Copper-catalyzed C-N cross-coupling of substituted 2-halobenzoates with secondary acyclic amides

Article abstract of DOI:10.1055/s-0033-1338800

The copper-catalyzed C-N cross-coupling of poorly nucleophilic acyclic secondary amides with sterically hindered substituted 2-halobenzoates has been demonstrated with 1,4-dimethyl-3,4-dihydro-1H-benzo[e][1,4]diazepin-5(2H)-one (DMBDO) as ligands for the first time. The protocol is effective for the synthesis of hindered tertiary amides. We also found that the alkoxycarbonyl (CO₂R) group has a strong ortho-substituent effect on a Goldberg-type C-N coupling reaction. Georg Thieme Verlag Stuttgart. New York.

Full text of DOI:10.1055/s-0033-1338800

PAPER
▌A
paper
Copper-Catalyzed C–N Cross-Coupling of Substituted 2-Halobenzoates with
Secondary Acyclic Amides
N-Arylation of Secondary Acyclic Amides
Man-Gang Wang, Hua Yu, Jun Wu,* Zhi-Cai Shang*
Department of Chemistry, Zhejiang University, Hangzhou 310027, P. R. of China
Fax +86(571)87951895; E-mail: shangzc@zju.edu.cn
Received: 10.01.2013; Accepted after revision: 17.04.2013
Our initial investigation was based on the reaction of N-
Abstract: The copper-catalyzed C–N cross-coupling of poorly nu-
phenylbenzamide (1a) with methyl 2-iodobenzoate (2a)
cleophilic acyclic secondary amides with sterically hindered substi-
in the presence of 20 mol% of copper(II) bromide in tolu-
ene at 130 °C under air (Table 1). With cesium carbonate
tuted 2-halobenzoates has been demonstrated with 1,4-dimethyl-
3,4-dihydro-1H-benzo[e][1,4]diazepin-5(2H)-one (DMBDO) as li-
gands for the first time. The protocol is effective for the synthesis of as base, the reaction was observed to give the product
hindered tertiary amides. We also found that the alkoxycarbonyl
(CO2R) group has a strong ortho-substituent effect on a Goldberg-
type C–N coupling reaction.
methyl 2-(N-phenylbenzamido)benzoate (3a) in 35%
yield after 24 hours in the presence of 40 mol% N,N′-di-
methylethylenediamine (DMEDA; entry 1). The structure
Key words: copper, N-arylation, cross-coupling, amides, haloben-
zoates
of the products was confirmed by an X-ray single-crystal
diffraction analysis of 3a (Figure 1).14 After screening of
various bases and solvents, it was observed that potassium
carbonate and xylene are effective for this reaction (en-
The amide moiety is an important structural motif in a
great number of biologically active compounds and func-
tional molecules.1 Copper-catalyzed C–N cross-coupling
reactions are among the most powerful and versatile tools
to construct this structural motif. However, the classic
Ullmann reaction2 and the related Goldberg reaction3 of-
ten require drastic reaction conditions, for example, stoi-
chiometric amounts of copper salts, high temperatures
(>150 °C), and the use of polar solvents such as N,N-di-
methylformamide, collidine, and pyridine. In the past few
years, a wide range of ligands, including diamines,4
diimines,5 amino acids,6 β-keto esters,7 ethylene glycols,8
heptadiones,9 xantphos, or Xphos10 have been exploited
for these catalytic processes in the presence of catalytic
amounts of the copper or palladium catalysts. Although
these processes display increased activity and substrate
scope relative to their predecessors, a significant limita-
tion to these processes is that they are mostly restricted to
primary amides or lactams, and the use of ortho-substitut-
ed coupling partners in intermolecular reactions is rare.
For secondary acyclic amides (which are known to be
challenging cross-coupling substrates due to their steric
hindrance10a and poor nucleophilicity11) or sterically hin-
dered coupling partners, only a few isolated examples in-
volving either palladium or copper as catalysts have been
described until recently.9,10a,b,11,12 In continuation of our
endeavors devoted to the development of copper-cata-
lyzed coupling reactions,13 herein we wish to report a cop-
per-catalyzed C–N cross-coupling reaction of secondary
acyclic amides with sterically hindered 2-halobenzoates,
for which 1,4-dimethyl-3,4-dihydro-1H-benzo[e][1,4]di-
azepin-5(2H)-one (DMBDO) has been used as a ligand
for the first time.
tries 2 and 3). Encouraged by these results, we screened a
series of common ligands including N,N,N′,N′-tetrameth-
ylethylenediamine, triphenylphosphine, L-proline, and
picolinic acid. However, they all led to lower yields
(entries 4–7). Finally, we were pleased to find that the use
of 1,4-dimethyl-3,4-dihydro-1H-benzo[e][1,4]diazepin-
5(2H)-one (DMBDO) furnished a good isolated yield of
coupling product 3a (entry 8). Further studies revealed
that copper(I) iodide exhibited superior catalytic efficien-
cy compared to the other examined copper catalysts (en-
tries 9–11). The catalyst loading could be decreased to 10
mol% without any loss in yield (entry 12), and it could be
further decreased to 5 mol% with a slightly decreased
yield (entry 13). It is noteworthy that the reaction gave a
slightly lower yield under nitrogen atmosphere as com-
pared to air atmosphere (entry 15). Control experiments
revealed that no 3a was obtained in the absence of a cop-
per catalyst (entry 16) and the reaction was very sluggish
in the absence of a ligand (entry 17). Additionally, the
base potassium phosphate and the solvent dioxane, al-
though suitable for numerous N-arylation reactions,15 are
less effective under our reaction conditions (entry 18). Af-
ter optimization of the reaction conditions, the following
conditions were selected as the standard ones: amide 1
(0.25 mmol), 2-halobenzoate 2 (0.5 mmol), copper(I) io-
dide (0.025 mmol), ligand L6 (0.05 mmol), and potassium
carbonate (3 equiv) in xylene (2 mL) at 130 °C for 24
hours in the presence of air.
A number of N-arylbenzamides could be coupled by using
this methodology (Table 2). Coupling of substrates bear-
ing methoxy and methyl substituents is efficient (entries
1–3), whereas stronger electron-withdrawing substituents
are not tolerated (entry 4). A number of halogenated ben-
zamides reacted with methyl 2-iodobenzoate (2a) to give
the tertiary acyclic amides in good yields (entries 5–8).
These groups can facilitate subsequent chemoselective
processes. It was also noted that sterically hindered sec-
SYNTHESIS 2013, 45, 000A–000J
Advanced online publication: 05.06.2013
0
0
3
9
-
7
8
8
1
1
4
3
7
-
2
1
0
X
DOI: 10.1055/s-0033-1338800; Art ID: SS-2013-H0032-OP
© Georg Thieme Verlag Stuttgart · New York

B
M.-G. Wang et al.
PAPER
Table 1 Optimization of Reaction Conditionsa
MeOOC
Ph
I
Ph
N
NH
Cu, ligand
O
+
base, solvent
MeOOC
O
Ph
1a
2a
Ph
3a
Me Me
Me NH HN Me
L1
Me
N
N
Me
N
COOH
N
COOH
H
L2
L3
L4
Me
N
Ph
Ph
P
N
Me
Ph
O
L6
Figure 1 ORTEP representation of the crystal structure of 3a
L5
Entry Cu cat. (mol%) Ligand Solvent
Base
Yieldb (%)
ly better yields, except with the starting compound
derived from 4-nitrobenzoic acid (entry 14). Thus, we
were able to perform the coupling of N-arylarylamides
substituted with electron-donating or electron-withdraw-
ing groups on the aromatic rings (entries 15 and 16). The
cross-coupling reaction was also extended to an N-alkyl-
arylamide (entry 17) and N-arylacetamide (entry 18) with
2-halobenzoates, the corresponding coupling products be-
ing obtained in good isolated yields. In the case of N-(2-
chlorophenyl)benzamide (entry 8), coupling with 2a gave
a mixture of two stereoisomeric tertiary amides, as dem-
onstrated by NMR spectroscopy of 3i under different tem-
peratures.14 The products 3j, 3n and 3s (entries 9, 13, 18)
also were isomer mixtures. The slower rate of configura-
tional change may derive from rotational barriers in these
compounds.
1
2
CuBr2 (20)
CuBr2 (20)
CuBr2 (20)
CuBr2 (20)
CuBr2 (20)
CuBr2 (20)
CuBr2 (20)
CuBr2 (20)
CuI (20)
L1
L1
L1
L2
L3
L4
L5
L6
L6
L6
L6
L6
L6
L6
L6
L6
none
L6
toluene
DMF
Cs2CO3 35
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K3PO4
22
70
37
68
49
64
75
84
19
0
3
xylene
xylene
xylene
xylene
xylene
xylene
xylene
xylene
xylene
xylene
xylene
xylene
xylene
xylene
xylene
dioxane
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
CuCl (20)
CuO (20)
CuI (10)
The reaction scope was also studied with respect to differ-
ent substituted 2-halobenzoates, and the results are sum-
marized in Table 3. Among the three methyl 2-
halobenzoates (X = I, Br, Cl), methyl 2-iodobenzoate
showed the best results, affording methyl 2-(N-phenyl-
benzamido)benzoate in excellent yield, whereas methyl 2-
chlorobenzoate failed to give the desired products under
the standard conditions (entries 1–3). Good isolated yields
of the desired coupling products could be obtained when
ethyl 2-iodobenzoate (entry 4), cyclohexyl 2-iodobenzo-
ate (entry 5), and butyl 2-iodobenzoate (entry 6) were
used as the electrophiles. It indicated that the steric hin-
drance of the ester functional groups have little effect on
the reaction. Moreover, substituted 2-halobenzoates were
also tolerated (entry 7).
85
78
29c
79d
0
CuI (5)
CuI (10)
CuI (10)
none
CuI (10)
<5
55
CuI (10)
a Reaction conditions: 1a (0.25 mmol), 2a (0.5 mmol), base (3 equiv),
cat., solvent (2 mL), 130 °C, 24 h, under air.
b Isolated yield.
c Reaction run at 130 °C for 8 h.
d Under N2 atmosphere.
When meta- and para-substituted halobenzoates were
used (methyl 3-iodobenzoate and methyl 4-iodobenzo-
ate), low yields of corresponding coupling products were
obtained (35% and 39% respectively). It indicated that the
ortho ester functional groups have an accelerating effect
on the reaction. The proposed mechanism, based on the
above date and previous literature,16 is shown in Scheme
1. First, the copper(I) species A coordinates to the carbon-
yl group of 2; this is followed by oxidative addition to
give a copper(III)–aryl species B, just as illustrated by Ma
ondary acyclic amides are tolerated under these reaction
conditions (entries 8 and 9). Next we examined the effect
of the benzamide group on the efficiency of the reaction.
Both electron-rich and electron-deficient amide groups
were well tolerated, leading to excellent isolated yields of
the desired products (entries 10–14). In contrast to elec-
tron-rich groups, electron-deficient substrates gave slight-
Synthesis 2013, 45, A–J
© Georg Thieme Verlag Stuttgart · New York

PAPER
N-Arylation of Secondary Acyclic Amides
C
for similar copper-catalyzed C–O coupling reactions.16e the expected compound 3 and regenerate the catalytic
After reaction of B with amide 1 and base to give a cop- copper(I) species A in the process.
per(III) complex C, reductive elimination occurs to afford
Table 2 N-Arylation of Various Amides with Methyl 2-Iodobenzoatea
R1
MeOOC
R1
MeOOC
I
NH
CuI (10 mol%), L6 (20 mol%)
O
N
+
xylene, K2CO3 (3 equiv)
130 °C
R2
O
R2
1
2a
3
Entry
1
3
Yield (%)b
O
O
N
1
3b
81
N
H
COOMe
OMe
O
OMe
O
N
2
3
3c
93
68
N
H
COOMe
O
O
O
O
O
O
N
3d
N
H
COOMe
NO2
O
O
O
O
NO2
N
N
N
N
4
5
6
7
3e
0
N
H
COOMe
Br
Br
3f
88
83
87
N
H
COOMe
Cl
Cl
3g
N
H
COOMe
F
F
3h
N
H
COOMe
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2013, 45, A–J

D
M.-G. Wang et al.
PAPER
Table 2 N-Arylation of Various Amides with Methyl 2-Iodobenzoatea (continued)
R1
MeOOC
R1
MeOOC
I
NH
CuI (10 mol%), L6 (20 mol%)
O
N
+
xylene, K2CO3 (3 equiv)
130 °C
R2
O
R2
1
2a
3
Entry
1
3
Yield (%)b
Cl
O
Cl
O
N
8
3i
37
N
COOMe
H
O
O
9
3j
60
N
O
N
H
COOMe
O
N
10
11
12
13
14
3k
3l
75
68
85
77
59
N
H
COOMe
O
O
N
N
H
COOMe
O
O
N
N
3m
3n
3o
COOMe
H
Br
Br
Cl
O
Cl
O
N
N
H
COOMe
O
O
N
N
COOMe
H
O2N
O2N
OMe
O
OMe
O
N
15
3p
78
N
COOMe
H
Br
Br
Synthesis 2013, 45, A–J
© Georg Thieme Verlag Stuttgart · New York

PAPER
N-Arylation of Secondary Acyclic Amides
E
Table 2 N-Arylation of Various Amides with Methyl 2-Iodobenzoatea (continued)
R1
MeOOC
R1
MeOOC
I
NH
CuI (10 mol%), L6 (20 mol%)
O
N
+
xylene, K2CO3 (3 equiv)
130 °C
R2
O
R2
1
2a
3
Entry
1
3
Yield (%)b
Br
O
Br
O
N
16
3q
68
N
H
COOMe
O
O
Me
N
Me
N
H
17
18
3r
3s
70
80
COOMe
O
O
N
COOMe
N
H
a Reaction conditions: 1 (0.25 mmol), 2a (0.5 mmol), base (3 equiv), CuI (0.025 mmol), L (0.05 mmol), xylene (2 mL), 130 °C, 24 h, under air.
b Yields of isolated products after chromatographic purification.
Table 3 The Reaction Scope for the Synthesis of 2-Halobenzoatesa
X
R1
Ph
R1
NH
Ph
Ph
CuI (10 mol%), L6 (20 mol%)
+
R2
N
O
R2
xylene, K2CO3 (3 equiv)
130 °C
O
Ph
1a
2
3
Entry
2
3
Yield (%)b
O
O
O
I
N
N
N
COOMe
1
3a
85
COOMe
COOMe
COOMe
Br
COOMe
COOMe
2
3
3a
3a
64
Cl
0
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2013, 45, A–J

F
M.-G. Wang et al.
PAPER
Table 3 The Reaction Scope for the Synthesis of 2-Halobenzoatesa (continued)
X
R1
Ph
R1
NH
Ph
Ph
CuI (10 mol%), L6 (20 mol%)
+
R2
N
O
R2
xylene, K2CO3 (3 equiv)
130 °C
O
Ph
1a
2
3
Entry
2
3
Yield (%)b
O
O
O
O
I
N
N
N
N
COOEt
4
3t
80
COOEt
COOCy
COOBu
COOMe
I
COOCy
COOBu
5
6
3u
3v
80
83
I
Br
COOMe
7
3w
53
F
F
a Reaction conditions: 1a (0.25 mmol), 2 (0.5 mmol), base (3 equiv), CuI (0.025 mmol), L (0.05 mmol), xylene (2 mL), 130 °C, 24 h, under air.
b Yields of isolated products after chromatographic purification
benzoates. We also found that the CO2R group has a
strong ortho-substituent effect on the Goldberg-type C–N
MeOOC
R1
N
LCuIX
A
coupling reaction. This protocol provides a novel synthet-
ic route to an array of hindered tertiary amides, with inex-
pensive copper as the catalyst. Further efforts for the
applications of this catalytic system are ongoing in our
laboratory, along with further mechanistic studies.
MeOOC
X
O
R2
3
2
MeO
O
OMe
L
CuIII
All reactions were carried out under an air atmosphere in oven-dried
glassware with magnetic stirring. Unless otherwise noted, all mate-
rials were obtained from commercial suppliers and were used with-
out further purification. Amides9 and L617 were prepared according
to the reported procedures. All solvents were reagent grade. Dichlo-
romethane, toluene and xylene were freshly distilled from CaH2 pri-
or to use. DMF was dried over 4 Å molecular sieves overnight prior
to use. 1,4-Dioxane were freshly distilled from sodium/benzophe-
none under nitrogen prior to use. Unless otherwise noted, organic
extracts were dried with Na2SO4, filtered through a fritted glass fun-
nel, and concentrated with a rotary evaporator (20–30 mmHg).
Flash chromatography was performed with silica gel (200–300
mesh) using the mobile phase indicated. Unless otherwise noted,
NMR spectra were recorded for 1H NMR at 400 MHz or 500 MHz,
and 13C NMR at 100 MHz or 125 MHz using TMS as internal stan-
O
X
R2
X
CuIII
N
L
X
R1
R2
B
O
C
base +
O
HN
R1
1
Scheme 1 Proposed reaction mechanism
In conclusion, we have developed a C–N cross-coupling
method for the reaction of synthetically useful aromatic
and aliphatic secondary amides with substituted 2-halo-
Synthesis 2013, 45, A–J
© Georg Thieme Verlag Stuttgart · New York

PAPER
N-Arylation of Secondary Acyclic Amides
G
dard. Mass spectrometry data were collected on an HRMS-APCI
instrument or a low-resolution MS instrument using EI or ESI ion-
ization. Melting points were measured with a micro melting point
apparatus.
1H NMR (500 MHz, CDCl3): δ = 7.95 (d, J = 20.6 Hz, 1 H), 7.56–
7.37 (m, 3 H), 7.34–7.23 (m, 2 H), 7.19 (t, J = 7.5 Hz, 2 H), 7.16–
7.03 (m, 2 H), 6.95 (s, 3 H), 3.80 (s, 3 H), 2.24 (s, 3 H).
13C NMR (126 MHz, CDCl3): δ = 170.58, 166.42, 143.72, 143.22,
138.88, 135.98, 132.89, 131.04, 130.06, 129.05, 128.77, 128.62,
128.05, 127.73, 127.12, 126.72, 124.90, 52.35, 21.25.
ESI-MS: m/z = 346.0 [M + H]+.
HRMS (EI): m/z [M+] calcd for C22H19NO3: 345.1365; found:
2-Amidobenzoates 3 by N-Arylation of Secondary Acyclic Am-
ides 1; General Procedure
The 2-halobenzoate 2 (0.5 mmol, 2 equiv) was added under air to a
mixture of the amide 1 (0.25 mmol, 1 equiv), CuI (5 mg, 0.025
mmol, 10 mol%), K2CO3 (0.1 g, 0.75 mmol, 3 equiv), and L6 (0.05
mmol, 20 mol%) in anhyd xylene (2 mL) in a 25 mL reaction tube.
The tube was sealed and the mixture was allowed to stir electromag-
netically in an oil bath at 130 °C for 24 h. After the mixture had
cooled to r.t., H2O (10 mL) was added and the mixture was extract-
ed with EtOAc (3 × 20 mL). The combined organic phase was dried
(Na2SO4), filtered, and concentrated. The residue was purified by
flash column chromatography (silica gel, EtOAc–PE); this afforded
the corresponding product 3.
345.1368.
Methyl 2-[N-(4-Bromophenyl)benzamido]benzoate (3f)
Yield: 90.2 mg (88%); pale yellow solid; mp 153–155 °C.
IR (KBr): 1716, 1665, 1599, 1483, 1344, 1282, 1271, 813, 713, 622
cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.91 (s, 1 H), 7.46 (d, J = 6.7 Hz,
3 H), 7.31 (dd, J = 16.1, 8.3 Hz, 4 H), 7.22 (t, J = 7.4 Hz, 2 H), 7.11
(d, J = 7.8 Hz, 1 H), 7.04 (d, J = 20.2 Hz, 2 H), 3.79 (s, 3 H).
13C NMR (126 MHz, CDCl3): δ = 170.38, 166.14, 142.84, 137.98,
135.48, 133.09, 132.01, 131.30, 130.38, 129.03, 128.83, 127.95,
127.20, 119.70, 52.43.
Methyl 2-(N-Phenylbenzamido)benzoate (3a)
Yield: 70.3 mg (85%); white solid; mp 130–132 °C.
IR (KBr): 1726, 1662, 1598, 1489, 1455, 1337, 1283, 1087, 956,
760, 691, 620 cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.93 (s, 1 H), 7.47 (dd, J = 18.3,
7.4 Hz, 3 H), 7.36–7.02 (m, 10 H), 3.80 (s, 3 H).
13C NMR (126 MHz, CDCl3): δ = 170.6, 166.4, 143.8, 143.2, 135.9,
ESI-MS: m/z = 409.9 [M + H]+.
HRMS (EI): m/z [M+] calcd for C21H16BrNO3: 409.0314; found:
409.0314.
132.9, 131.1, 130.1, 129.1, 128.9, 127.8, 127.5, 126.8, 126.2, 52.4.
ESI-MS: m/z = 332.0 [M + H]+.
Methyl 2-[N-(4-Chlorophenyl)benzamido]benzoate (3g)
Yield: 75.8 mg (83%); white solid; mp 135–137 °C.
HRMS (EI): m/z [M+] calcd for C21H17NO3: 331.1208; found:
331.1205.
IR (KBr): 1717, 1665, 1488, 1329, 1288, 1271, 1088, 714, 625
cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.91 (s, 1 H), 7.47 (d, J = 6.9 Hz,
3 H), 7.31 (dd, J = 15.9, 8.3 Hz, 2 H), 7.21 (dd, J = 18.0, 10.6 Hz, 4
H), 7.14–7.01 (m, 3 H), 3.80 (s, 3 H).
Methyl 2-(N-p-Tolylbenzamido)benzoate (3b)
Yield: 69.9 mg (81%); yellow oil.
IR (KBr): 1724, 1659, 1489, 1335, 1293, 1256, 1085, 757, 718, 623
cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.97 (s, 1 H), 7.47 (dd, J = 17.3,
8.0 Hz, 3 H), 7.23 (dt, J = 34.3, 7.4 Hz, 4 H), 7.15–6.75 (m, 5 H),
3.80 (s, 3 H), 2.27 (s, 3 H).
13C NMR (126 MHz, CDCl3): δ = 170.58, 166.44, 143.22, 141.30,
136.10, 136.00, 132.88, 131.05, 130.01, 129.57, 129.07, 128.75,
127.76, 127.48, 126.69, 126.00, 52.36, 20.97.
13C NMR (126 MHz, CDCl3): δ = 170.45, 166.18, 142.89, 135.51,
133.08, 131.80, 131.29, 130.37, 129.05, 128.83, 128.54, 127.95,
127.18, 52.44.
ESI-MS: m/z = 366.0 [M + H]+.
HRMS (EI): m/z [M+] calcd for C21H16ClNO3: 365.0819; found:
365.0833.
Methyl 2-[N-(4-Fluorophenyl)benzamido]benzoate (3h)
Yield: 75.9 mg (87%); pale yellow solid; mp 123–124 °C.
ESI-MS: m/z = 346.0 [M + H]+.
HRMS (EI): m/z [M+] calcd for C22H19NO3: 345.1365; found:
345.1361.
IR (KBr): 1724, 1659, 1506, 1449, 1334, 1277, 1082, 819, 718, 623
cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.95 (s, 1 H), 7.46 (d, J = 7.0 Hz,
3 H), 7.29 (t, J = 7.4 Hz, 2 H), 7.25–7.03 (m, 5 H), 6.92 (s, 2 H),
3.81 (s, 3 H).
Methyl 2-[N-(4-Methoxyphenyl)benzamido]benzoate (3c)
Yield: 83.9 mg (93%); white solid; mp 154–155 °C.
IR (KBr): 1720, 1659, 1507, 1343, 1247, 1083, 1028, 700, 624
cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.97 (s, 1 H), 7.47 (s, 3 H), 7.36–
7.15 (m, 5 H), 7.08 (d, J = 32.2 Hz, 2 H), 6.71 (s, 2 H), 3.82 (s, 3 H),
3.74 (s, 3 H).
13C NMR (126 MHz, CDCl3): δ = 170.59, 166.51, 157.82, 136.01,
132.85, 130.98, 129.94, 129.01, 127.78, 126.64, 114.19, 55.36,
52.38.
13C NMR (126 MHz, CDCl3): δ = 170.51, 166.32, 161.68, 159.72
(d, J = 245.0 Hz), 135.65, 133.00, 131.17, 130.22, 128.99, 128.78
(d, J = 26.3 Hz), 127.89, 127.02, 115.92, 115.74 (d, J = 22.5 Hz),
52.42.
ESI-MS: m/z = 350.0 [M + H]+.
HRMS (EI): m/z [M+] calcd for C21H16FNO3: 349.1114; found:
349.1125.
ESI-MS: m/z = 362.1 [M + H]+.
HRMS (EI): m/z [M+] calcd for C22H19NO4: 361.1314; found:
Methyl 2-[N-(2-Chlorophenyl)benzamido]benzoate (3i)
Yield: 33.8 mg (37%); mixture of two isomers (100:61); white
solid; mp 124–127 °C.
361.1319.
IR (KBr): 1722, 1667, 1598, 1476, 1331, 1259, 1087, 760, 710, 623
cm–1.
1H NMR (400 MHz, CDCl3): δ = 8.03 (d, J = 7.6 Hz, 1 H), 7.59 (d,
Methyl 2-(N-m-Tolylbenzamido)benzoate (3d)
Yield: 58.7 mg (68%); yellow oil.
IR (KBr): 1724, 1654, 1598, 1343, 1275, 1084, 756, 701, 632 cm–1.
J = 7.4 Hz, 2 H), 7.51–7.39 (m, 2 H), 7.38–7.00 (m, 8 H), 3.86 (s, 3
H).
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2013, 45, A–J

H
M.-G. Wang et al.
PAPER
13C NMR (126 MHz, CDCl3): δ = 171.06, 166.61, 142.10, 141.55,
141.29, 135.84, 133.02, 132.52, 131.17, 131.02, 130.57, 130.29,
129.32, 129.04, 128.77, 128.32, 128.19, 127.87, 127.73, 127.51,
126.70, 52.39.
ESI-MS: m/z = 410.2 [M + H]+.
HRMS (EI): m/z [M+] calcd for C21H16BrNO3: 409.0314; found:
409.0313.
ESI-MS: m/z = 366.2 [M + H]+.
HRMS (EI): m/z [M+] calcd for C21H16ClNO3: 365.0819; found:
Methyl 2-(2-Chloro-N-phenylbenzamido)benzoate (3n)
Yield: 70.4 mg (77%); mixture of two isomers (100:30); white
solid; mp 155–156 °C.
365.0810.
IR (KBr): 1725, 1662, 1592, 1492, 1437, 1262, 1089, 961, 770, 699,
621 cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.97 (dd, J = 7.8, 1.1 Hz, 1 H),
7.51 (td, J = 7.8, 1.2 Hz, 1 H), 7.39 (ddd, J = 25.1, 11.4, 4.3 Hz, 3
H), 7.32–7.18 (m, 4 H), 7.18–6.99 (m, 4 H), 3.94–3.80 (m, 3 H).
Methyl 2-(N-1-Naphthylbenzamido)benzoate (3j)
Yield: 57.2 mg (60%); mixture of two isomers (100:22); yellow oil.
IR (KBr): 1722, 1663, 1597, 1447, 1320, 1264, 1094, 775, 700
cm–1.
1H NMR (500 MHz, CDCl3): δ = 8.33 (s, 1 H), 8.00 (dd, J = 7.5, 1.4
Hz, 1 H), 7.87–7.74 (m, 1 H), 7.70 (t, J = 10.7 Hz, 1 H), 7.56–7.38
(m, 4 H), 7.38–7.16 (m, 5 H), 7.03 (t, J = 7.5 Hz, 2 H), 6.85 (d, J =
6.9 Hz, 1 H), 3.88 (s, 3 H).
13C NMR (126 MHz, CDCl3): δ = 172.26, 167.28, 142.41, 139.75,
136.47, 134.65, 132.56, 130.74, 130.17, 129.40, 128.27, 128.08,
127.81, 127.65, 127.33, 126.40, 126.13, 125.90, 125.64, 125.29,
123.78, 52.47.
13C NMR (126 MHz, CDCl3): δ = 167.51, 166.58, 142.78, 141.45,
136.20, 132.88, 131.61, 130.64, 129.96, 129.52, 129.13, 129.09,
128.95, 128.89, 127.61, 127.11, 127.09, 126.27, 52.46.
ESI-MS: m/z = 366.1 [M + H]+.
HRMS (EI): m/z [M+] calcd for C21H16ClNO3: 365.0819; found:
365.0822.
Methyl 2-(4-Nitro-N-phenylbenzamido)benzoate (3o)
Yield: 55.5 mg (59%); yellow oil.
IR (KBr): 1723, 1665, 1596, 1522, 1343, 1085, 734, 710 cm–1.
ESI-MS: m/z = 382.1 [M + H]+.
HRMS (EI): m/z [M+] calcd for C25H19NO3: 381.1365; found:
1H NMR (500 MHz, CDCl3): δ = 8.07 (d, J = 7.9 Hz, 3 H), 7.68 (d,
J = 6.7 Hz, 2 H), 7.51 (s, 1 H), 7.34 (d, J = 44.2 Hz, 2 H), 7.12 (t,
J = 36.1 Hz, 5 H), 3.86 (s, 3 H).
13C NMR (126 MHz, CDCl3): δ = 168.58, 166.21, 148.22, 142.95,
142.29, 133.30, 131.15, 129.95, 129.36, 128.89, 128.22, 127.85,
127.37, 127.15, 123.11, 52.49.
ESI-MS: m/z = 377.0 [M + H]+.
HRMS (EI): m/z [M+] calcd for C21H16N2O5: 376.1059; found:
381.1360.
Methyl 2-(4-Methyl-N-phenylbenzamido)benzoate (3k)
Yield: 64.7 mg (75%); yellow oil.
IR (KBr): 1724, 1660, 1491, 1339, 1293, 1257, 1084, 758, 605
cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.91 (s, 1 H), 7.44 (t, J = 7.4 Hz,
1 H), 7.38 (d, J = 7.9 Hz, 2 H), 7.29 (t, J = 7.4 Hz, 1 H), 7.22 (s, 2
H), 7.17–7.04 (m, 4 H), 7.00 (d, J = 8.0 Hz, 2 H), 3.78 (s, 3 H), 2.27
(s, 3 H).
376.1063.
13C NMR (126 MHz, CDCl3): δ = 170.63, 166.41, 144.01, 143.39,
140.45, 132.90, 131.10, 129.27, 128.88, 128.46, 127.44, 126.71,
126.08, 52.34, 21.42.
Methyl 2-[4-Bromo-N-(4-methoxyphenyl)benzamido]benzoate
(3p)
Yield: 85.8 mg (78%); yellow oil.
ESI-MS: m/z = 346.0 [M + H]+.
HRMS (EI): m/z [M+] calcd for C22H19NO3: 345.1365; found:
IR (KBr): 1724, 1654, 1588, 1508, 1343, 1247, 1084, 833, 746, 627
cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.98 (s, 1 H), 7.63–7.27 (m, 6 H),
345.1366.
7.20–6.96 (m, 3 H), 6.73 (s, 2 H), 3.82 (s, 3 H), 3.75 (s, 3 H).
Methyl 2-(3-Methyl-N-phenylbenzamido)benzoate (3l)
13C NMR (126 MHz, CDCl3): δ = 169.62, 166.43, 158.01, 142.92,
137.01, 136.57, 135.58, 135.00, 131.06, 130.71, 128.98, 128.83,
128.66, 126.78, 124.43, 114.36, 55.37, 52.40.
ESI-MS: m/z = 440.0 [M + H]+.
HRMS (EI): m/z [M+] calcd for C22H18BrNO4: 439.0419; found:
Yield: 58.7 mg (68%); pale yellow solid; mp 132–134 °C.
IR (KBr): 1713, 1651, 1590, 1382, 1350, 762, 738, 699 cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.92 (s, 1 H), 7.45 (t, J = 7.3 Hz,
1 H), 7.34 (s, 1 H), 7.31 (d, J = 6.9 Hz, 1 H), 7.20 (d, J = 7.3 Hz, 3
H), 7.17–7.01 (m, 6 H), 3.80 (s, 3 H), 2.24 (s, 3 H).
13C NMR (126 MHz, CDCl3): δ = 170.73, 166.42, 143.84, 143.19,
137.60, 135.76, 132.87, 131.07, 130.90, 129.80, 128.87, 127.52,
126.77, 126.19, 52.37, 21.25.
ESI-MS: m/z = 346.0 [M + H]+.
HRMS (EI): m/z [M+] calcd for C22H19NO3: 345.1365; found:
439.0422.
Methyl 2-[N-(4-Bromophenyl)-4-methylbenzamido]benzoate
(3q)
Yield: 72.1 mg (68%); yellow oil.
IR (KBr): 1724, 1662, 1486, 1327, 1293, 1070, 745, 607 cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.90 (s, 1 H), 7.45 (t, J = 7.4 Hz,
1 H), 7.41–7.26 (m, 5 H), 7.10 (d, J = 7.9 Hz, 1 H), 7.07–6.83 (m, 4
H), 3.77 (s, 3 H), 2.28 (s, 3 H).
13C NMR (126 MHz, CDCl3): δ = 170.44, 166.17, 143.04, 140.77,
137.94, 133.05, 132.49, 131.98, 131.28, 129.20, 128.83, 128.62,
127.05, 126.00, 119.52, 52.39, 21.45.
345.1361.
Methyl 2-(4-Bromo-N-phenylbenzamido)benzoate (3m)
Yield: 87.1 mg (85%); yellow oil.
IR (KBr): 1723, 1661, 1589, 1491, 1341, 1258, 1084, 758, 696
cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.97 (s, 1 H), 7.46 (d, J = 7.0 Hz,
1 H), 7.36 (dd, J = 15.7, 8.5 Hz, 5 H), 7.29–6.91 (m, 7 H), 3.80 (s,
3 H).
13C NMR (126 MHz, CDCl3): δ = 169.63, 166.27, 142.95, 137.04,
134.84, 133.09, 131.72, 131.55, 131.19, 131.08, 130.78, 129.09,
128.60, 127.62, 127.05, 126.50, 124.70, 52.41.
ESI-MS: m/z = 424.1 [M + H]+.
HRMS (EI): m/z [M+] calcd for C22H18BrNO3: 423.0470; found:
423.0475.
Methyl 2-(N-Methylbenzamido)benzoate (3r)
Yield: 47.1 mg (70%); yellow oil.
Synthesis 2013, 45, A–J
© Georg Thieme Verlag Stuttgart · New York

PAPER
N-Arylation of Secondary Acyclic Amides
I
IR (KBr): 1723, 1648, 1598, 1490, 1366, 1259, 1077, 701 cm–1.
13C NMR (126 MHz, CDCl3): δ = 170.47, 165.92, 143.77, 143.23,
135.97, 132.72, 130.95, 130.07, 129.35, 129.11, 128.83, 128.60,
127.75, 127.47, 126.85, 126.16, 65.21, 30.57, 19.13, 13.69.
1H NMR (500 MHz, CDCl3): δ = 7.78–7.72 (m, 1 H), 7.45 (t, J = 7.2
Hz, 1 H), 7.28–7.16 (m, 5 H), 7.11 (t, J = 7.5 Hz, 2 H), 3.87 (s, 3 H),
3.44 (s, 3 H).
ESI-MS: m/z = 374.1 [M + H]+.
13C NMR (126 MHz, CDCl3): δ = 170.51, 165.92, 144.83, 135.73,
133.08, 131.54, 129.82, 129.61, 128.36, 127.61, 127.27, 52.49,
38.33.
ESI-MS: m/z = 270.0 [M + H]+.
HRMS (EI): m/z [M+] calcd for C16H15NO3: 269.1052; found:
HRMS (EI): m/z [M+] calcd for C24H23NO3: 373.1678; found:
373.1680.
Methyl 4-Fluoro-2-(N-phenylbenzamido)benzoate (3w)
Yield: 46.3 mg (53%); yellow oil.
IR (KBr): 1725, 1664, 1593, 1495, 1334, 1259, 1109, 755, 700, 414
cm–1.
269.1056.
1H NMR (500 MHz, CDCl3): δ = 7.98 (d, J = 6.5 Hz, 1 H), 7.49 (d,
J = 7.5 Hz, 2 H), 7.32–7.20 (m, 5 H), 7.15 (dd, J = 17.4, 9.9 Hz, 3
H), 7.01 (t, J = 7.2 Hz, 1 H), 6.81 (d, J = 8.9 Hz, 1 H), 3.80 (s, 3 H).
13C NMR (126 MHz, CDCl3): δ = 170.60, 166.05, 165.51, 164.02
(d, J = 253.8 Hz), 143.42, 135.50, 133.32, 133.24 (d, J = 10.0 Hz),
130.39, 129.16, 127.88, 127.60, 126.66, 125.04, 116.81, 114.11,
113.94 (d, J = 21.3 Hz), 52.43.
Methyl 2-(N-p-Tolylacetamido)benzoate (3s)
Yield: 56.6 mg (80%); mixture of two isomers (100:40); yellow oil.
IR (KBr): 1726, 1674, 1509, 1488, 1291, 1086, 761, 589 cm–1.
1H NMR (500 MHz, CDCl3): δ = 8.00–7.82 (m, 1 H), 7.61–7.30 (m,
3 H), 7.28–7.22 (m, 1 H), 7.18 (t, J = 11.4 Hz, 1 H), 7.15–7.01 (m,
2 H), 3.92–3.82 (m, 3 H), 2.38–2.24 (m, 3 H), 2.02 (m, 3 H).
13C NMR (126 MHz, CDCl3): δ = 171.28, 166.77, 142.08, 141.06,
137.76, 132.69, 130.56, 130.23, 129.30, 128.63, 128.56, 128.06,
126.49, 125.80, 52.28, 23.21, 21.07.
ESI-MS: m/z = 350.0 [M + H]+.
HRMS (EI): m/z [M+] calcd for C21H16FNO3: 349.1114; found:
349.1112.
ESI-MS: m/z = 284.0 [M + H]+.
HRMS (EI): m/z [M+] calcd for C17H17NO3: 283.1208; found:
283.1205.
Acknowledgment
We gratefully thank the National Natural Science Foundation of
China (grant No. 31071720) for generous financial support.
Ethyl 2-(N-Phenylbenzamido)benzoate (3t)
Yield: 69.1 mg (80%); white solid; mp 90–92 °C.
IR (KBr): 2987, 1719, 1655, 1598, 1490, 1346, 1258, 1080, 757,
701, 625 cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.90 (s, 1 H), 7.49 (d, J = 7.6 Hz,
2 H), 7.43 (t, J = 7.0 Hz, 1 H), 7.35–7.24 (m, 3 H), 7.19 (t, J = 7.6
Hz, 4 H), 7.12 (d, J = 7.6 Hz, 3 H), 4.26 (d, J = 6.3 Hz, 2 H), 1.27
(t, J = 7.0 Hz, 3 H).
13C NMR (126 MHz, CDCl3): δ = 170.49, 165.96, 143.82, 143.17,
135.98, 132.77, 131.00, 130.11, 129.35, 129.12, 128.90, 127.79,
127.53, 126.87, 126.22, 61.39, 14.20.
Supporting Information for this article is available online at
http://www.thieme-connect.com/ejournals/toc/synthesis.SnoIufproi
m
tgioSrantnugIifoop
r
itmnatr
Primary Data for this article are available online at
http://www.thieme-connect.com/ejournals/toc/synthesis and can be
cited using the following DOI: 10.4125/pd0047thmPirDayrmaPtiPrDi
m
rayhp421y.rD05/ta
d
?.aZteanh1l01
C
hemrysti
ESI-MS: m/z = 346.0 [M + H]+.
HRMS (EI): m/z [M+] calcd for C22H19NO3: 345.1365; found:
345.1364.
References
(1) (a) Wagner, J.; Wagner, M. L.; Hening, W. A. Ann.
Pharmacother. 1998, 36, 680. (b) VanBever, W. F. M.;
Niemegeers, C. J. E.; Janssen, P. A. J. J. Med. Chem. 1974,
17, 1047. (c) Anderson, R.; Hokama, T.; Lee, S.-F.; Oey, R.;
Elich, T.; Breazeale, S. US Patent 0200461, 2008; Chem.
Abstr. 2008, 149, 261123.
(2) Ullmann, F. Chem. Ber. 1903, 36, 2382.
(3) Goldberg, I. Chem. Ber. 1906, 39, 1691.
(4) (a) Antilla, J. C.; Klapars, A.; Buchwald, S. L. J. Am. Chem.
Soc. 2002, 124, 11684. (b) Buchwald, S. L.; Klapars, A.;
Huang, X. H. J. Am. Chem. Soc. 2002, 124, 7421.
(c) Cristau, H. J.; Cellier, P.; Spindler, J. F.; Taillefer, M.
Eur. J. Org. Chem. 2004, 695.
Cyclohexyl 2-(N-Phenylbenzamido)benzoate (3u)
Yield: 77.8 mg (78%); yellow oil.
IR (KBr): 2936, 2857, 1716, 1663, 1596, 1491, 1339, 1255, 1082,
757, 696, 625 cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.87 (d, J = 7.0 Hz, 1 H), 7.50 (d,
J = 7.4 Hz, 2 H), 7.42 (t, J = 7.3 Hz, 1 H), 7.34–7.07 (m, 10 H), 4.89
(s, 1 H), 1.86 (s, 2 H), 1.69 (s, 2 H), 1.50 (dd, J = 26.0, 17.4 Hz, 2
H), 1.39–1.30 (m, 2 H), 1.25 (dd, J = 14.1, 8.4 Hz, 2 H).
13C NMR (126 MHz, CDCl3): δ = 170.34, 165.27, 143.79, 143.17,
136.09, 132.52, 130.88, 129.96, 129.90, 129.11, 128.78, 127.72,
126.85, 126.08, 73.76, 31.49, 26.92, 25.37, 23.74.
(5) Cai, Q.; Zhu, W.; Zhang, H.; Zhang, Y. D.; Ma, D. W.
Synthesis 2005, 496.
(6) (a) Guo, X.; Rao, H.; Fu, H.; Jiang, Y.; Zhao, Y. Adv. Synth.
Catal. 2006, 348, 2197. (b) Zhang, H.; Cai, Q.; Ma, D. W.
J. Org. Chem. 2005, 70, 5164. (c) Ma, D.; Cai, Q.; Zhang, H.
Org. Lett. 2003, 5, 2453.
(7) Lv, X.; Bao, W. J. Org. Chem. 2007, 72, 3863.
(8) Kwong, F. Y.; Klapars, A.; Buchwald, S. L. Org. Lett. 2002,
4, 581.
ESI-MS: m/z = 400.3 [M + H]+.
HRMS (EI): m/z [M+] calcd for C26H25NO3: 399.1834; found:
399.1831.
Butyl 2-(N-Phenylbenzamido)benzoate (3v)
Yield: 77.4 mg (83%); yellow oil.
IR (KBr): 2959, 2872, 1720, 1663, 1597, 1491, 1339, 1255, 1082,
757, 696, 624 cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.87 (d, J = 7.4 Hz, 1 H), 7.57–
7.40 (m, 3 H), 7.35–7.03 (m, 10 H), 4.20 (s, 2 H), 1.72–1.56 (m, 2
H), 1.37 (d, J = 6.7 Hz, 2 H), 0.90 (t, J = 7.4 Hz, 3 H).
(9) Racine, E.; Monnier, F.; Vors, J.-P.; Taillefer, M. Org. Lett.
2011, 13, 2818.
(10) For representative references on the use of xantphos or
XPhos, see: (a) Yin, J.; Buchwald, S. L. Org. Lett. 2000, 2,
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2013, 45, A–J

J
M.-G. Wang et al.
PAPER
Molecules 2010, 15, 1154. (i) Maiti, D.; Buchwald, S. L.
1101. (b) Yin, J.; Buchwald, S. L. J. Am. Chem. Soc. 2002,
124, 6043. (c) Shen, Q.; Hartwig, J. F. J. Am. Chem. Soc.
2007, 129, 7734. (d) Huang, J.; Chen, Y.; King, A. O.;
Dilmeghani, M.; Larsen, R. D.; Faul, M. M. Org. Lett. 2008,
10, 2609. (e) Manley, P. J.; Bilodeau, M. T. Org. Lett. 2004,
6, 2433. (f) Audisio, D.; Messaoudi, S.; Peyrat, J.-F.; Brion,
J.-D.; Alami, M. Tetrahedron Lett. 2007, 48, 6928.
(g) Messaoudi, S.; Audisio, D.; Brion, J.-D.; Alami, M.
Tetrahedron 2007, 63, 10202. (h) Artamkina, G. A.;
Sergeev, A. G.; Beletskaya, I. P. Tetrahedron Lett. 2001, 42,
4381.
J. Org. Chem. 2010, 75, 1791.
(13) (a) Wang, M.-G.; Wu, J.; Shang, Z.-C. Synlett 2012, 23, 589.
(b) Wang, M.; Yu, H.; You, X.; Wu, J.; Shang, Z. Chin. J.
Chem. 2012, 30, 2356.
(14) See the Supporting Information for details.
(15) (a) Monnier, F.; Taillefer, M. Angew. Chem. Int. Ed. 2009,
48, 6954. (b) Ley, S. V.; Thomas, A. W. Angew. Chem. Int.
Ed. 2003, 42, 5400. (c) Frlan, R.; Kikelj, D. Synthesis 2006,
2271. (d) Evano, G.; Blanchard, N.; Toumi, M. Chem. Rev.
2008, 108, 3054. (e) Kunz, K.; Scholz, U.; Ganzer, D.
Synlett 2003, 2428.
(16) (a) Phipps, R. J.; Gaunt, M. J. Science 2009, 323, 1593.
(b) Phipps, R. J.; Grimster, N. P.; Gaunt, M. J. J. Am. Chem.
Soc. 2008, 130, 8172. (c) Ribas, X.; Jackson, D. A.;
Donnadieu, B.; Mahía, J.; Parella, T.; Xifra, R.; Hedman, B.;
Hodgson, K. O.; Llobet, A.; Stack, T. D. P. Angew. Chem.
Int. Ed. 2002, 41, 2991. (d) Casitas, A.; King, A. E.; Parella,
T.; Costas, M.; Stahl, S. S.; Ribas, X. Chem. Sci. 2010, 1,
326. (e) Cai, Q.; Zou, B.; Ma, D. Angew. Chem. Int. Ed.
2006, 45, 1276. (f) Strieter, E. R.; Bhayana, B.; Buchwald,
S. L. J. Am. Chem. Soc. 2009, 131, 78. (g) Ouali, A.;
Spindler, J.-F.; Jutand, A.; Taillefer, M. Adv. Synth. Catal.
2007, 349, 1906. (h) Zhang, S.-L.; Liu, L.; Fu, Y.; Guo,
Q.-X. Organometallics 2007, 26, 4546.
(11) Hick, J. D.; Hyde, A. M.; Martinez Cuezva, A.; Buchwald,
S. L. J. Am. Chem. Soc. 2009, 131, 16720.
(12) (a) Chen, W.; Li, J.; Fang, D.; Feng, C.; Zhang, C. Org. Lett.
2008, 10, 4565. (b) Klapars, A.; Antilla, J. C.; Huang, X.;
Buchwald, S. L. J. Am. Chem. Soc. 2001, 123, 7727.
(c) Klapars, A.; Antilla, J. C.; Huang, X.; Buchwald, S. L.
J. Am. Chem. Soc. 2002, 124, 7421. (d) Lange, J. H. M.;
Hofmeyer, L. J. F.; Hout, F. A. S.; Osnaburg, S. J. M.;
Verveer, P. C.; Kruse, C. G.; Feenstra, R. W. Tetrahedron
Lett. 2002, 43, 1101. (e) Deng, W.; Wang, Y. F.; Zou, Y.;
Liu, L.; Guo, Q. X. Tetrahedron Lett. 2004, 45, 2311.
(f) Ikawa, T.; Barder, T. E.; Biscoe, M. R.; Buchwald, S. L.
J. Am. Chem. Soc. 2007, 129, 13001. (g) Mino, T.; Harada,
Y.; Shindo, H.; Sakamoto, M.; Fujita, T. Synlett 2008, 614.
(h) Wang, C.; Liu, L.; Wang, W.; Ma, D.-S.; Zhang, H.
(17) Yoshida, H.; Shirakawa, E.; Honda, Y.; Hiyama, T. Angew.
Chem. Int. Ed. 2002, 41, 3247.
Synthesis 2013, 45, A–J
© Georg Thieme Verlag Stuttgart · New York