3, C-4 and C-6
position may have signicant inuence on the catalysis process,
while the hydroxyl on C-1 and the amino do not count. Subse-
quently, by using DFT calculation, not only the catalytic role of
D-glucosamine was addressed, but also the inactiveness of bare
CuI was explained. Here, the oxidative addition/reductive
elimination mechanism works, and experimental results are
in good agreement with theoretical ndings. Next, extensive
work was performed by employing various phenyl halide and
amines as substrates, and moderate to excellent yields of cor-
responding coupling products were obtained. Finally, the wide
applicability of the coupling strategy was further proved by
a tricky application in the efficient preparation of 1-(4-methox-
yphenyl)indoline starting from 2-bromo-phenethylamine.
General procedure for one-pot synthesize of
1-(4-methoxyphenyl)indoline
To a stirred solution of DMSO–water (1 : 1, 5 mL) were added 2-
bromo-phenethylamine (1.0 mmol), CuI (0.1 mmol, 19 mg), L3
(0.1 mmol) and Cs2CO3 (4 mmol) at room temperature. Then
the reaction mixture was heated to 110 ꢀC under air and stirred
for 24 h. Subsequently, 4-iodoanisole (1.0 mmol) was added to
this solution and continued to stir for 24 h. Aer cooling to
room temperature, the reaction mixture was partitioned by
adding the ethyl acetate (20 mL) and water (20 mL). Subse-
quently, the organic phase was separated and the aqueous
phase was extracted with ethyl acetate (20 mL) twice. The
combined organic phases were washed with saturated brine,
dried over MgSO4, and concentrated in vacuo. Then the crude
product was puried by column chromatography through silica
gel, eluting with ethyl acetate/petroleum ether solvent mixture,
to give the pure product.
General methods
Melting points were determined on an X4-Data microscopic
melting point apparatus and were uncorrected. Nuclear
magnetic resonance (NMR) spectra were measured at 400 MHz
(1H) or at 100 MHz (13C) on a Bruker Avance DRX-400 spec-
trometer. All reactions were monitored by analytical thin-layer
chromatography (TLC) from Merck with detection by spraying
with 5% (w/v) phosphomolybdic acid in ethanol and subse-
quent heating or UV. The products were puried by column
chromatography through silica gel (300–400 mesh). D-Glucose,
D-glucosamine and N-acetyl-D-glucosamine were purchased in
Aladdin Industrial Corporation. All reagents and solvents were
general reagent grade unless otherwise stated.
Computational details
The theoretical work was performed using the Gaussian 09
program.24 The def2-TZVP basis set25 with the ECP-28 pseudo-
potential26 were used for the I atom, and the def2-TZVP all-
electron basis set25 was chosen for the Cu atoms; for all the
other atoms, the def2-SVP all-electron basis set25 was used for
optimization and frequency analysis (BSI), and the def2-TZVP
all-electron basis set25 (BSII) for calculating the single-point
energies. The Polarizable Continuum Model using the integral
equation formalism variant (IEFPCM)27 was employed to eval-
uate the solvation energies. The B97-1 functional28 was
employed for geometry optimizations and frequency analysis,
General procedure of CuI@ligand catalyzed coupling reaction
of N–H heterocycles and aryl halides
To a stirred solution of DMSO–water (1 : 1, 5 mL) were added which has previously been proven to be reliable for calculating
aryl halide (1.0 mmol), N–H heterocycle (1.2 mmol), CuI (0.1 Cu complexes.29 Stationary points were optimized without
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symmetry constraint, and their nature conrmed by vibrational 10 R. A. Altman and S. L. Buchwald, Org. Lett., 2006, 8, 2779.
frequency analysis. Intrinsic reaction coordinate30 calculations 11 C. Zhang, B. Huang, A. Q. Bao, X. Li, S. Guo, J. Q. Zhang,
were performed to link transition structures with the respective
intermediates. Unscaled vibrational frequencies were used to
J. Z. Xu, R. Zhang and D. M. Cui, Org. Biomol. Chem., 2015,
13, 11432.
correct the relative energies for zero-point energy (ZPE) 12 (a) D. P. Cheng, F. F. Gan, W. X. Qian and W. L. Bao, Green
contributions.
Chem., 2008, 10, 171; (b) M. Wen, C. Shen, L. F. Wang,
P. F. Zhang and J. Z. Jin, RSC Adv., 2015, 5, 1522; (c)
P. Suresh and K. Pitchumani, J. Org. Chem., 2008, 73, 9121.
13 (a) Y. Zhang, X. Y. Yang, Q. Z. Yao and D. W. Ma, Org. Lett.,
2012, 14, 3056; (b) Y. B. Wang, Y. Zhang, B. B. Yang, A. Zhang
and Q. Z. Yao, Org. Biomol. Chem., 2015, 13, 4101.
Acknowledgements
The authors are grateful for the nancial support from the
Natural Science Foundation of China (21376213, 21476194),
Zhejiang Provincial Public Technology Research of China 14 W. Zhou, M. G. Fan, J. L. Yin, Y. W. Jiang and D. W. Ma, J. Am.
(2014C31123, 2015C31038) and the Fundamental Research
Funds for the Central Universities (JUSRP115A05).
Chem. Soc., 2015, 137, 11942.
15 (a) L. Liang, Z. K. Li and X. G. Zhou, Org. Lett., 2009, 11, 3294;
(b) F. T. Wu, N. N. Yan, P. Liu, J. W. Xie, Y. Liu and B. Dai,
Tetrahedron Lett., 2014, 55, 3249; (c) J. W. Xie, X. H. Zhu,
M. N. Huang, F. Meng, W. W. Chen and Y. Q. Wan, Eur. J.
Org. Chem., 2010, 3219; (d) X. F. Li, D. S. Yang, Y. Y. Jiang
and H. Fu, Green Chem., 2010, 12, 1097; (e) D. P. Wang,
F. X. Zhang, D. Z. Kuang, J. X. Yu and J. H. Li, Green
Chem., 2012, 14, 1268.
Notes and references
1 (a) F. Monnier and M. Taillefer, Angew. Chem., Int. Ed., 2009,
48, 6954; (b) D. A. Horton, G. T. Bourne and M. L. Smythe,
Chem. Rev., 2003, 103, 893; (c) R. B. Bambal and
R. P. Hanzlik, Chem. Res. Toxicol., 1995, 8, 729; (d) V. Nair,
S. Bindu and V. Sreekumar, Angew. Chem., Int. Ed., 2005, 16 (a) G. O. Jones, P. Liu, K. N. Houk and S. L. Buchwald, J. Am.
44, 1907; (e) T. Wiglenda, I. Ott, B. Kircher, P. Schumacher,
D. Schuster, T. Langer and R. Gust, J. Med. Chem., 2005,
48, 6516; (f) M. Voets, I. Antes, C. Scherer, U. Muller-Vieira,
K. Biemel, S. Marchais-Oberwinkler and R. W. Hartmann,
J. Med. Chem., 2006, 49, 2222; (g) I. P. Beletskaya and
V. P. Ananikov, Chem. Rev., 2011, 111, 1596; (h) J. Bariwal
and E. Van der Eycken, Chem. Soc. Rev., 2013, 42, 9283; (i)
I. P. Beletskaya and A. V. Cheprakov, Coord. Chem. Rev.,
2004, 248, 2337.
Chem. Soc., 2010, 132, 6205; (b) P. F. Larsson, C. J. Wallentin
and P. O. Norrby, ChemCatChem, 2014, 6, 1277; (c)
E. R. Strieter, D. G. Blackmond and S. L. Buchwald, J. Am.
Chem. Soc., 2005, 127, 4120; (d) J. W. Tye, Z. Weng,
A. M. Johns, C. D. Incarvito and J. F. Hartwig, J. Am. Chem.
Soc., 2008, 130, 9971; (e) E. R. Strieter, B. Bhayana and
S. L. Buchwald, J. Am. Chem. Soc., 2009, 131, 78; (f) R. Giri
and J. F. Hartwig, J. Am. Chem. Soc., 2010, 132, 15860.
17 S. L. Zhang and Y. Q. Ding, Organometallics, 2011, 30, 633.
2 (a) A. S. Guram, R. A. Rennels and S. L. Buchwald, Angew. 18 (a) S. L. Zhang, L. Liu, Y. Fu and Q. X. Guo, Organometallics,
Chem., Int. Ed. Engl., 1995, 34, 1348; (b) J. Louie and
J. F. Hartwig, Tetrahedron Lett., 1995, 36, 3609; (c)
2007, 26, 4546; (b) H. Z. Yu, Y. Y. Jiang, Y. Fu and L. Liu, J.
Am. Chem. Soc., 2010, 132, 18078.
J. F. Hartwig, Angew. Chem., Int. Ed., 1998, 37, 2046; (d) 19 G. Lefevre, G. Franc, C. Adamo, A. Jutand and I. Cioni,
E. A. B. Kantchev, C. J. O'Brien and M. G. Organ, Angew.
Chem., Int. Ed., 2007, 46, 2768.
Organometallics, 2012, 31, 914.
20 (a) C. Shen, P. F. Zhang and X. Z. Chen, Helv. Chim. Acta,
2010, 93, 2433; (b) C. Shen, H. J. Xia, H. Zheng, P. F. Zhang
and X. Z. Chen, Tetrahedron: Asymmetry, 2010, 21, 1936; (c)
C. Shen, F. Y. Shen, H. J. Xia, P. F. Zhang and X. Z. Chen,
Tetrahedron: Asymmetry, 2011, 22, 708; (d) C. Shen, F. Shen,
G. Zhou, H. Xia, X. Chen, X. Liu and P. Zhang, Catal.
Commun., 2012, 26, 6; (e) C. Shen, H. J. Xia, H. Yan,
X. Z. Chen, S. Ranjit, X. J. Xie, D. Tan, R. Lee, Y. M. Yang,
B. G. Xing, K. W. Huang, P. F. Zhang and X. G. Liu, Chem.
Sci., 2012, 3, 2388; (f) X. Ge, C. Qian and X. Z. Chen,
Tetrahedron: Asymmetry, 2014, 25, 1450; (g) X. Ge, C. Qian,
Y. B. Chen and X. Z. Chen, Tetrahedron: Asymmetry, 2014,
25, 596.
3 (a) A. Klapars, J. C. Antilla, X. H. Huang and S. L. Buchwald, J.
Am. Chem. Soc., 2001, 123, 7727; (b) A. Klapars, X. H. Huang
and S. L. Buchwald, J. Am. Chem. Soc., 2002, 124, 7421; (c)
J. C. Antilla, J. M. Baskin, T. E. Barder and S. L. Buchwald,
J. Org. Chem., 2004, 69, 5578.
4 H. J. Cristau, P. P. Cellier, J. F. Spindler and M. Taillefer,
Chem.–Eur. J., 2004, 10, 5607.
5 D. S. Surry and S. L. Buchwald, Chem. Sci., 2010, 1, 13.
6 (a) F. Y. Kwong, A. Klapars and S. L. Buchwald, Org. Lett.,
2002, 4, 581; (b) B. Yang, Z. X. Mao, X. H. Zhu and
Y. Q. Wan, Catal. Commun., 2015, 60, 92.
7 Y. Wang, J. Y. Gao, M. D. Zhao and J. M. Li, Chem. Res. Chin.
Univ., 2015, 31, 549.
8 (a) D. W. Ma and Q. Cai, Synlett, 2004, 128; (b) J. M. Tang,
21 M. Yang, H. Y. Shen, Y. Y. Li, C. Shen and P. F. Zhang, RSC
Adv., 2014, 4, 26295.
B. Q. Xu, X. Mao, H. Y. Yang, X. X. Wang and X. Lv, J. Org. 22 Y. R. Luo, Handbook of Bond Dissociation Energies in Organic
Chem., 2015, 80, 11108.
Compounds, CRC Press, Boca Raton, London, New York,
9 (a) A. Shar and S. L. Buchwald, J. Am. Chem. Soc., 2006, 128,
Washington, D.C., 2002.
8742; (b) B. de Lange, M. H. Lambers-Verstappen, L. S. van de 23 (a) L. Basolo, A. Bernasconi, E. Borsini, G. Broggini and
Vondervoort, N. Sereinig, R. de Rijk, A. H. M. de Vries and
J. G. de Vries, Synlett, 2006, 3105.
E. M. Beccalli, ChemSusChem, 2011, 4, 1637; (b) J. Q. Liu,
C. Qian and X. Z. Chen, Synthesis, 2010, 403.
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24 M. J. Frisch; G. W. Trucks; H. B. Schlegel; G. E. Scuseria; 25 F. Weigend and R. Ahlrichs, Phys. Chem. Chem. Phys., 2005,
M. A. Robb; J. R. Cheeseman; G. Scalmani; V. Barone; 7, 3297.
B. Mennucci; G. A. Petersson; H. Nakatsuji; M. Caricato; 26 B. Metz, H. Stoll and M. Dolg, J. Chem. Phys., 2000, 113, 2563.
X. Li; H. P. Hratchian; A. F. Izmaylov; J. Bloino; G. Zheng; 27 G. Scalmani and M. J. Frisch, J. Chem. Phys., 2010, 132,
J. L. Sonnenberg; M. Hada; M. Ehara; K. Toyota;
R. Fukuda; J. Hasegawa; M. Ishida; T. Nakajima; Y. Honda; 28 F. A. Hamprecht, A. J. Cohen, D. J. Tozer and N. C. Handy, J.
O. Kitao; H. Nakai; T. Vreven; J. A. Montgomery Jr; Chem. Phys., 1998, 109, 6264.
J. E. Peralta; F. Ogliaro; M. Bearpark; J. J. Heyd; 29 (a) S. M. Tekarli, M. L. Drummond, T. G. Williams,
114110.
E. Brothers; K. N. Kudin; V. N. Staroverov; R. Kobayashi;
J. Normand; K. Raghavachari; A. Rendell; J. C. Burant;
S. S. Iyengar; J. Tomasi; M. Cossi; N. Rega; J. M. Millam;
M. Klene; J. E. Knox; J. B. Cross; V. Bakken; C. Adamo;
J. Jaramillo; R. Gomperts; R. E. Stratmann; O. Yazyev;
A. J. Austin; R. Cammi; C. Pomelli; J. W. Ochterski;
R. L. Martin; K. Morokuma; V. G. Zakrzewski; G. A. Voth;
T. R. Cundari and A. K. Wilson, J. Phys. Chem. A, 2009, 113,
8607; (b) W. Y. Jiang, M. L. Laury, M. Powell and
A. K. Wilson, J. Chem. Theory Comput., 2012, 8, 4102; (c)
W. J. Zhang, D. G. Truhlar and M. S. Tang, J. Chem. Theory
Comput., 2013, 9, 3965; (d) S. J. Luo, B. Averkiev,
K. R. Yang, X. F. Xu and D. G. Truhlar, J. Chem. Theory
Comput., 2014, 10, 102.
P. Salvador; J. J. Dannenberg; S. Dapprich; A. D. Daniels; 30 (a) H. P. Hratchian and H. B. Schlegel, J. Chem. Theory
O. Farkas; J. B. Foresman; J. V. Ortiz; J. Cioslowski and
D. J. Fox, Gaussian 09.
Comput., 2005, 1, 61; (b) D. G. Truhlar, N. J. Kilpatrick and
B. C. Garrett, J. Chem. Phys., 1983, 78, 2438; (c) K. Fukui,
Acc. Chem. Res., 1981, 14, 363.
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