Palladacycles derived from arylphosphinamides for mild Suzuki-Miyaura cross-couplings

Article abstract of DOI:10.1039/c5ra12742d

We present a type of palladacyclic complexes derived from arylphosphinamides which can be used as efficient and versatile precatalysts for mild Suzuki-Miyaura cross-coupling. With the presence of 1.0 mol% of palladacycles, a wide variety of aryl bromides and boronic acids could be coupled very efficiently at ambient temperature and under air atmosphere without the need of external supporting ligands. Moreover, the mild conditions also allow for smooth coupling of electron-deficient, i.e., the less stable aryl triflates. In addition to the highly catalytic activity, the palladacyclic complexes can be very easily prepared through a two-step procedure from the readily affordable diphenyl-phosphinic chloride and exhibit excellent stability toward air and moisture. Due to these prominent properties, the new palladacycles would find practical use in Suzuki-Miyaura couplings.

Full text of DOI:10.1039/c5ra12742d

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DOI: 10.1039/C5RA12742D
Journal Name
COMMUNICATION
Palladacycles Derived from Arylphosphinamides for Mild Suzuki-
Miyaura Cross-Couplings
Guo-Jie Wu,a,b Fu-She Han,a,c* and Yu-Long Zhaob*
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
www.rsc.org/
We present a type of palladacyclic complexes derived from couplings are usually performed atelevated temperature. Mild
arylphosphinamides which can be used as efficient and versatile couplings often require the support of expensive ligands such
precatalysts for mild Suzuki-Miyaura cross-coupling. With the as electron-rich phosphines and N-heterocarbenes (NHC).5,6
presence of 1.0 mol% of palladacycles, a wide variety of aryl The ligand-free couplings under mild conditions are relatively
bromides and boronic acids could be coupled very efficiently at rare.7 Second, the couplings of thermally instable boronic acids
ambient temperature and under air atmosphere without the need such as polyfluorophenyl8 and five-membered 2-hetero-
of external supporting ligands. Moreover, the mild conditions also aromatic9 are still problematic although a powerful catalyst
allow for smooth coupling of electron-deficient, i.e., the less system has been reported recently by Buchwald.10 Third, aryl
stable aryl triflates. In addition to the highly catalytic activity, the triflates are attractive electrophiles due to their high reactivity;
palladacyclic complexes can be very easily prepared through a however, the couplings of such substrates, particularly the
two-step procedure from the readily affordable diphenyl- electron-deficient derivatives are sometimes troublesome due
phosphinic chloride and exhibit excellent stability toward air and to the ease of decomposition of substrates.11 Finally, many
moisture. Due to these prominent properties, the new catalysts with high catalytic activity are often less stable
palladacycles would find practical use in Suzuki-Miyaura couplings. toward air and moisture, which restricts their practical
applications. As such, the development of new catalyst
systems aimed at solving these issues is still highly desired in
Suzuki-Miyaura coupling.
Introduction
Among the transition-metal-catalyzed cross-coupling reaction, the
Suzuki-Miyaura cross-coupling has been accepted as the first choice
Results and discussion
for the creation of C(sp2)–C(sp2) bonds.1 This is attributed to
numerous advantages offered by this protocol including the broad In our efforts devoted to the development of new catalyst
functional group tolerance, the abundance of aryl/alkenyl- systems for efficient Suzuki-Miyaura coupling3e,12 and direct C–
(pseudo)halides, and the highly stable and low toxic nature of boron
H
functionalization for the synthesis of phosphorus
reagents. In addition, the boron by-products could also be easily compounds,13 we have synthesized a novel palladacyclic
separated from the reaction mixtures. Great academic achieve-
ments have been made both with palladium2 and nickel-catalysts.3
Moreover, the practicality of a number of catalyst systems in
pharmaceutical, agrochemical, and fine chemical industries have
also been successfully demonstrated.4
Despite these remarkable advances, several challenging
issues remain to be overcome. First, the Suzuki-Miyaura
O
A)
Ph
O
ArFNH2
base
Ph
O
P
R
Ph
Pd(II)
N
P
R
P
N
Cl
H
Pd
DMF
3a
R = C6F5
3b R = p-CF3C6F4
1a
2a R = C6F5
2b
R = p-CF3C6F4
O
a.Key Lab of Synthetic Rubber,Changchun Institute of Applied Chemistry, Chinese
Academy of Sciences, 5625 Renmin Street, Changchun, Jilin, 130022,China; Fax:
(+86)-431-85262926; phone: (+86)-431-85262936; email: fshan@ciac.ac.cn
b.Department of Chemistry, Northeast Normal University, Changchun, Jilin
130024,China; email: zhaoyl351@nenu.edu.cn
BQ (10 mol%)
CsF (1.0 equiv)
DMF, 40 oC
Ph
P
C6F5
B)
3a (HO)2B
N
H
Me
+
Me
4a
c.State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian
116024, China
5a, 93%
Scheme 1 Preparation of palladium complex 3 and the reaction
†Electronic Supplementary Information (ESI) available: Experimental, spectral data and
copies of spectra. See DOI: 10.1039/x0xx00000x
property.13a
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Journal Name
complex
3
from the readily available diphenylphosphinic we evaluated the catalytic efficiency of 3a using 4-bromotoluene 6a
View Article Online
DOI: 10.1039/C5RA12742D
chloride1a and polyfluoroaniline (Scheme 1A).13a Structural and 4-methoxyphenyl boronic acid 4b as a model reaction (Table 1).
characterization showed that the complexes involved
a
Although the reaction was less effective or ineffective in a range of
molecule of DMF solvent. A control experiment revealed that aprotic polar solvents (entries 1–5), we found that complete
the reaction of stoichiometric amount of 3a with boronic acid conversion as well as high yield of the coupled product 7a could be
4a led to the formation of ortho-arylated product 5a in 93% obtained when the reaction was performed in non-polar toluene
yield under mild conditions (Scheme 1B). These observations (entry 6) and several alcoholic solvents such as tBuOH, iPrOH, and
indicated that the transmetalation of 3a with boronic acid 4a EtOH (entries 7–9) with 1 mol% loading of 3a in the presence of
o
and the followed reductive elimination, the last two steps of K2CO3 as base at 40 C. Next, the most readily affordable EtOH was
the Suzuki-Miyaura cross-coupling cycle, could readily proceed. chosen as solvent to further examine the efficacy of the complex. It
On the basis of this initial result, we conceived that, if the was found that the reaction proceeded very well at ambient
oxidative addition between the Pd(0) generated from the palladium temperature (entries 10 and 11). Moreover, an array of bases
complexes 3 and an aryl (pseudo)halide takes place facilely, the (entries 11–15) was also compatible for mild couplings except for
new palladacycle 3 can be used as a promising precatalyst for mild Li2CO3 (entry 13). Notably, the coupling could complete rapidly
Suzuki-Miyaura cross-coupling. Taking this consideration in mind, within two hours when K3PO4 was used as base (entry 15). The
reaction also proceeded efficiently in an aqueous medium although
the yield was slightly diminished (entry 16). In addition, the
palladacycle 3b displayed an equally good catalytic activity to 3a
(entry 17). These results indicate that the phosphinamide-based
Table 1 Evaluation of the catalytic activity of palladacycles 3a
palladacycles are active precatalysts for mild Suzuki-Miyaura
e
M
reaction. Most importantly, the complexes tolerate various solvents
and bases. These features represent the important advantages of a
catalyst since for transition-metal-catalyzed cross-couplings, it is
often observed that a catalyst which is effective under a set of
conditions would become ineffective even by a minor change of the
parameters such as solvent, base, or ligand.14
O
e
M
r
B
Ph
P
R
ase
3
b
l
,
N
a
6
so ven
t
+
Pd
DMF
e
M
O
B H
O
( )
2
a .
t 3
C
e
It is also noteworthy that the catalytic activity of the pallada-
cycles was entirely maintained after by storing the complex in a
flask for over 8 months under an ambient atmosphere (entries 18
and 19). Moreover, almost identical yield (92%) was obtained when
the reaction was scaled up to 10 mmol. These results
unambiguously exemplified that the complexes 3 exhibit excellent
stability against the erosion of lab atmosphere. Finally, the catalysts
can be very easily prepared via a two-step procedure from
inexpensive diphenylphosphinic chloride 1a and do not need
further activation with electron-rich or sterically bulk ligands. As a
result, the stability and cheapness may be added bonus of the
complexes 3 for practical applications.
Thus, an comprehensive evaluation on various reaction
parameters through the model reaction demonstated that the
phosphinamide-derived palladacycles 3 could serve as a practical
precatalyst for mild Suzuki-Miyaura cross-couplings. Next, to
examine the generality, a rich range of arylbromides were subjected
to react with an array of aryl boronic acids under the standard
conditions (Table 1, entry 15). The reactions proceeded very well
for both coupling partners decorated by electron-neutral, -rich, and
-deficient substitutents (Table 2, 7a–7n). In most cases, excellent
yields could be obtained for a wide variety of combiantions of aryl
bromides with boronic acids. Moreover, almost identical reaction
efficiency was observed under nitrogen and air atmosphere. In
addition, the ring-fused aromatic bromide could be coupled
smoothly under the conditions (7o–7r). Notably, the 2,6-
disubstituted aryl bromides were also viable substrates (7s and 7t)
although a 2 mol% catalyst loading and a slightly elevated
temperature were needed for these sterically hindered compounds.
Of note, the coupling occurred exclusively at the bromide position
for 1-bromo-4-chlorobenzene (7l–7n). These results indicate that
M
4b
O
=
-
R
F5
C6
F
F4
C
3C6
,
p
a
7
Cat.
T
T
Yield
Base
Solvent
Entry
(oC)
(%)b
(mol%)
(h)
1
2
3
4
5
6
7
8
9
3a (0.5)
3a (1.0)
3a (1.0)
3a (1.0)
3a (1.0)
3a (1.0)
3a (1.0)
3a (1.0)
3a (1.0)
3a (1.0)
3a (1.0)
3a (1.0)
3a (1.0)
3a (1.0)
3a (1.0)
3a (1.0)
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
Na2CO3
Li2CO3
CsF
K3PO4
K3PO4
DMF
DMF
dioxane
MeCN
THF
toluene
tBuOH
iPrOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH/
H2O
18
18
18
18
18
18
18
18
18
18
24
24
24
24
2
40
40
40
40
40
40
40
40
40
rt
rt
rt
rt
rt
rt
rt
53
66
40
24
5
90
84
83
90
87
90
90
40
94
94
71
10c
11
12
13
14
15
16d
2
17
18e
19e,f
3b (1.0)
3a (1.0)
3a (1.0)
K3PO4
K3PO4
K3PO4
EtOH
EtOH
EtOH
2
2
2
rt
rt
rt
94
96
93
a The reaction conditions are: 6a (0.5 mmol), 4b (0.75 mmol, 1.5
equiv), 3 (1 mol%), base (1.5 mmol, 3.0 equiv) in solvent (3 mL)
under nitrogen atmosphere. Isolated yield. rt stands for the
ambient temperature ranging from 20 to 25 oC. d EtOH/H2O = 1:1 in
volume. e The reaction was run under air atmosphere. f The reaction
was carried out by storing 3a in a flask for over 8 months.
b
c
2 | J. Name., 2012, 00, 1-3
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Table 2 The substrate scope of aryl bromides and boronic acidsa
Table 3 The coupling of polyfluorophenyl boronic acidVsiaew Article Online
DOI: 10.1039/C5RA12742D
mo
a
3
%
Fn
mo
a
3
1
l
1
l
%
R
Fn
R
R'
R'
R
R
r
B
+
B
O
(
H
K P
O4
K P
O4
)
2
3
3
r
B +
H
2B
)
O
(
r
H
t
,
Et
O
r
H
t
,
Et
O
6
8
10
6
7
4
F
F
F
tBu
OMe
Me
F
F
F
F
Me
Me
Me
MeO2C
MeO
MeO
7a
7c
7b
10a
10c
10b
2
2
2
94%
96%b
92%b,c
h,
h,
h,
8
80%
6
5
98%
h,
10
h,
5
97%
h,
5
95%
2
2
94%
94%b
F
h,
h,
h,
78%b
b
h,
h,96%
F
Me
CN
tBu
F
F
F
F
F
F
Me
MeO
18
MeO
7f
7d
7e
MeO2C
10e
10f
87%
85%b
10d
h,
h,
10
10
10 95%
h,
91%
h,
h,
5
93%
2
h,
94%
2
96%
h,
88%b
95%b
h,
12
8
h,
tBu
CN
OMe
a The reaction conditions were: 6 (0.5 mmol), 8 (0.75 mmol, 1.5
equiv), 3a (1 mol%), K3PO4 (1.5 mmol, 3.0 equiv) in EtOH (3 mL) at rt
for 2–5 h under air atmosphere; isolated yield; the reaction time
was not optimized. b The reactions were performed under nitrogen
atmosphere.
MeO
MeO2C
MeO2C
CN
7i
7h
7g
5
5
10
10
96%
80%
h,
h,
h,
h,
6 h
3
96%
97%b
71%b
85%b
h,
Me
OMe
Nevertheless, the results provide a useful way for the othogonal
modification of multihalogen-substituted benzenes.
MeO2C
Cl
MeO2C
7l
7k
7j
88%d
h,
h,
6
6
96%
92%b
6
6
h,
h,
4
90%
87%b
h,
h,
Having demonstrated the highly catalytic activity of 3a for
coupling aryl bromides with a range of common phenyl boronic
acids, we examined its catalytic efficiency for coupling the
polyfluorophenyl (8) (Table 3) and 2-heterocyclicboronic acids (9)
(Table 4). As mentioned, the coupling of these two types of
nucleophiles remains problematic under most of the conventional
conditions. Here, we found that while the reaction was ineffective
for the more electron-deficient 2,6-difluorophenyl boronic acid
presumably due to the fast protodeboronation, complete
conversion as well as excellent yields were observed for the
reaction of 3,5-difluoro and 3,4,5-trifluorophenyl boronic acids. The
electron-rich (10a and 10b), deficient (10c and 10d), and the ring-
fused (10e and 10f) aryl bromides were compatible. In addition, a
range of O- and S-containing 2-heteroaromatic boronic acids were
also viable substrates (11a–11r in Table 4). Although the catalytic
activity was somewhat decreased for 2-heterocyclic boronic acids as
compared with the common aryl brononic acids, high to excellent
yields could be obtained by performing the reaction with the
presence of 2 mol% of 3a or by elevating the reaction temperature
88%b,d
8
tBu
OMe
CN
Cl
Cl
7o
7n
7m
12
1
6
6
90%
93%
82%b
4
4
96%
88%b
h,
h,
h,
90%b
h,
h,
h,
tBu
CN
Me
7r
7p
7q
12
12
86%
87%b
12
6
88%
h,
h,
h,
6 h
6
76%
79%b
,
87%b
h,
h,
tBu
OMe
Me
Me
Me
Me
80%e
7s 12
79%e,f
7t 12
h,
h,
a The reaction conditions: 6 (0.5 mmol), 4 (0.75 mmol, 1.5 equiv), 3a
(1 mol%), K3PO4 (1.5 mmol, 3.0 equiv) in EtOH (3 mL) at rt under
nitrogen; isolated yield; the reaction time was not optimized. The
reactions were performed under air atmosphere. 6a (10 mmol),
o
to 50 C under nitrogen atmosphere. Moreover, a broad variety of
b
functional groups such as methoxy, ester, aldehyde, nitro, and
chloride groups were well tolerated. Unfortunately, a preliminary
trial showed that the conditions were ineffective for a N-Boc
protected indol-2-yl boronic acid. The reasons await detailed
investigation.
Next, we investigated the reaction of the aryl triflate
electrophiles (Table 5). Among the transition-metal-catalyzed cross-
couplings of phenolic derivatives, the aryl triflates are attactive
substrates due to the high reactivity. However, their instability
c
4b (15 mmol, 1.5 equiv), 3a (1 mol%), K3PO4 (30 mmol, 3.0 equiv) in
EtOH (60 mL) at rt for 1.5 h. d The methyl ester group of the product
e
was partially exchanged to ethyl ester. The reaction was run with
o
f
the presence of 2 mol% 3a at 50 C under nitrogen atmosphere.
The yield was determined based on the 1H-NMR spectroscopic
analysis due to the contamination of a small amount of inseparable
by-product from the homocoupling of boronic acid.
the precatalyst was less effective for the inert aryl chlorides.
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Table 4 The coupling of 2-heterocyclic boronic acidsa
Table 5 The coupling of aryl triflatesa
View Article Online
DOI: 10.1039/C5RA12742D
a
3
a
mo
1 l
%
mo
1
l
3
%
,
R
R
r
B
+
R
B
O
(
H
K P
O4
R
K P
O4
)
2
3
3
r
A
r
A
X
O S
,
X
B
H
)
2
Tf +
O
O
(
r
Et H
t
O
,
r
H
t
,
Et
O
=
X
or
9
6
4
11
or
7
11
9
12
OMe
CO2Me
OMe
X
O
NC
RO2C
MeO
7u
7o
7g
h,
11a
=
=
11b X
R
5
97%
O,
S,
Me, h,
1
87%
12
8
96%
h,
95%b
12
8
50%b
96%
h,
97%b
97%b
82%c
6
h,
6
h,
h,
h,
=
=
Et,
11c X
R
12
h,
OMe
CO2Me
OMe
X
X
O
F
Ph
Ph
N
O2
7w
7x
=
=
7v
11d X
11e X
12
h,
12
h,
96%
70%c
O,
S,
=
11f X
6
94%
O, h,
12
97%c
4
8
8
94%
95%b
91%
8
4
h,
h,
95%
94%b
h,
h,
=
h,
h,
X
S,
h,
11g
93%b
4
OMe
OMe
CO2Me
X
X
O
EtO2C
91%c
60%c
Cl
=
11k
11l
X
12
h,
24
h,
=
O,
11h
X
6
95%
O, h,
12
H
O
Me
6
6
90%
h,
h,
11j
80%d
=
X
=
S,
F
89%b
11i
X
S,
h,
7z
7aa
7y
91%
93%b,c
O
12
78%
h,
2
90%
6
6
h,
h,
h,
X
X
X
O
CO2Me
N
O2
76%c
94%d
89%c
98%d
85%c
=
11m
11n
X
12
h,
12
h,
=
=
O,
11o
11p
X
X
6
X
12
O, h,
6
11q
11r
O,
24
h,
70%c,e
h,
O
=
O
X
=
S,
X=
S,
h,
S,
Me
NC
a The reaction conditions were: 6 (0.5 mmol), 9 (0.75 mmol, 1.5
equiv), 3a (1 mol%), K3PO4 (1.5 mmol, 3.0 equiv) in EtOH (3 mL)
7ab
11h
11s
O
86%c
12
76%
4
h,
91%
h,
6
h,
at rt for 5–24 h under nitrogen atmosphere; isolated yield; the
a
b
The reaction conditions were: Aryl triflates 12 (0.5 mmol),
reaction time was not optimized.
The reactions were
performed under air atmosphere. c The ractions were performed
in the presence of 2 mol% of 3a at 50 oC. Under these
conditions, the methyl ester group in methyl 4-bromobenzoate
substrate was exchanged to ethyl ester in the products 11c, 11k,
boronic acids 4 or 9 (0.75 mmol, 1.5 equiv), 3a (1 mol%), K3PO4
(1.5 mmol, 3.0 equiv) in EtOH (3 mL) at rt for 1–12 h under
nitrogen atmosphere; isolated yield; the reaction time was not
optimized. Yields were obtained under air atmosphere. The
methyl ester group of the product was partially exchanged to
ethyl ester.
b
c
d
and 11l. The reactions were performed in the presence of 2
o
e
mol% of 3a at 50 C in DMF solvent. Cs2CO3 instead of K3PO4
was used as base in DMF at 50 oC.
clear evidence to confirm the formation of palladium nanoparticles.
makes this reaction troublesome. Especially, the decomposition of In addition, the arylated product 5a (Scheme 1) could also be
electron-deficient aryl triflates is often occured when protic detected. These results together with our previous reports13a
solvents such as water or alcohols are used, although a indicates that the generation of Pd(0) may proceed through the
heterogeneous Pd/C-catalyzed effective coupling of electron- transmetallation of palladacycle 3 and boronic acids followed by the
deficient aryl triflates in aqueous media has been reported.7a Here, reductive elimination of Pd(II).
we demonstrated that with the presence of 1 mol% of 3a, a wide
array of electron-deficient aryl triflates underwent smooth coupling
with various boronic acids including electron-rich and deficient, as
Conclusions
well as 2-heterocyclic boronic acids to afford the coupled products
in high to excellent yield at room temperature and under nitrogen
or air atmosphere.
In conclusion, we have demonstrated that the unprecedented
palladacycles derived from phosphinamide are a type of practical
precatalysts for mild Suzuki-Miyaura cross-coupling of aryl
bromides and triflates attributed to their prominent overall
performance such as high activity, easy preparation, excellent
stability, and broad compatibility for various reaction parameters. A
Concerning the catalytic mechanism of the cyclic palladium
complexes 3, it should proceed via a conventional Pd(0) to Pd(II) cycle
since palladium black was observed during the reaction, although
analysis by transmission-electron-microscopy (TEM) did not provide
4 | J. Name., 2012, 00, 1-3
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Herrmann, Angew. Chem. Int. Ed.,2002, 41, 1363; (g) G.
wide variety of electrophiles and nucleophiles could be cross-
coupled efficiently with the presence of 1 mol% of pallacycles at
ambient temperature and under air atmosphere. More important
implications beyond this work are that the results presented herein
would provide useful clues for further design of new catalysts and
development of new reactions. Some of these works are currently
underway in our lab.
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Altenhoff, R. Goddard, C. W. LehmannDaOnId: 1F0..1G0l3o9r/iCus5,RAA1n2g74e2wD.
Chem. Int. Ed.,2003, 42, 3690; (h) F. X. Roca and C. J.
Richards, Chem. Commun.,2003, 3002; (i) O. Navarro, R. A.
Kelly III and S. P. Nolan, J. Am. Chem. Soc.,2003, 125, 16194;
(j) O. Navarro, N. Marion, Y. Oonishi, R. A. Kelly III and S. P.
Nolan, J. Org. Chem.,2006, 71, 685; k) Z. Liu, T. Zhang and M.
Shi, Organometallics,2008, 27, 2668.
6
7
For selected publications of Ni-catalyzed mild couplings, see:
(a) Z.-Y. Tang and Q.-S. Hu, J. Am. Chem. Soc.,2004, 126, 3058;
(b) P. Leowanawat, N. Zhang, A.-M. Resmerita, B. M. Rosen
and V. Percec, J. Org. Chem.,2011, 76, 9946.
For selected examples, see: (a) T. Maegawa, Y. Kitamura, S.
Sako, T. Udzu, A. Sakurai, A. Tanaka, Y. Kobayashi, K. Endo, T.
Kurita, A. Kozaki, Y. Monguchi and H. Sajiki, Chem, Eur. J.,
2007, 13, 5937; (b) O. Navarro, R. A. Kelly, III and S. P. Nolan,
J. Am. Chem. Soc., 2003, 125, 16194; (c) D. Zim, A. S. Gruber,
Experimental Section
General procedure for cross-coupling under nitrogen atmosphere:
To a Schlenk tube equipped with a magnetic bar was charged solid
aryl bromide or triflate (0.5 mmol), boronic acid (0.75 mmol), 3a (1
mol%), anhydrous K3PO4 (1.5 mmol). The tube was then evacuated
under vacuum and backfilled with N2. EtOH (3.0 mL) was injected
via syringe (the aryl bromide or triflate (0.5 mmol) was also added
at this stage if it is liquid). The reaction mixture was stirred at rt or
50 oC until the arylbromidesor triflates had disappeared as
monitored by TLC. The reaction mixture was poured into water (30
mL) and then extracted with CH2Cl2 (20 mL × 3). The combined
organic layer was dried over anhydrous Na2SO4, filtered, and
concentrated to dryness. Thecrude material was purified by flash
chromatography on silica gel using a mixture of hexane and CH2Cl2
as eluents to give the desired cross-coupled product.
G. Ebeling, J. Dupont and A. L. Monteiro, Org. Lett., 2010, 2,
2281.
8
9
For selected publications, see: (a) H. G. Kuivila, J. F. Reuwer
and J. A. Mangravite, J. Am. Chem. Soc., 1964, 86, 2666; (b) T.
E. Barder, S. D. Walker, J. R. Martinelli and S. L. Buchwald, J.
Am. Chem. Soc., 2005, 127, 4685; (c) K. Billingsley, K. W.
Anderson and S. L. Buchwald, Angew. Chem. Int. Ed., 2006,
45, 3484; (d) K. Billingsley and S. L. Buchwald, J. Am. Chem.
Soc., 2007, 129, 3358; (e) D. M. Knapp, E. P. Gillis and M. D.
Burke, J. Am. Chem. Soc., 2009, 131, 6961.
For selected publications, see: (a) Y. Dang and Y. Chen. J. Org.
Chem.,2007, 72, 6901; (b) H. Maeda, Y. Haketa and T.
Nakanishi, J. Am. Chem. Soc.,2007, 129, 13661; (c) G. S. Gill,
D. W. Grobelny, J. H. Chaplin and B. L. Flynn, J. Org.
Chem.,2008, 73, 1131; (d) M. G. Organ, S. Calimsiz, M. Sayah,
Acknowledgements
K. H. Hoi and A. J. Lough, Angew. Chem. Int. Ed.,2009, 48
,
2383; (e) C. A. James, A. L. Coelho, M. Gevaert, P. Forgione
and V. Snieckus, J. Org. Chem.,2009, 74, 4094; (f) B. Bhayana,
B. P. Fors and S. L. Buchwald, Org. Lett.,2009, 11, 3954; (g)
G.-R. Peh, E. A. B. Kantchev, J.-C. Er and J. Y. Ying, Chem. Eur.
J.,2010, 16, 4010; (h) G. A. Molander and F. Beaumard, Org.
Lett.,2010, 12, 4022.
Financial support from NSFC (21272225) and the State Key
Laboratory of Fine Chemicals (KF1201) is acknowledged.
Notes and references
10 T. Kinzel, Y. Zhang and S. L. Buchwald, J. Am. Chem. Soc.,
2010, 132, 14073.
1
2
N. Miyaura and A. Suzuki, Chem. Rev.,1995, 95, 2457.
For selected recent reviews, see: (a) R. Martin and S. L.
Buchwald, Acc. Chem. Res.,2008, 41, 1461; (b) R. Jana, T. P.
Pathak and M. S. Sigman, Chem. Rev.,2011, 111, 1417; (c) A.
Fihri, M. Bouhrara, B. Nekoueishahraki, J.-M. Basset and V.
Polshettiwar, Chem. Soc. Rev.,2011, 40, 5181; (d) C. Valente,
S. Çalimsiz, K. H. Hoi, D. Mallik, M. Sayah and M. G. Organ,
Angew. Chem. Int. Ed.,2012, 51, 3314.
11 For some selected comments and investigations concerning
the stability of arene triflates, see: (a) J. P. Wolfe, H. Tomori,
J. P. Sadighi, J. Yin and S. L. Buchwald, J. Org. Chem., 2000, 65
1158; (b) A. L. Hansen, J.-P. Ebran, T. M. Gøgsig and T.
Skrydstrup, J. Org. Chem., 2007, 72, 6464; (c) J. Albaneze-
Walker, R. Raju, J. A. Vance, A. J. Goodman, M. R. Reeder, J.
Liao, M. T. Maust, P. A. Irish, P. Espino and D. R. Andrews,
Org. Lett., 2009, 11, 1463.
,
3
For selected recent review, see: (a) D.-G. Yu, B.-J. Li and Z.-J.
Shi, Acc. Chem. Res.,2010, 43, 1486; (b) B. M. Rosen, K. W.
Quasdorf, D. A. Wilson, N. Zhang, A.-M. Resmerita, N. K. Garg
and V. Percec, Chem. Rev.,2011, 111, 1346; (c) B.-J. Li, D.-G.
Yu, C.-L. Sun and Z.-J. Shi, Chem. Eur. J.,2011, 17, 1728; (d) T.
Mesganaw and N. K. Garg, Org. Process Res. Dev.,2013, 17
29; (e) F.-S. Han, Chem. Soc. Rev.,2013, 42, 5270.
12 (a) Y.-L. Zhao, Y. Li, Y. Li, L.-X. Gao and F.-S. Han, Chem. Eur. J.,
2010, 16, 4991; (b) G.-J. Chen, J. Huang, L.-X. Gao and F.-S.
Han, Chem. Eur. J., 2011, 17, 4038; (c) S.-M. Li, J. Huang, G.-J.
Chen and F.-S. Han, Chem. Commun., 2011, 47, 12840; (d) H.
Gao, Y. Li, Y.-G. Zhou, F.-S. Han and Y.-J. Lin, Adv. Synth.
Catal., 2011, 353, 309; (e) Y.-L. Zhao, Y. Li, S.-M. Li, Y.-G. Zhou,
F.-Y. Sun, L.-X. Gao and F.-S. Han, Adv. Synth. Catal., 2011,
353, 1543; (f) G.-J. Chen and F.-S. Han, Eur. J. Org. Chem.,
2012, 3575.
,
4
5
For a recent review concerning the industrial applications of
Pd-catalyzed coupling reactions, see: C. Torborg and M.
Beller, Adv. Synth. Catal.,2009, 351, 3027; and related
references therein.
13 (a) J. Guan, G.-J. Wu and F.-S. Han, Chem. Eur. J.,2014, 20
,
For selected publications of palladium-catalyzed mild
couplings, see ref. 4g, 7, and (a) J. P. Wolfe, R. A. Singer, B. H.
Yang and S. L. Buchwald, J. Am. Chem. Soc.,1999, 121, 9550;
(b) A. F. Littke, C. Dai and G. C. Fu, J. Am. Chem. Soc.,2000,
122, 4020; (c) D. Zim, A. S. Gruber, G. Ebeling, J. Dupont and
3301; (b) J. Guan, G.-J. Wu and F.-S. Han, Chin. J. Appl.
Chem.,2014, 31, 1280; (c) Z.-J. Du, J. Guan, G.-J. Wu, P. Xu, L-
X. Gao and F.-S. Han, J. Am. Chem. Soc., 2015, 137, 632.
14 For selected examples, see: (a) V. Percec, G. M. Golding, J.
Smidrkal and O. Weichold, J. Org. Chem., 2004, 69, 3447; and
references therein; (b) X. Huang, K. W. Anderson, D. Zim, L.
Jiang, A. Klapars and S. L. Buchwald, J. Am. Chem. Soc., 2003,
125, 6653.
A. L. Monteiro, Org. Lett.,2000, 2, 2881; (d) N. Kataoka, Q.
Shelby, J. P. Stambuli and J. F. Hartwig, J. Org. Chem.,2002,
67, 5553; (e) J. P. Stambuli, R. Kuwano and J. F. Hartwig,
Angew. Chem. Int. Ed.,2002, 41, 4746; (f) C. W. K. Gstöttmayr,
V. P. M. Böhn, E. Herdtweck, M. Grosche and W. A.
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DOI: 10.1039/C5RA12742D
Table of Content
We present the arylphosphinamide-derived palladacyclic
complexes (See Scheme) which could be used as efficient
and versatile precatalysts for mild Suzuki-Miyaura cross-
coupling.
O
Ph
R
Cat. (1 mol%)
K3PO4
P
R
R
N
+
(HO)2B Ar
X
EtOH, rt, air
Pd
Ar = common aryl
polyfluoro aryl
2-heterocyclic
X = Br, OTf
Ar
Cat. DMF
R = C6F5 or
p-CF3C6F4
6 | J. Name., 2012, 00, 1-3
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