One-pot synthesis of ferrocenyl ketones containing biaryls and 6-aryl-2-ferrocenylquinolines via Ir/pd-cocatalyzed α-alkylation/suzuki reaction

Article abstract of DOI:10.1021/jo401421b

An efficient PPh₃-cyclometalated iridium(III) benzo[h]quinoline hydride 1/Pd(OAc)₂-cocatalyzed three-component α-alkylation/ Suzuki reaction has been developed. The three-component reaction of 4-bromobenzyl alcohol, acetylferrocene, and arylboronic acids gives ferrocenyl ketones containing biaryls in moderate to good yields. This method was successfully applied to a one-pot synthesis of 6-aryl-2-ferrocenyl quinolines, using (2-amino-5-bromophenyl)methanol instead of 4-bromobenzyl alcohol.

Full text of DOI:10.1021/jo401421b

Article
pubs.acs.org/joc
One-Pot Synthesis of Ferrocenyl Ketones Containing Biaryls and
6‑Aryl-2-ferrocenylquinolines via Ir/Pd-Cocatalyzed α‑Alkylation/
Suzuki Reaction
Chen Xu,*,†,‡ Xin-Qi Hao,‡ Zhi-Qiang Xiao,‡ Zhi-Qiang Wang,† Xiao-Er Yuan,‡ Wei-Jun Fu,†
Bao-Ming Ji,† and Mao-Ping Song*,‡
†College of Chemistry, Chemical Engineering, Luoyang Normal University, Luoyang, Henan 471022, China
‡College of Chemistry, Molecular Engineering, Zhengzhou University, Zhengzhou, Henan 450052, China
S
* Supporting Information
ABSTRACT: An efficient PPh3-cyclometalated iridium(III) benzo[h]quinoline hydride 1/Pd(OAc)2-cocatalyzed three-
component α-alkylation/Suzuki reaction has been developed. The three-component reaction of 4-bromobenzyl alcohol,
acetylferrocene, and arylboronic acids gives ferrocenyl ketones containing biaryls in moderate to good yields. This method was
successfully applied to a one-pot synthesis of 6-aryl-2-ferrocenyl quinolines, using (2-amino-5-bromophenyl)methanol instead of
4-bromobenzyl alcohol.
improve both the atom efficiency and the regioselectivity of the
process, producing only water as a side product. To our
knowledge, there are no reports concerning a three-component
reaction that consists of α-alkylation and Suzuki reaction
catalyzed by two metals based on a same ligand.
INTRODUCTION
■
The multicomponent reactions (MCRs) are one-pot processes
that offer significant advantages over classical step-by-step
approaches, allowing the formation of several bonds and
construction of complex molecules from readily available
starting materials in a single synthetic operation.1 For the
design of a MCR, it is important to study the catalyst
compatibility with materials from the catalytic steps comprising
the overall process. In most cases, two (or more) different
metals/ligands were added to the reaction medium to afford the
two (or more) transformations.2 Because there are many
different reactions that can be catalyzed by the same ligand, it is
possible for the catalyst (two different metals based on a same
ligand) to initiate two or more mechanistically distinct reactions
in a MCR. This alternative is highly desirable in view of
economic and practical points. Transition-metal-catalyzed
reactions such as α-alkylation and Suzuki reaction have become
an extremely powerful method in organic synthesis for the
formation of carbon−carbon bonds.3 In these reactions, halides
are the most commonly used electrophiles. Recently, there has
been significant interest in the transition-metal-catalyzed
hydrogen autotransfer process by alcohols as a more benign
alternative to potentially genotoxic halides.4 This strategy can
Several groups have reported the use of Ru,5 Pd,6 and Ni7
catalysts for the α-alkylation of ketones with alcohols. In
addition, Ir complexes serve as efficient catalysts for hydrogen
transfer from alcohols to aldehydes,8 and they have been
utilized in α-alkylation of ketones. Among them, [Ir(cod)Cl]2
has been the most commonly employed Ir catalyst for this
reaction.9 Ishii and co-workers reported direct α-alkylation of
ketones and acetates with primary alcohols catalyzed by an
[Ir(cod)Cl]2/PPh3/base system.10 We have also found that
PPh3-cyclometalated iridium(III) pyrimidine complexes were
very efficient catalysts for α-alkylation.11 Considering that PPh3
is the most common ligand in the Suzuki reaction,12 we
speculate that Pd(OAc)2 in combination with PPh3-cyclo-
metalated iridium(III) complex can cocatalyze α-alkylation and
Suzuki reaction. Since the discovery of ferrocene in 1951,13 the
Received: July 5, 2013
© XXXX American Chemical Society
A
dx.doi.org/10.1021/jo401421b | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
preparation of functionalized ferrocenyl derivatives has been
extensively studied, especially with respect to applications in
organic synthesis, materials chemistry, and biochemistry.14 As a
continuation of our interest in the synthesis and application of
ferrocenyl derivatives,15 we prepared a new PPh3-cyclo-
metalated iridium(III) benzo[h]quinoline hydride 1 and
described the first Ir/Pd-cocatalyzed one-pot reaction of
bromoarylmethanols, acetylferrocene, and arylboronic acids,
providing a series of ferrocenyl ketones containing biaryls and
6-aryl-2-ferrocenylquinolines.
characterized by elemental analysis, IR, NMR, and also by X-ray
diffraction analysis. The IR spectrum of 1 show νIr−H at 2133
1
cm−1, and the H NMR spectrum reveals a triplet of hydride
resonances at −16.86 ppm (t, JP−H = 16.3 Hz). The crystal
structure of 1 shows the H being trans to the nitrogen of
benzo[h]quinoline (Figure S1 in Supporting Information). The
Ir−C, Ir−Cl, and Ir−H bond lengths of 1 are similar to those of
related cyclometalated iridium(III) hydrides.16
In 2006, Yus and co-workers reported direct α-alkylation of
acetylferrocene with phenylmethanol catalyzed by
RuCl2(DMSO)4, while the reaction gave the expected product
only in a very low yield (17%).5c We have previously shown
that PPh3-cyclometalated iridium(III) complexes effectively
catalyzed the above reaction, giving 83% yield.11 On the basis of
the success of this approach, we were interested to see whether
the obtained PPh3-cyclometalated iridium(III) hydride 1 would
be an efficient catalyst for α-alkylation of acetylferrocene with
arylmethanols. Fortunately, the α-alkylations of acetylferrocene
with a variety of arylmethanols were carried out with catalytic
loadings of 2 mol % (relative to acetylferrocene) in the
presence of KOH as base in dioxane at 110 °C, affording the
products in excellent yields (Table 1). Furthermore, the
coupling of hindered arylmethanols with acetylferrocene also
gave the desired products 6 and 7 in good yields (92 and 88%,
respectively).
RESULTS AND DISCUSSION
The preparation of new PPh3-cyclometalated iridium(III)
hydride 1 is as follows (Scheme 1): A reaction mixture of
■
Scheme 1. Preparation of PPh3-Cyclometalated Iridium(III)
Hydride 1
Since it is known that simple catalyst Pd(OAc)2/PPh3 can
catalyze organic halides and arylboronic acids to form a variety
of biaryls,12 we hypothesized that Pd(OAc)2 in combination
with PPh3-cyclometalated iridium(III) hydride can cocatalyze
one-pot α-alkylation/Suzuki reaction. The three-component
reaction of acetylferrocene, 4-bromobenzyl alcohol, and
phenylboronic acid was carried out with various bases and
solvents in the presence of Ir/Pd catalysts. The results from this
[Ir(cod)Cl]2, PPh3, and benzo[h]quinoline in 2-ethoxyethanol
was refluxed under N2 for 12 h and then cooled to room
temperature. The yellow precipitate was filtered and washed
with ethanol several times, and the crude product was
recrystallized from CH2Cl2, giving yellow crystals of 1. It was
a
Table 1. α-Alkylation of Acetylferrocene with Arylmethanols Catalyzed by 1
a
Reaction conditions: acetylferrocene (0.5 mmol), arylmethanols (0.6 mmol), 1 (2 mol %), KOH (0.5 mmol), dioxane (3 mL), 110 °C, 12 h,
b
nitrogen atmosphere. Yield (average of two runs).
B
dx.doi.org/10.1021/jo401421b | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
a
Table 2. Optimization of the Three-Component Reaction Conditions
b
entry
catalyst (mol %)
1/Pd(OAc)2 (2/3)
base (equiv)
KOH (3)
solvent
yield (%)
1
2
3
4
5
6
dioxane
dioxane
dioxane
dioxane
toluene
THF
38
1/Pd(OAc)2 (2/3)
1/Pd(OAc)2 (2/3)
1/Pd(OAc)2 (2/3)
1/Pd(OAc)2 (2/3)
1/Pd(OAc)2 (2/3)
1 (2)
K2CO3 (3)
30
Cs2CO3 (3)
43
KOH/Cs2CO3 (1/2)
KOH/Cs2CO3 (1/2)
KOH/Cs2CO3 (1/2)
KOH/Cs2CO3 (1/2)
KOH/Cs2CO3 (1/2)
KOH/Cs2CO3 (1/2)
KOH/Cs2CO3 (1/2)
KOH/Cs2CO3 (1/2)
KOH/Cs2CO3 (1/2)
87
57
14
c
7
dioxane
dioxane
dioxane
dioxane
dioxane
dioxane
trace
trace
76
d
8
Pd(OAc)2/PPh3 (3/6)
1/PdCl2 (2/3)
9
10
11
12
1/Pd(dba)2 (2/3)
[Ir(cod)Cl]2/PPh3/Pd(OAc)2 (1/4/3)
IrCl3/Pd(OAc)2 (2/3)
85
40
trace
a
Reaction conditions: acetylferrocene (0.5 mmol), 4-bromobenzyl alcohol (0.6 mmol), phenylboronic acid (0.75 mmol), solvent (3 mL), 110 °C, 18
b
c
d
h, nitrogen atmosphere. Yield (average of two runs). Main product is 4 (98%). Main product is biphenyl-4-methanol (38%).
a
Table 3. One-Pot Synthesis of Ferrocenyl Ketones Containing Biaryls
a
Reaction conditions: acetylferrocene (0.5 mmol), 4-bromobenzyl alcohol (0.6 mmol), arylboronic acids (0.75 mmol), 1/Pd(OAc)2 (2−3 mol %),
b
KOH/Cs2CO3 (0.5 mmol/1 mmol), dioxane (3 mL), 110 °C, 18 h, nitrogen atmosphere. Yield (average of two runs).
study are summarized in Table 2. It was disappointing to find at
the beginning that the isolated yields of the product 8 were
only 30−43% with 2−3 mol % of 1/Pd(OAc)2 in dioxane using
single base (KOH, K2CO3, and Cs2CO3). However, when the
dual bases KOH/Cs2CO3 were used, the yield increased to 87%
(entry 4). Among the tested solvents, dioxane was much better
than other solvents such as toluene and THF (entries 5 and 6).
Only complex 1 is used as catalyst for the above reaction (entry
7); the expected product 8 was not isolated, and the main
product was α-alkyl product 4 (98%). Using Pd(OAc)2/PPh3 as
C
dx.doi.org/10.1021/jo401421b | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
catalyst in the absence of the Ir complex 1 provided the main
product (38%) biphenyl-4-methanol15d (entry 8). In addition,
the activities of several related catalytic systems in the same
model reaction were investigated. 1/PdCl2 and 1/Pd(dba)2 also
showed comparable activity, producing the product in 76−85%
yields (entries 9 and 10). [Ir(cod)Cl]2/PPh3/Pd(OAc)2
generated the product in low yield (40%, entry 11). However,
IrCl3/Pd(OAc)2 was almost inactive under the same reaction
conditions (entry 12), suggesting that PPh3 participated in the
catalytic cycles.
To test this procedure, the scope of the reaction was then
investigated with various arylboronic acids under the
established protocol (Table 3). Similar to the result of
phenylboronic acid, good yields (84−86%) were also obtained
in the cases of 1-naphthylboronic acid and 4-biphenylboronic
acid. For electron-rich arylboronic acids, they could provide the
corresponding products 11−13 in good to excellent yields
(85−90%). In cases of electron-deficient arylboronic acids
containing −CO−, −COOCH3, or −NO2 groups, an obvious
decrease in yield was observed (63−78%). This three-
component coupling was found also to proceed successfully
with heteroarylboronic acid, such as pyridin-3-ylboronic acid,
furnishing 17 in a moderate yield (56%).
(dihedral angles of 84.7 and 95.8° for 9 and 13, respectively).
The most striking common features are intramolecular
(unsubstituted Cp) C−H···π (the middle benzene ring)
interactions17 of 2.653 and 2.608 Å for 9 and 13, respectively.
Quinolines and their derivatives are well-known as important
natural products which are often endowed with many
pharmacological properties.18 In spite of the existence of
many synthetic routes, there are limited reports involving
ferrocenylquinolines.5c,19 Among them, the metal-catalyzed
modified Friedlaender reaction20 is one of the simplest
methods, where 2-aminobenzyl alcohol, which is cheaper and
more stable than 2-aminobenzaldehyde, is allowed to react with
carbonyl compounds via hydrogen transfer reaction and
cyclization to form quinoline derivatives.5c,21 To date, only
one account has been reported concerning the synthesis of
quinolines from amino alcohols and ketones catalyzed by Ir
catalysts.21d However, this reaction has not involved ferrocenyl-
quinolines. Thus, the development of efficient methodologies
for the synthesis of substituted ferrocenylquinolines from
simple, readily available starting materials is still desired.
Prompted by the good results obtained in the synthesis of
ferrocenyl ketones containing biaryls, we explored whether this
strategy would allow the preparation of substituted ferrocenyl-
quinolines. The direct three-component reaction of acetylfer-
rocene, (2-amino-5-bromophenyl)methanol, and phenylbor-
onic acid was selected as the model reaction. Disappointingly,
the expected three-component coupled product 19 was not
isolated; the main product was α-alkyl product 2-ferrocenyl-6-
bromoquinoline 18 (78%), clearly showing that Suzuki reaction
did not proceed. Thus, we carried out the 1-catalyzed α-
alkylation of acetylferrocene and (2-amino-5-bromophenyl)-
methanol, let it reach completion (98% yield), and then added
the Pd(OAc)2, Cs2CO3, and phenylboronic acid dissolved in
the same solvent, and the reaction was continued. To our
delight, 6-phenyl-2-ferrocenylquinoline 19 could be synthesized
in high yield (91%) by a one-pot, two-step procedure (Scheme
2). This protocol was equally efficient compared to the
combined individual reactions but without any workup or
isolation of the intermediate.
The exact structures of products 9 and 13 were further
determined by single-crystal X-ray crystallography and shown
in Figure 1 and Figure S2 (see Supporting Information). The
The scope of the procedure was further investigated by
varying the arylboronic acids (Table 4). Good yields were
obtained for the coupling of naphthylboronic acids or 4-
biphenylboronic acid to give 20, 21, and 22 in 90, 88, and 87%
yields, respectively. The electronic nature of the substituents on
the arylboronic acids did have an effect on the reaction.
Electron-donating substrates reacted to give the correponding
products 23 and 24, and the yields (92 and 93%) are slightly
higher than the yields of electron-withdrawing substrates.
Reaction with para-, ortho-, and meta-arylboronic acids
proceeded efficiently to form the expected products 23 and
34 in moderate to good yields (43−93%). A slight decrease in
the yields of meta-substitution products 28−30 was observed.
Figure 1. Molecular structure of compound 9. Non-hydrogen bonding
H atoms are omitted for clarity.
crystal structures of the two compounds are similar; the middle
benzene ring plane is almost perpendicular to the Cp ring
Scheme 2. Synthesis of 6-Aryl-2-ferrocenylquinoline 19
D
dx.doi.org/10.1021/jo401421b | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
a
Table 4. One-Pot Synthesis of 6-Aryl-2-ferrocenylquinolines
a
Reaction conditions: acetylferrocene (0.5 mmol), (2-amino-5-bromophenyl)methanol (0.6 mmol), arylboronic acids (0.75 mmol), 1/Pd(OAc)2
b
(2−3 mol %), KOH/Cs2CO3 (0.5 mmol/1 mmol), dioxane (3 mL), 110 °C, nitrogen atmosphere. Yield (average of two runs).
In the same manner, switching the methyl or methoxy group
from the para-position to the ortho-position on the benzene
ring does obviously influence the yields of 32 and 33 (68 and
71%), demonstrating that steric factors have an influence on the
Suzuki reaction. The very sterically hindered 2,6-dimethyl-
phenylboronic acid only provided the corresponding product
34 in a 43% yield.
Finally, we examined the one-pot three-component reactions
of heteroarylboronic acids. Compared with the yield of 17
(56%), the yield (84%) of 35 starting from the same pyridin-3-
E
dx.doi.org/10.1021/jo401421b | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
3-(4-Bromophenyl)-1-ferrocenylpropan-1-one (4): Yield 190.6
mg, 96%; IR (KBr, cm−1) 2927, 1666, 1584, 1486, 1455, 1408, 1377,
1254, 1105, 1071, 1010, 876, 814; 1H NMR (400 MHz, CDCl3) δ 7.42
(d, J = 8.4 Hz, 2H), 7.16 (d, J = 8.4 Hz, 2H), 4.75 (s, 2H), 4.48 (s,
2H), 4.09 (s, 5H), 2.99 (s, 3H); 13C NMR (100 MHz, CDCl3) δ
202.7, 140.6, 131.5, 130.4, 119.8, 78.8, 72.3, 69.7, 69.2, 41.1, 29.4; MS
(EI, 70 eV) m/z = 397.0 (M + H)+. Anal. Calcd (%) for
C19H17BrFeO: C, 57.47; H, 4.32. Found: C, 57.59; H, 4.23.
ylboronic acid increased obviously. The method proved to be
effective for pyridinylboronic acids bearing a variety of
functional groups, including esters (37 and 38), ethers (39),
and amines (40). The detailed structures of 23, 29, 32, and 40
were confirmed by single-crystal X-ray crystallography (Figure
S3 in Supporting Information). In each compound, the
substituent Cp ring and the quinoline ring are approximately
coplanar.
In conclusion, we have developed a PPh3-cyclometalated
iridium(III) hydride/Pd(OAc)2-cocatalyzed three-component
reaction of acetylferrocene, bromoarylmethanols, and arylbor-
onic acids. This one-pot protocol provides efficient access to a
variety of ferrocenyl ketones containing biaryls and 6-aryl-2-
ferrocenylquinolines via α-alkylation and Suzuki reaction. The
advantages of this method include simple operation, high
efficiency, good functional tolerance, diversity of the starting
material, and that an additional ligand is not required.
1-Ferrocenyl-3-(2-methylphenyl)propan-1-one (6): Yield
198.2 mg, 92%; IR (KBr, cm−1) 2926, 1663, 1571, 1491, 1454,
1
1403, 1378, 1253, 1104, 1002, 879, 831, 761; H NMR (400 MHz,
CDCl3) δ 7.24 (d, J = 6.4 Hz, 1H), 7.13−7.18 (m, 3H), 4.77 (s, 2H),
4.48 (s, 2H), 4.11 (s, 5H), 3.03 (t, J = 6.8 Hz, 2H), 2.98 (t, J = 6.8 Hz,
2H), 2.39 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 203.4, 139.8,
136.0, 130.5, 129.1, 126.5, 126.3, 79.1, 72.4, 69.8, 69.4, 40.2, 27.7, 19.5;
MS (EI, 70 eV) m/z = 333.1 (M + H)+. Anal. Calcd (%) for
C20H20FeO: C, 72.31; H, 6.07. Found: C, 72.45; H, 5.96.
3-(2-Bromophenyl)-1-ferrocenylpropan-1-one (7): Yield 174.8
mg, 88%; IR (KBr, cm−1) 2923, 1667, 1565, 1469, 1451, 1377, 1293,
1227, 1107, 1083, 1020, 815, 758, 745; 1H NMR (400 MHz, CDCl3) δ
7.56 (d, J = 8.0 Hz, 1H), 7.39 (d, J = 7.4 Hz, 1H), 7.26 (t, J = 8.0 Hz,
1H), 7.09 (t, J = 7.6 Hz, 1H), 4.79 (s, 2H), 4.49 (s, 2H), 4.10 (s, 5H),
3.17 (t, J = 7.0 Hz, 2H), 3.06 (t, J = 7.0 Hz, 2H); 13C NMR (100
MHz, CDCl3) δ 203.0, 140.9, 133.1, 131.5, 128.2, 127.8, 124.4, 79.0,
72.4, 69.9, 69.4, 39.6, 31.0; MS (EI, 70 eV) m/z = 397.0 (M + H)+.
Anal. Calcd (%) for C19H17BrFeO: C, 57.47; H, 4.32. Found: C, 57.36;
H, 4.41.
General Procedure for Synthesis of Ferrocenyl Ketones
Containing Biaryls. The reaction of the acetylferrocene (0.5 mmol),
4-bromobenzyl alcohol (0.6 mmol), arylboronic acids (0.75 mmol),
KOH (0.5 mmol), and Cs2CO3 (1.0 mmol) at 110 °C for 18 h in
dioxane (3 mL) in the presence of 1/Pd(OAc)2 (0.01 mmol/0.015
mmol) under nitrogen affords the red products 8−17 after evaporation
of the solvent and purification on silica gel using dichloromethane as
eluent.
EXPERIMENTAL SECTION
■
General Information. The IR spectra were recorded on an FT-IR
spectrometer on KBr pellets. 1H and 13C NMR spectra were recorded
on a spectrometer in CDCl3 at 400 and 100 MHz, respectively, with
TMS as internal standard. MS experiments were performed with EI
source. All new compounds were further characterized by elemental
analysis. All reactions were carried out under a dry nitrogen
atmosphere using standard Schlenk techniques. Solvents were dried
and freshly distilled prior to use. All other chemicals were
commercially available except for (2-amino-5-bromophenyl)methanol,
which was prepared according to the published procedures.22
Compounds 3,23 5,23 and 1819e are known compounds, and other
compounds are new compounds.
Preparation of Compound 1. A reaction mixture of [Ir(cod)Cl]2
(0.5 mmol), benzo[h]quinoline (1.2 mmol), and PPh3 (2.2 mmol) in
2-ethoxyethanol (15 mL) was refluxed under an nitrogen atmosphere
for 10 h and then cooled to room temperature. A yellow precipitate
was filtered and washed with water and ethanol several times,
recrystallized in CH2Cl2, and dried under vacuum as a yellow solid
(838.4 mg, 90%): IR (KBr, cm−1) 3049, 2133, 1568, 1482, 1432, 1403,
1330, 1188, 1090, 836, 742, 722; 1H NMR (400 MHz, CDCl3) δ 9.10
(d, J = 6.4 Hz, 1H), 7.73 (d, J = 7.8 Hz, 1H), 7.66 (t, J = 8.0 Hz, 1H),
7.45−7.52 (m, 3H), 7.21−7.27 (m, 11H), 6.95−7.10 (m, 19H), 6.65
(d, J = 7.3 Hz, 1H), 6.44 (t, J = 8.4 Hz, 1H), −16.86 (t, J = 16.3 Hz,
1H); 13C NMR (100 MHz, CDCl3) δ 155.1, 148.4, 140.4, 134.1,
133.8, 131.7, 131.4, 129.5, 128.8, 127.1, 127.0, 125.7, 122.6, 119.8,
117.6; MS (EI, 70 eV) m/z = 896.2 (M − Cl)+. Anal. Calcd (%) for
C49H39ClIrNP2: C, 63.18; H, 4.22; N, 1.50. Found: C, 63.41; H, 4.03;
N, 1.67.
General Procedure for α-Alkylation of Acetylferrocene with
Arylmethanols. To a solution of Ir(III) complex 1 (0.01 mmol) in
solution (3 mL) were added acetylferrocene (0.5 mmol), the
corresponding alcohol (0.6 mmol), and base (0.5 mmol) under
nitrogen. The reaction mixture was then placed in an oil bath and
heated at 110 °C for 12 h, cooled, and quenched with water. The
organic layer was separated, and the aqueous layer was extracted with
ethyl acetate, then the combined organic layers were washed with
water, dried over MgSO4, filtered, and the solvent was removed on a
rotary evaporator. The resulting residue was purified by flash
chromatography on silica gel using CH2Cl2 as eluent. The second
band was collected and afforded the red solids 2−7.
3-Biphenyl-1-ferrocenylpropan-1-one (8): Yield 171.5 mg,
87%; IR (KBr, cm−1) 2922, 1663, 1484, 1453, 1405, 1377, 1253,
1
1105, 1077, 1026, 1009, 877, 816, 762, 696; H NMR (400 MHz,
CDCl3) δ 7.56 (t, J = 8.0 Hz, 4H), 7.30−7.43(m, 5H), 4.78 (s, 2H),
4.48 (s, 2H), 4.09 (s, 5H), 3.07 (s, 4H); 13C NMR (100 MHz, CDCl3)
δ 203.3, 141.2, 140.9, 139.3, 129.2, 128.9, 127.4, 127.2, 127.1, 79.1,
72.4, 69.8, 69.4, 41.6, 29.9; MS (EI, 70 eV) m/z = 395.1 (M + H)+.
Anal. Calcd (%) for C25H22FeO: C, 76.15; H, 5.62. Found: C, 76.24;
H, 5.55.
1-Ferrocenyl-3-phenyl-4-(1-naphthyl)propan-1-one (9): Yield
191.1 mg, 86%; IR (KBr, cm−1) 2921, 1665, 1502, 1448, 1410, 1394,
1
1375, 1251, 1107, 1075, 1022, 1002, 875, 802, 778; H NMR (400
MHz, CDCl3) δ 7.80−7.85 (m, 3H), 7.34−7.49 (m, 8H), 4.78 (s, 2H),
4.46 (s, 2H), 4.08 (s, 5H), 3.09−3.13 (m, 4H); 13C NMR (100 MHz,
CDCl3) δ 203.2, 140.9, 140.3, 138.8, 133.9, 131.8, 128.7, 128.4, 127.6,
127.0, 126.2, 126.0, 125.8, 125.5, 79.2, 72.4, 69.8, 69.4, 41.6, 30.0; MS
(EI, 70 eV) m/z = 445.1 (M + H)+. Anal. Calcd (%) for C29H24FeO:
C, 78.39; H, 5.44. Found: C, 78.23; H, 5.56.
1-Ferrocenyl-3-(1,4-terphenyl)propan-1-one (10): Yield 197.6
mg, 84%; IR (KBr, cm−1) 2924, 1653, 1485, 1456, 1379, 1270, 1231,
1084, 1028, 1002, 897, 839, 758, 690; 1H NMR (400 MHz, CDCl3) δ
7.59−7.65 (m, 8H), 7.45 (t, J = 7.8 Hz, 2H), 7.39 (d, J = 8.0 Hz, 3H),
4.79 (s, 2H), 4.49 (s, 2H), 4.10 (s, 5H), 3.09 (t, J = 4.0 Hz, 4H); 13C
NMR (100 MHz, CDCl3) δ 203.1, 140.9, 140.7, 140.0, 139.9, 138.7,
129.1, 128.8, 127.5, 127.4, 127.3, 127.1, 127.0, 79.0, 72.3, 69.7, 69.3,
41.4, 29.8; MS (EI, 70 eV) m/z = 471.1 (M + H)+. Anal. Calcd (%) for
C31H26FeO: C, 79.16; H, 5.57. Found: C, 79.33; H, 5.45.
1-Ferrocenyl-3-(4-methylphenyl)propan-1-one (2): Yield
161.1 mg, 97%; IR (KBr, cm−1) 2921, 1652, 1515, 1452, 1378,
1255, 1105, 1023, 1002, 817, 809; 1H NMR (400 MHz, CDCl3) δ 7.17
(d, J = 7.8 Hz, 2H), 7.11 (d, J = 7.8 Hz, 2H), 4.75 (s, 2H), 4.46 (s,
2H), 4.08 (s, 5H), 2.99 (s, 4H), 2.31 (s, 3H); 13C NMR (100 MHz,
CDCl3) δ 203.4, 138.7, 135.8, 129.3, 128.6, 79.1, 72.3, 69.8, 69.4, 41.8,
29.9, 21.6; MS (EI, 70 eV) m/z = 333.1 (M + H)+. Anal. Calcd (%) for
C20H20FeO: C, 72.31; H, 6.07. Found: C, 72.50; H, 5.92.
1-Ferrocenyl-3-(4-methylbiphenyl)propan-1-one (11): Yield
181.7 mg, 89%; IR (KBr, cm−1) 2918, 1657, 1498, 1449, 1375, 1264,
1
1223, 1108, 1079, 1037, 1002, 896, 822, 808, 742; H NMR (400
MHz, CDCl3) δ 7.53 (d, J = 8.0 Hz, 2H), 7.46 (d, J = 8.0 Hz, 2H),
7.34 (d, J = 8.0 Hz, 2H), 7.22 (d, J = 8.0 Hz, 2H), 4.77 (s, 2H), 4.48
(s, 2H), 4.09 (s, 5H), 3.06 (s, 4H), 2.38 (s, 3H); 13C NMR (100 MHz,
CDCl3) δ 203.1, 140.4, 139.1, 138.1, 136.8, 129.4, 128.9, 127.0, 126.8,
78.9, 72.2, 69.7, 69.2, 41.4, 29.7, 21.1; MS (EI, 70 eV) m/z = 409.1 (M
F
dx.doi.org/10.1021/jo401421b | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
+ H)+. Anal. Calcd (%) for C26H24FeO: C, 76.48; H, 5.92. Found: C,
76.32; H, 5.99.
arylboronic acids (0.75 mmol), Cs2CO3 (1.0 mmol), and Pd(OAc)2
(0.015 mmol) were added to it under nitrogen. The mixture was
heated at 110 °C for another 12 h. After removal of the solvent, the
residue was purified by column chromatography on silica gel using
CH2Cl2 as eluent to give the red solid 6-aryl-2-ferrocenylquinolines
19−34. Eluent CH2Cl2/ethyl acetate (2:1) for 35−40.
2-Ferrocenyl-6-phenylquinoline (19): Yield 171.1 mg, 91%; IR
(KBr, cm−1) 2961, 1593, 1575, 1499, 1485, 1449, 1378, 1337, 1260,
1093, 1020, 799, 757, 691; 1H NMR (400 MHz, CDCl3) δ 8.05−8.12
(m, 2H), 7.92 (d, J = 6.4 Hz, 2H), 7.71 (d, J = 7.6 Hz, 2H), 7.58 (d, J
= 8.4 Hz, 1H), 7.48 (t, J = 7.2 Hz, 2H), 7.38 (t, J = 7.2 Hz, 1H), 5.08
(s, 2H), 4.47 (s, 2H), 4.06 (s, 5H); 13C NMR (100 MHz, CDCl3) δ
159.7, 147.8, 140.8, 138.3, 135.8, 129.5, 129.2, 129.1, 127.6, 127.4,
127.0, 125.4, 120.0, 84.0, 70.6, 69.8, 68.1; MS (EI, 70 eV) m/z = 390.1
(M + H)+. Anal. Calcd (%) for C25H19FeN: C, 77.14; H, 4.92; N, 3.60.
Found: C, 77.27; H, 4.81; N, 3.69.
2-Ferrocenyl-6-(1-naphthyl)quinoline (20): Yield 197.7 mg,
90%; IR (KBr, cm−1) 2922, 1595, 1498, 1379, 1282, 1105, 1092, 1016,
1001, 819, 791, 773, 734; 1H NMR (400 MHz, CDCl3) δ 8.14 (d, J =
8.4 Hz, 1H), 8.03 (d, J = 8.4 Hz, 1H), 7.88−7.96 (m, 3H), 7.79−7.84
(m, 2H), 7.41−7.61 (m, 5H), 5.11 (s, 2H), 4.48 (s, 2H), 4.08 (s, 5H);
13C NMR (100 MHz, CDCl3) δ 159.9, 147.8, 139.8, 138.1, 135.7,
134.0, 132.1, 131.8, 128.8, 128.5, 128.0, 127.4, 126.8, 126.4, 126.1,
126.0, 125.9, 125.6, 120.0, 84.0, 70.6, 69.8, 68.2; MS (EI, 70 eV) m/z =
440.1 (M + H)+. Anal. Calcd (%) for C29H21FeN: C, 79.28; H, 4.82;
N, 3.19. Found: C, 79.17; H, 4.76; N, 3.32.
1-Ferrocenyl-3-(4-methoxybiphenyl)propan-1-one (12):
Yield 190.9 mg, 90%; IR (KBr, cm−1) 2939, 1658, 1606, 1498, 1450,
1406, 1374, 1248, 1222, 1181, 1109, 1079, 1035, 899, 817, 800, 749;
1H NMR (400 MHz, CDCl3) δ 7.50 (d, J = 8.2 Hz, 4H), 7.33 (d, J =
8.0 Hz, 2H), 6.95 (d, J = 8.0 Hz, 2H), 4.78 (s, 2H), 4.48 (s, 2H), 4.09
(s, 5H), 3.83 (s, 3H), 3.06 (s, 4H); 13C NMR (100 MHz, CDCl3) δ
203.4, 159.2, 140.2, 138.9, 133.7, 129.1, 128.2, 127.0, 114.3, 79.1, 72.4,
69.9, 69.4, 55.5, 41.6, 29.9; MS (EI, 70 eV) m/z = 425.1 (M + H)+.
Anal. Calcd (%) for C26H24FeO2: C, 73.60; H, 5.70. Found: C, 73.74;
H, 5.58.
1-Ferrocenyl-3-(3-methoxybiphenyl)propan-1-one (13):
Yield 180.3 mg, 85%; IR (KBr, cm−1) 2931, 1660, 1608, 1580, 1479,
1
1447, 1407, 1374, 1251, 1208, 1168, 1106, 1054, 870, 827, 776; H
NMR (400 MHz, CDCl3) δ 7.54 (d, J = 7.8 Hz, 2H), 7.34 (d, J = 7.4
Hz, 2H), 7.15 (d, J = 7.6 Hz, 1H), 7.10 (s, 1H), 6.87 (d, J = 7.6 Hz,
1H), 6.48 (t, J = 8.0 Hz, 1H), 4.77 (s, 2H), 4.48 (s, 2H), 4.09 (s, 5H),
3.84 (s, 3H), 3.07 (s, 4H); 13C NMR (100 MHz, CDCl3) δ 203.5,
160.0, 142.6, 141.0, 139.1, 129.8, 129.1, 127.4, 119.6, 112.9, 112.5,
79.0, 72.4, 69.8, 69.4, 55.4, 41.5, 29.9; MS (EI, 70 eV) m/z = 425.1 (M
+ H)+. Anal. Calcd (%) for C26H24FeO2: C, 73.60; H, 5.70. Found: C,
73.77; H, 5.56.
3-(4-Acetylbiphenyl)-1-ferrocenylpropan-1-one (14): Yield
170.2 mg, 78%; IR (KBr, cm−1) 2923, 1678, 1656, 1601, 1451,
1
1376, 1355, 1265, 1227, 1107, 1079, 1003, 898, 811, 730; H NMR
2-Ferrocenyl-6-(2-naphthyl)quinoline (21): Yield 193.3 mg,
(400 MHz, CDCl3) δ 8.01 (d, J = 8.0 Hz, 2H), 7.66 (d, J = 8.0 Hz,
2H), 7.58 (d, J = 8.0 Hz, 2H), 7.40 (d, J = 8.0 Hz, 2H), 4.78 (s, 2H),
4.49 (s, 2H), 4.10 (s, 5H), 3.08 (br, 4H), 2.63 (s, 3H); 13C NMR (100
MHz, CDCl3) δ 203.1, 197.9, 145.7, 142.1, 137.9, 135.9, 129.4, 129.1,
127.5, 127.2, 79.1, 72.4, 69.9, 69.4, 41.4, 29.9, 26.8; MS (EI, 70 eV) m/
z = 437.1 (M + H)+. Anal. Calcd (%) for C27H24FeO2: C, 74.32; H,
5.54. Found: C, 74.18; H, 5.70.
1-Ferrocenyl-3-(3-methoxycarbonylbiphenyl)propan-1-one
(15): Yield 162.9 mg, 72%; IR (KBr, cm−1) 2949, 1712, 1668, 1453,
1443, 1403, 1380, 1384, 1309, 1242, 1227, 1104, 1087, 1022, 896, 812,
759; 1H NMR (400 MHz, CDCl3) δ 8.26 (s, 1H), 7.99 (d, J = 7.6 Hz,
1H), 7.76 (d, J = 7.6 Hz, 1H), 7.58 (d, J = 7.6 Hz, 2H), 7.49 (t, J = 8.0
Hz, 1H), 7.39 (d, J = 8.0 Hz, 2H), 4.78 (s, 2H), 4.49 (s, 2H), 4.10 (s,
5H), 3.94 (s, 3H), 3.08 (t, J = 4.0 Hz, 4H); 13C NMR (100 MHz,
CDCl3) δ 203.2, 167.2, 141.4, 138.1, 131.6, 130.8, 129.3, 128.9, 128.7,
128.3, 128.2, 127.4, 52.3, 41.5, 29.9; MS (EI, 70 eV) m/z = 453.1 (M +
H)+. Anal. Calcd (%) for C27H24FeO3: C, 71.69; H, 5.35. Found: C,
71.81; H, 5.17.
88%; IR (KBr, cm−1) 2922, 1589, 1502, 1455, 1379, 1272, 1103, 1095,
1
1000, 878, 842, 812, 742; H NMR (400 MHz, CDCl3) δ 8.10−8.15
(m, 3H), 8.06 (s, 2H), 7.95 (t, J = 9.2 Hz, 2H), 7.88 (m, 2H), 7.61 (d,
J = 8.4 Hz, 1H), 7.52 (br, 2H), 5.10 (s, 2H), 4.49 (s, 2H), 4.08 (s,
5H); 13C NMR (100 MHz, CDCl3) δ 159.9, 147.9, 138.2, 135.9,
133.9, 132.9, 129.5, 129.4, 128.8, 128.4, 127.9, 127.1, 126.6, 126.5,
126.3, 126.2, 125.7, 125.6, 120.1, 83.9, 70.7, 69.9, 68.2; MS (EI, 70 eV)
m/z = 440.1 (M + H)+. Anal. Calcd (%) for C29H21FeN: C, 79.28; H,
4.82; N, 3.19. Found: C, 79.37; H, 4.68; N, 3.25.
6-Biphenyl-2-ferrocenylquinoline (22): Yield 202.5 mg, 87%;
IR (KBr, cm−1) 2924, 1596, 1499, 1485, 1400, 1337, 1262, 1104, 1093,
1026, 1000, 889, 826, 763; 1H NMR (400 MHz, CDCl3) δ 8.07−8.14
(m, 2H), 7.98 (s, 2H), 7.81 (d, J = 7.6 Hz, 2H), 7.73 (d, J = 7.6 Hz,
2H), 7.67 (d, J = 7.2 Hz, 2H), 7.59 (d, J = 8.4 Hz, 1H), 7.48 (d, J = 7.2
Hz, 2H), 7.38 (t, J = 7.2 Hz, 1H), 5.10 (s, 2H), 4.49 (s, 2H), 4.08 (s,
5H); 13C NMR (100 MHz, CDCl3) δ 159.8, 147.9, 140.8, 140.5,
139.6, 137.7, 135.8, 135.6, 129.6, 129.1, 129.0, 127.8, 127.6, 127.5,
127.2, 127.1, 125.3, 120.1, 119.6, 84.0, 70.6, 69.8, 68.1; MS (EI, 70 eV)
m/z = 466.1 (M + H)+. Anal. Calcd (%) for C31H23FeN: C, 80.01; H,
4.98; N, 3.01. Found: C, 80.13; H, 4.82; N, 3.09.
1-Ferrocenyl-3-(3-nitrobiphenyl)propan-1-one (16): Yield
138.4 mg, 63%; IR (KBr, cm−1) 2929, 1660, 1527, 1518, 1455,
1
1408, 1347, 1255, 1105, 1076, 1029, 867, 833, 737, 721; H NMR
2-Ferrocenyl-6-(4-methylphenyl)quinoline (23): Yield 185.5
mg, 92%; IR (KBr, cm−1) 2919, 1592, 1516, 1499, 1377, 1335, 1284,
1181, 1105, 1012, 914, 858, 824; 1H NMR (400 MHz, CDCl3) δ 8.06
(t, J = 9.6 Hz, 2H), 7.91 (d, J = 7.6 Hz, 2H), 7.62 (d, J = 7.6 Hz, 2H),
7.56 (d, J = 8.4 Hz, 1H), 7.29 (d, J = 7.6 Hz, 2H), 5.07 (s, 2H), 4.47
(s, 2H), 4.06 (s, 5H), 2.41 (s, 3H); 13C NMR (100 MHz, CDCl3) δ
159.5, 147.8, 138.2, 137.4, 135.7, 129.8, 129.5, 129.1, 127.3, 127.0,
125.0, 119.9, 84.2, 70.6, 69.8, 69.1, 21.3; MS (EI, 70 eV) m/z = 404.1
(M + H)+. Anal. Calcd (%) for C26H21FeN: C, 77.43; H, 5.25; N, 3.47.
Found: C, 77.56; H, 5.14; N, 3.53.
(400 MHz, CDCl3) δ 8.43 (s, 1H), 8.17 (d, J = 8.0 Hz, 1H), 7.88 (d, J
= 8.0 Hz, 1H), 7.60 (d, J = 8.0 Hz, 3H), 7.43 (d, J = 7.6 Hz, 2H), 4.79
(s, 2H), 4.50 (s, 2H), 4.10 (s, 5H), 3.10 (t, J = 6.0 Hz, 4H); 13C NMR
(100 MHz, CDCl3) δ 203.1, 148.9, 142.8, 142.5, 136.7, 133.0, 129.8,
129.6, 128.4, 127.4, 121.9, 79.0, 72.5, 69.9, 69.4, 41.3, 29.8; MS (EI, 70
eV) m/z = 440.1 (M + H)+. Anal. Calcd (%) for C25H21FeNO3: C,
68.35; H, 4.82; N, 3.19. Found: C, 68.48; H, 4.61; N, 3.32.
1-Ferrocenyl-3-(pyridin-3-ylphenyl)propan-1-one (17): Yield
110.7 mg, 56%; IR (KBr, cm−1) 2925, 1659, 1454, 1408, 1390, 1255,
1
1105, 1079, 1027, 1001, 880, 822, 806, 716; H NMR (400 MHz,
2-Ferrocenyl-6-(4-methoxyphenyl)quinoline (24): Yield 195.0
mg, 93%; IR (KBr, cm−1) 2918, 1607, 1517, 1501, 1458, 1283, 1242,
1177, 1104, 1024, 818; 1H NMR (400 MHz, CDCl3) δ 8.02−8.07 (m,
2H), 7.87 (d, J = 12.4 Hz, 2H), 7.64 (d, J = 8.2 Hz, 2H), 7.55 (d, J =
12.4 Hz, 1H), 7.01 (d, J = 8.2 Hz, 2H), 5.06 (s, 2H), 4.46 (s, 2H), 4.05
(s, 5H), 3.85 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 159.5, 159.4,
147.6, 137.9, 135.6, 133.3, 129.5, 129.0, 128.5, 127.1, 124.6, 119.9,
114.5, 84.1, 70.5, 69.8, 68.1, 55.5; MS (EI, 70 eV) m/z = 420.1 (M +
H)+. Anal. Calcd (%) for C26H21FeNO: C, 74.48; H, 5.05; N, 3.34.
Found: C, 74.62; H, 4.91; N, 3.46.
CDCl3) δ 8.82 (s, 1H), 8.55 (s, 1H), 7.83 (d, J = 7.2 Hz, 1H), 7.51 (d,
J = 7.2 Hz, 2H), 7.39 (d, J = 7.2 Hz, 2H), 4.76 (s, 2H), 4.47 (s, 2H),
4.08 (s, 5H), 3.07 (s, 4H); 13C NMR (100 MHz, CDCl3) δ 203.1,
148.5, 148.4, 141.9, 136.6, 135.9, 134.3, 129.6, 127.4, 123.7,79.1, 72.4,
69.9, 69.4, 41.4, 29.9; MS (EI, 70 eV) m/z = 396.1 (M + H)+. Anal.
Calcd (%) for C24H21FeNO: C, 72.93; H, 5.35; N, 3.54. Found: C,
72.85; H, 5.26; N, 3.68.
General Procedure for Synthesis of 6-Aryl-2-ferrocenyl-
quinolines. In a Schlenk tube, a mixture of the acetylferrocene (0.5
mmol), (2-amino-5-bromophenyl)methanol (0.6 mmol), KOH (0.5
mmol), and 1 (0.01 mmol) in dioxane (3 mL) was evacuated and
charged with nitrogen. The mixture was heated at 110 °C for 12 h and
then allowed to cool to room temperature. The vessel was opened, and
6-(4-Bromophenyl)-2-ferrocenylquinoline (25): Yield 199.0
mg, 85%; IR (KBr, cm−1) 2917, 1597, 1557, 1508, 1423, 1260,
1
1103, 1091, 1022, 906, 811, 757; H NMR (400 MHz, CDCl3) δ
G
dx.doi.org/10.1021/jo401421b | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
8.02−8.08 (m, 3H), 7.74 (d, J = 7.6 Hz, 2H), 7.65 (m, 1H), 7.57 (m,
2H), 7.44−7.49 (m, 2H), 5.07 (s, 2H), 4.46 (s, 2H), 4.05 (s, 5H); 13C
NMR (100 MHz, CDCl3) δ 159.7, 148.4, 135.6, 132.2, 129.5, 129.1,
129.0, 128.9, 128.7, 127.6, 126.8, 125.5, 119.6, 84.1, 70.5, 69.8, 68.1;
MS (EI, 70 eV) m/z = 468.0 (M + H)+. Anal. Calcd (%) for
C25H18BrFeN: C, 64.14; H, 3.88; N, 2.99. Found: C, 64.28; H, 3.75;
N, 3.10.
1094, 1005, 842, 818, 761; 1H NMR (400 MHz, CDCl3) δ 8.06 (d, J =
8.4 Hz, 2H), 8.02 (d, J = 8.4 Hz, 2H), 7.64 (d, J = 10.4 Hz, 2H), 7.57
(d, J = 8.4 Hz, 1H), 7.29−7.33 (m, 4H), 5.08 (s, 2H), 4.47 (s, 2H),
4.07 (s, 5H), 2.33 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 159.6,
147.5, 141.5, 139.2, 135.6, 131.4, 130.6, 128.6, 127.6, 127.5, 126.6,
126.0, 119.9, 84.1, 70.6, 69.8, 68.1, 20.7; MS (EI, 70 eV) m/z = 404.1
(M + H)+. Anal. Calcd (%) for C26H21FeN: C, 77.43; H, 5.25; N, 3.47.
Found: C, 77.51; H, 5.12; N, 3.56.
2-Ferrocenyl-6-(4-fluorophenyl)quinoline (26): Yield 169.0
mg, 83%; IR (KBr, cm−1) 2924, 1599, 1514, 1499, 1411, 1281,
2-Ferrocenyl-6-(2-methoxyphenyl)quinoline (33): Yield 148.9
1
mg, 71%; IR (KBr, cm−1) 2921, 1596, 1506, 1484, 1455, 1253, 1179,
1218, 1160, 1106, 1001, 816; H NMR (400 MHz, CDCl3) δ 8.05−
1
8.11 (m, 2H), 7.87 (br, 2H), 7.65−7.69 (m, 2H), 7.58 (d, J = 8.4 Hz,
1H), 7.18 (t, J = 8.4 Hz, 2H), 5.09 (s, 2H), 4.49 (s, 2H), 4.07 (s, 5H);
13C NMR (100 MHz, CDCl3) δ 163.9, 161.5, 159.8, 147.8, 137.2,
136.9, 135.6, 129.6, 129.0, 125.3, 120.1, 116.0, 115.8, 84.0, 70.7, 69.8,
68.1; MS (EI, 70 eV) m/z = 408.1 (M + H)+. Anal. Calcd (%) for
C25H18FFeN: C, 73.73; H, 4.45; N, 3.44. Found: C, 73.64; H, 4.37; N,
3.62.
1115, 1028, 817, 754; H NMR (400 MHz, CDCl3) δ 8.04−8.07 (m,
2H), 7.88 (s, 2H), 7.57 (d, J = 8.4 Hz, 1H), 7.44 (d, J = 7.2 Hz, 1H),
7.36 (t, J = 7.6 Hz, 1H), 7.08 (t, J = 7.2 Hz, 1H), 7.03 (d, J = 8.2 Hz,
1H), 5.09 (s, 2H), 4.47 (s, 2H), 4.06 (s, 5H), 3.85 (s, 3H); 13C NMR
(100 MHz, CDCl3) δ 159.5, 156.8, 147.6, 135.9, 135.7, 131.8, 131.2,
130.3, 129.0, 1228.4, 127.8, 126.7, 121.1, 119.6, 111.5, 84.2, 70.5, 69.8,
68.1, 55.8; MS (EI, 70 eV) m/z = 420.1 (M + H)+. Anal. Calcd (%) for
C26H21FeNO: C, 74.48; H, 5.05; N, 3.34. Found: C, 74.42; H, 4.94; N,
3.47.
6-(4-Acetylphenyl)-2-ferrocenylquinoline (27): Yield 170.4
mg, 79%; IR (KBr, cm−1) 2921, 1673, 1595, 1499, 1413, 1356,
1273, 1258, 1196, 1104, 1014, 961, 821; 1H NMR (400 MHz, CDCl3)
δ 8.06−8.13 (m, 2H), 7.92−7.97 (m, 2H), 7.80 (d, J = 7.6 Hz, 2H),
7.59 (d, J = 8.4 Hz, 1H), 5.09 (s, 2H), 4.50 (s, 2H), 4.07 (s, 5H), 2.65
(s, 3H); 13C NMR (100 MHz, CDCl3) δ 197.8, 160.4, 148.2, 145.3,
136.8, 136.1, 135.8, 129.8, 129.2, 128.8, 127.5, 126.9, 126.0, 120.2,
83.8, 70.8, 69.8, 68.2, 26.8; MS (EI, 70 eV) m/z = 432.1 (M + H)+.
Anal. Calcd (%) for C27H21FeNO: C, 75.19; H, 4.91; N, 3.25. Found:
C, 75.33; H, 4.88; N, 3.41.
2-Ferrocenyl-6-(3-methoxyphenyl)quinoline (28): Yield 186.6
mg. 89%; IR (KBr, cm−1) 2924, 1595, 1578, 1502, 1479, 1212, 1174,
1104, 1092, 815, 761; 1H NMR (400 MHz, CDCl3) δ 8.09 (d, J = 9.2
Hz, 1H), 8.04 (d, J = 8.8 Hz, 1H), 7.91 (s, 2H), 7.56 (d, J = 8.4 Hz,
1H), 7.39 (t, J = 7.6 Hz, 1H), 7.29 (d, J = 7.6 Hz, 2H), 7.24 (s, 1H),
6.92 (d, J = 8.0 Hz, 1H), 5.07 (s, 2H), 4.46 (s, 2H), 4.05 (s, 5H), 3.87
(s, 3H); 13C NMR (100 MHz, CDCl3) δ 160.2, 159.7, 147.9, 142.3,
138.1, 135.7, 130.0, 129.5, 129.2, 126.9, 125.5, 120.0, 119.9, 113.2,
113.0, 84.0, 70.6, 69.8, 68.1, 55.5; MS (EI, 70 eV) m/z = 420.1 (M +
H)+. Anal. Calcd (%) for C26H21FeNO: C, 74.48; H, 5.05; N, 3.34.
Found: C, 74.59; H, 4.93; N, 3.42.
6-(2,6-Dimethylphenyl)-2-ferrocenylquinoline (34): Yield 89.7
mg, 43%; IR (KBr, cm−1) 2922, 1595, 1503, 1470, 1378, 1282, 1179,
1129, 1106, 1092, 1001, 891, 819, 769; 1H NMR (400 MHz, CDCl3) δ
8.08 (d, J = 8.4 Hz, 1H), 8.02 (d, J = 8.4 Hz, 1H), 7.59 (d, J = 8.4 Hz,
1H), 7.52 (d, J = 6.4 Hz, 1H), 7.46 (dd, J = 8.4 Hz, 1H), 7.20 (d, J =
7.0 Hz, 1H), 7.15 (d, J = 6.8 Hz, 2H), 5.08 (s, 2H), 4.48 (s, 2H), 4.10
(s, 5H), 2.08 (s, 6H); 13C NMR (100 MHz, CDCl3) δ 159.5, 147.3,
141.2, 138.3, 136.2, 135.4, 131.3, 129.0, 127.4, 127.3, 127.2, 126.8,
119.5, 84.1, 70.4, 69.7, 68.0, 21.0; MS (EI, 70 eV) m/z = 418.1 (M +
H)+. Anal. Calcd (%) for C27H23FeN: C, 77.71; H, 5.56; N, 3.36.
Found: C, 77.85; H, 5.43; N, 3.29.
2-Ferrocenyl-6-pyridin-3-ylquinoline (35): Yield 163.9 mg,
84%; IR (KBr, cm−1) 2928, 1596, 1503, 1475, 1420, 1396, 1340,
1
1247, 1180, 1105, 1050, 1016, 822, 801, 707; H NMR (400 MHz,
CDCl3) δ 8.97 (s, 1H), 8.63 (d, J = 7.6 Hz, 1H), 8.13 (d, J = 8.4 Hz,
1H), 8.07 (d, J = 8.4 Hz, 1H), 7.97 (d, J = 7.6 Hz, 1H), 7.91(s, 1H),
7.87 (d, J = 8.8 Hz, 1H), 7.58 (d, J = 8.4 Hz, 1H), 7.39 (t, J = 6.0 Hz,
1H), 5.08 (s, 2H), 4.48 (s, 2H), 4.06 (s, 5H); 13C NMR (100 MHz,
CDCl3) δ 160.3, 148.7, 148.5, 148.1, 136.2, 135.7, 134.7, 134.5, 130.0,
128.6, 126.9, 125.8, 123.8, 120.2, 83.7, 70.7, 69.8, 68.1; MS (EI, 70 eV)
m/z = 391.1 (M + H)+. Anal. Calcd (%) for C24H18FeN2: C, 73.86; H,
4.65; N, 7.18. Found: C, 73.97; H, 4.52; N, 7.24.
2-Ferrocenyl-6-(3-methoxycarbonylphenyl)quinoline (29):
Yield 185.3 mg, 83%; IR (KBr, cm−1) 2946, 1718, 1596, 1580, 1504,
1
1430, 1303, 1236, 1104, 1085, 818, 755, 692; H NMR (400 MHz,
CDCl3) δ 8.41 (s, 1H), 8.05−8.13 (m, 3H), 7.90−7.98 (m, 3H),
7.54−7.61 (m, 2H), 5.09 (s, 2H), 4.49 (s, 2H), 4.07 (s, 5H), 3.97 (s,
3H); 13C NMR (100 MHz, CDCl3) δ 167.2, 160.1, 148.0, 141.1,
137.1, 135.8, 131.8, 131.0, 129.8, 129.2, 128.9, 128.7, 128.5, 127.0,
125.7, 120.2, 83.9, 70.7, 69.8, 68.2, 52.4; MS (EI, 70 eV) m/z = 448.1
(M + H)+. Anal. Calcd (%) for C27H21FeNO2: C, 72.50; H, 4.73; N,
3.13. Found: C, 72.67; H, 4.54; N, 3.19.
2-Ferrocenyl-6-(3-nitrylphenyl)quinoline (30): Yield 175.9 mg,
81%; IR (KBr, cm−1) 2922, 1597, 1525, 1499, 1347, 1282, 1137, 1093,
1000, 888, 845, 818, 763; 1H NMR (400 MHz, CDCl3) δ 8.58 (s, 1H),
8.22 (d, J = 8.0 Hz, 1H), 8.08−8.15 (m, 2H), 8.03 (d, J = 7.6 Hz, 1H),
7.98 (s, 1H), 7.92 (d, J = 8.8 Hz, 1H), 7.60−7.66(m, 2H), 5.09 (s,
2H), 4.51 (s, 2H), 4.08 (s, 5H); 13C NMR (100 MHz, CDCl3) δ
160.7, 149.0, 148.3, 142.5, 135.8, 135.5, 133.2, 130.1, 130.0, 128.5,
126.9, 126.0, 122.3, 122.1, 120.4, 83.7, 70.8, 69.9, 68.2; MS (EI, 70 eV)
m/z = 435.1 (M + H)+. Anal. Calcd (%) for C25H18FeN2O2: C, 69.14;
H, 4.18; N, 6.45. Found: C, 69.07; H, 4.09; N, 6.63.
2-Ferrocenyl-6-pyridin-4-ylquinoline (36): Yield 148.3 mg,
76%; IR (KBr, cm−1) 2925, 1595, 1501, 1420, 1396, 1340, 1246,
1104, 1093, 1016, 891, 821, 801, 706; 1H NMR (400 MHz, CDCl3) δ
8.71 (d, J = 4.8 Hz, 2H), 8.09−8.15 (m, 2H), 8.01 (d, J = 2.8 Hz, 1H),
7.92−7.95 (m, 1H), 7.61−7.65 (m, 3H), 5.10 (s, 2H), 4.51 (s, 2H),
4.08 (s, 5H); 13C NMR (100 MHz, CDCl3) δ 160.7, 150.4, 148.5,
147.8, 135.8, 134.8, 129.9, 128.1, 126.7, 126.0, 121.7, 120.2, 83.5, 70.8,
69.8, 68.1; MS (EI, 70 eV) m/z = 391.1 (M + H)+. Anal. Calcd (%) for
C24H18FeN2: C, 73.86; H, 4.65; N, 7.18. Found: C, 73.99; H, 4.54; N,
7.11.
2-Ferrocenyl-6-(3-methoxycarbonylpyridin-4-yl)quinoline
(37): Yield 156.9 mg, 70%; IR (KBr, cm−1) 2927, 1715, 1593, 1501,
1
1440, 1416, 1303, 1259, 1106, 1012, 918, 829, 808, 742; H NMR
(400 MHz, CDCl3) δ 8.82 (d, J = 8.4 Hz, 1H), 8.52 (s, 1H), 8.08−
8.16 (m, 3H), 7.97 (d, J = 8.4 Hz, 1H), 7.82 (br, 1H), 7.62 (d, J = 8.4
Hz, 1H), 5.10 (s, 2H), 4.52 (s, 2H), 4.08 (s, 8H); 13C NMR (100
MHz, CDCl3) δ 166.0, 161.2, 150.3, 149.2, 148.8, 148.7, 135.9, 130.2,
127.9, 126.8, 126.4, 124.7, 123.2, 120.5, 83.5, 70.9, 69.9, 68.2, 53.2; MS
(EI, 70 eV) m/z = 449.1 (M + H)+. Anal. Calcd (%) for
C26H20FeN2O2: C, 69.66; H, 4.50; N, 6.25. Found: C, 69.85; H,
4.41; N, 6.17.
6-(3,5-Dimethylphenyl)-2-ferrocenylquinoline (31): Yield
189.9 mg, 91%; IR (KBr, cm−1) 2918, 1667, 1592, 1501, 1379,
1
1278, 1242, 1133, 1093, 1001, 885, 831, 819, 697; H NMR (400
MHz, CDCl3) δ 8.09 (t, J = 10.0 Hz, 2H), 7.5 (br, 2H), 7.94 (d, J = 8.4
Hz, 1H), 7.36 (s, 2H), 7.05 (1, 1H), 5.10 (s, 2H), 4.49 (s, 2H), 4.09 (s,
5H), 2.43 (s, 6H); 13C NMR (100 MHz, CDCl3) δ 159.5, 147.8,
140.7, 138.6, 138.5, 135.7, 129.4, 129.3, 129.2, 127.0, 125.4, 125.3,
119.9, 84.1, 70.6, 69.8, 68.1, 21.6; MS (EI, 70 eV) m/z = 418.1 (M +
H)+. Anal. Calcd (%) for C27H23FeN: C, 77.71; H, 5.56; N, 3.36.
Found: C, 77.84; H, 5.47; N, 3.31.
2-Ferrocenyl-6-(5-ethoxycarbonylpyridin-3-yl)quinoline
(38): Yield 184.9 mg, 80%; IR (KBr, cm−1) 2923, 1714, 1597, 1504,
1
1455, 1368, 1291, 1239, 1162, 1104, 1023, 835, 823, 807; H NMR
(400 MHz, CDCl3) δ 9.23 (s, 1H), 9.12 (s, 1H), 8.60 (s, 1H), 8.13 (d,
J = 8.4 Hz, 1H), 8.09 (d, J = 8.4 Hz, 1H), 7.98 (s, 1H), 7.92 (d, J = 8.8
Hz, 1H), 7.61 (d, J = 8.4 Hz, 1H), 5.09 (s, 2H), 4.46−4.50 (m, 4H),
4.07 (s, 5H), 1.45 (t, J = 7.0 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ
165.4, 160.7, 151.8, 149.6, 148.2, 136.1, 135.7, 135.4, 133.6, 130.2,
2-Ferrocenyl-6-(2-methylphenyl)quinoline (32): Yield 137.0
mg, 68%; IR (KBr, cm−1) 2922, 1595, 1483, 1455, 1378, 1268, 1104,
H
dx.doi.org/10.1021/jo401421b | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
128.4, 126.9, 126.5, 126.1, 120.3, 83.6, 70.8, 69.8, 68.2, 61.7, 14.4; MS
(EI, 70 eV) m/z = 463.1 (M + H)+. Anal. Calcd (%) for
C27H22FeN2O2: C, 70.14; H, 4.80; N, 6.06. Found: C, 70.27; H,
4.74; N, 6.01.
(6) (a) Kwon, M. S.; Kim, N.; Seo, S. H.; Park, I. S.; Cheedrala, R. K.;
Park, J. Angew. Chem., Int. Ed. 2005, 44, 6913. (b) Cho, C. S. J. Mol.
Catal. A: Chem. 2005, 240, 55. (c) Yamada, Y. M. A.; Uozumi, Y. Org.
Lett. 2006, 8, 1375. (d) Yamada, Y. M. A.; Uozumi, Y. Tetrahedron
2007, 63, 8492.
2-Ferrocenyl-6-(4-methoxypyridin-3-yl)quinoline (39): Yield
182.8 mg, 87%; IR (KBr, cm−1) 2926, 1597, 1567, 1507, 1458, 1407,
(7) (a) Alonso, F.; Riente, P.; Yus, M. Synlett 2007, 1877. (b) Alonso,
F.; Riente, P.; Yus, M. Eur. J. Org. Chem. 2008, 4908.
1
1385, 1341, 1284, 1134, 1091, 1027, 993, 915, 822, 752; H NMR
(400 MHz, CDCl3) δ 8.51 (s, 1H), 8.05−8.10 (m, 2H), 7.90 (d, J =
8.4 Hz, 1H), 7.83 (d, J = 9.2 Hz, 2H), 7.58 (d, J = 8.4 Hz, 1H), 6.86
(d, J = 8.4 Hz, 1H), 5.07 (s, 2H), 4.48 (s, 2H), 4.06 (s, 5H), 4.00 (s,
3H); 13C NMR (100 MHz, CDCl3) δ 163.9, 159.9, 147.8, 145.4,
137.7, 135.6, 135.0, 129.8, 129.7, 128.6, 127.1, 124.9, 120.1, 111.1,
83.9, 70.7, 69.8, 68.1, 53.7; MS (EI, 70 eV) m/z = 421.1 (M + H)+.
Anal. Calcd (%) for C25H20FeN2O: C, 71.44; H, 4.80; N, 6.67. Found:
C, 71.60; H, 4.73; N, 6.59.
(8) (a) Oro, L. A.; Claver, C., Eds. Iridium Complexes in Organic
Synthesis; Wiley-VCH: Weinheim, Germany, 2009. (b) Suzuki, T.
Chem. Rev. 2011, 111, 1825.
(9) (a) Onodera, G.; Nishibayashi, Y.; Uemura, S. Angew. Chem., Int.
Ed. 2006, 45, 3819. (b) Saidi, O.; Blacker, A. J.; Farah, M. M.;
Marsden, S. P.; Williams, J. M. J. Chem. Commun. 2010, 1541.
(c) Obora, Y.; Ishii, Y. Synlett 2011, 30.
(10) (a) Taguchi, K.; Nakagawa, H.; Hirabayashi, T.; Sakaguchi, S.;
Ishii, Y. J. Am. Chem. Soc. 2004, 126, 72. (b) Iuchi, Y.; Obora, Y.; Ishii,
Y. J. Am. Chem. Soc. 2010, 132, 2536.
(11) Xu, C.; Dong, X. M.; Wang, Z. Q.; Hao, X. Q.; Li, Z.; Duan, L.
M.; Ji, B. M.; Song, M. P. J. Organomet. Chem. 2012, 700, 214.
(12) Miyaura, N.; Suzuki, A. Chem. Rev. 1995, 95, 2457.
(13) Kealy, T. J.; Pauson, P. L. Nature 1951, 168, 1039.
(14) (a) Togni, A.; Hayashi, T. Ferrocenes; VCH: Weinheim,
Germany, 1995. (b) Staveren, D. R.; Metzler-Nolte, N. Chem. Rev.
2004, 104, 5931. (c) Stepnicka, P.; Ed. Ferrocenes: Ligands, Materials
and Biomolecules; John Wiley & Sons, Inc.: New York, 2008.
(15) (a) Xu, C.; Wang, Z. Q.; Fu, W. J.; Lou, X. H.; Li, Y. F.; Cen, F.
F.; Ma, H. J.; Ji, B. M. Organometallics 2009, 28, 1909. (b) Xu, C.;
Zhang, Y. P.; Wang, Z. Q.; Fu, W. J.; Hao, X. Q.; Xu, Y.; Ji, B. M.
Chem. Commun. 2010, 6852. (c) Xu, C.; Wang, Z. Q.; Li, Z.; Wang, W.
Z.; Hao, X. Q.; Fu, W. J.; Gong, J. F.; Ji, B. M.; Song, M. P.
Organometallics 2012, 31, 798. (d) Li, H. M.; Xu, C.; Hao, X. Q.; Li,
Z.; Wang, Z. Q.; Fu, W. J.; Song, M. P. Inorg. Chim. Acta 2013, 404,
236.
(16) (a) Kuklin, S. A.; Sheloumov, A. M.; Dolgushin, F. M.;
Ezernistskaya, M. G.; Peregudov, A. S.; Petrovskii, P. V.; Koridze, A. A.
Organometallics 2006, 25, 5466. (b) Eum, M. S.; Chin, C. S.; Kim, S.
Y.; Kim, C.; Kang, S. K.; Hur, N. H.; Seo, J. H.; Kim, G. Y.; Kim, Y. K.
Inorg. Chem. 2008, 47, 6289. (c) Punji, B.; Emge, T. J.; Goldman, A. S.
Organometallics 2010, 29, 2702.
6-(4-Dimethylaminopyridin-3-yl)-2-ferrocenylquinoline (40):
Yield 190.7 mg, 88%; IR (KBr, cm−1) 2921, 1605, 1519, 1497, 1393,
1
1332, 1267, 1220, 1103, 1092, 1022, 1012, 842, 804; H NMR (400
MHz, CDCl3) δ 8.56 (s, 1H), 8.01−8.07 (m, 2H), 7.79−7.85 (m, 3H),
7.55 (d, J = 8.4 Hz, 1H), 6.60 (d, J = 8.8 Hz, 1H), 5.06 (s, 2H), 4.46
(s, 2H), 4.05 (s, 5H), 3.14 (s, 6H); 13C NMR (100 MHz, CDCl3) δ
159.2, 158.8, 147.4, 146.5, 135.9, 135.8, 135.5, 129.6, 128.3, 127.2,
123.9, 123.6, 119.9, 105.9, 84.1, 70.5, 69.8, 68.0, 38.3; MS (EI, 70 eV)
m/z = 434.1 (M + H)+. Anal. Calcd (%) for C26H23FeN3: C, 72.07; H,
5.35; N, 9.70. Found: C, 72.21; H, 5.27; N, 9.79.
ASSOCIATED CONTENT
■
S
* Supporting Information
1
Copy of H and 13C NMR spectra for all products. X-ray CIF
files for 1, 9, 13, 23, 29, 32, and 40. This material is available
free of charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
*E-mail: xubohan@163.com (C.X.), maopingsong@zzu.edu.cn
(M.-P.S.).
■
Notes
The authors declare no competing financial interest.
(17) (a) Nishio, M. CrystEngComm 2004, 6, 130. (b) Malathy Sony,
S. M.; Ponnuswamy, M. N. Cryst. Growth Des. 2006, 6, 736.
(18) (a) Jones, G. In Comprehensive Heterocyclic Chemistry II;
Katritzky, A. R., Rees, C. W., Scriven, E. F. V., Eds.; Pergamon: New
York, 1996; Vol. 5, Chapter 5, pp 167−243. (b) Carey, J. S.; Laffan, D.;
Thomson, C.; Williams, M. T. Org. Biomol. Chem. 2006, 4, 2337.
(c) Michael, J. P. Nat. Prod. Rep. 2007, 24, 223.
ACKNOWLEDGMENTS
■
We are grateful to the National Natural Science Foundation of
China (Nos. 21272110, U1204205, and 20902043) for financial
support of this work.
(19) (a) Gelin, F.; Thummel, R. P. J. Org. Chem. 1992, 57, 3780.
(b) Beletskaya, I. P.; Tsvetkov, A. V.; Latyshev, G. V.; Tafeenko, V. A.;
Lukashev, N. V. J. Organomet. Chem. 2001, 637−639, 653.
(c) Kloetzing, R. J.; Knochel, P. Tetrahedron: Asymmetry 2006, 17,
116. (d) Chupakhin, O. N.; Utepova, I. A.; Kovalev, I. S.; Rusinov, V.
L.; Starikova, Z. A. Eur. J. Org. Chem. 2007, 857. (e) Zora, M.;
REFERENCES
■
(1) (a) Zhu, J., Bienaym, H., Eds. Multicomponent Reactions; Wiley-
VCH: Weinheim, Germany, 2005. (b) Ramοn, D. J.; Yus, M. Angew.
Chem., Int. Ed. 2005, 44, 1602. (c) Domling, A. Chem. Rev. 2006, 106,
́
̈
17.
(2) (a) Lee, J. M.; Na, Y.; Han, H.; Chang, S. Chem. Soc. Rev. 2004,
33, 302. (b) Wasilke, J. C.; Obrey, S. J.; Baker, R. T.; Bazan, G. C.
Chem. Rev. 2005, 105, 1001. (c) Zanardi, A.; Corberan, R.; Mata, J. A.;
́
Peris, E. Organometallics 2008, 27, 3570. (d) Zanardi, A.; Mata, J. A.;
Peris, E. J. Am. Chem. Soc. 2009, 131, 14531.
̈
Veliog
(20) Marco-Contelles, J.; Per
̆
́
C.; Soriano, E. Chem. Rev. 2009, 109, 2652.
(21) (a) Cho, C. S.; Kim, B. T.; Kim, T. J.; Shim, S. C. Chem.
Commun. 2001, 2576. (b) Cho, C. S.; Kim, B. T.; Choi, H. J.; Kim, T.
J.; Shim, S. C. Tetrahedron 2003, 59, 7997. (c) Motokura, K.;
Mizugaki, T.; Ebitani, K.; Kaneda, K. Tetrahedron Lett. 2004, 45, 6029.
(d) Taguchi, K.; Sakaguchi, S.; Ishii, Y. Tetrahedron Lett. 2005, 46,
4539.
(22) Snider, B. B.; Ahn, Y.; O’Hare, S. M. Org. Lett. 2001, 3, 4217.
(23) Wu, X.; Tiekink, E. R. T.; Kostetski, I.; Kocherginsky, N.; Tan,
A. L. C.; Khoo, S. B.; Wilairat, P.; Go, M. L. Eur. J. Pharm. Sci. 2006,
27, 175.
(3) (a) Diederich, F., Stang, P. J., Eds. Metal-Catalyzed Cross-Coupling
Reactions; Wiley- VCH: Weinheim, Germany, 1998. (b) Suzuki, A. J.
Organomet. Chem. 2002, 653, 83. (c) Littke, A. F.; Fu, G. C. Angew.
Chem., Int. Ed. 2002, 41, 6338. (d) Altman, R. A.; Buchwald, S. L. Nat.
Protoc. 2007, 2, 3115.
(4) (a) Guillena, G.; Ramon
2007, 46, 2358. (b) Hamid, M. H. S. A.; Slatford, P. A.; Williams, J. M.
J. Adv. Synth. Catal. 2007, 349, 1555. (c) Guillena, G.; Ramon, D. J.;
Yus, M. Chem. Rev. 2010, 110, 1611.
(5) (a) Cho, C. S.; Kim, B. T.; Kim, T. J.; Shim, S. C. Tetrahedron
Lett. 2002, 43, 7987. (b) Martínez, R.; Brand, G. J.; Ramon, D. J.; Yus,
M. Tetrahedron Lett. 2005, 46, 3683. (c) Martínez, R.; Ramon, D. J.;
Yus, M. Tetrahedron 2006, 62, 8988.
́
, D. J.; Yus, M. Angew. Chem., Int. Ed.
́
́
́
I
dx.doi.org/10.1021/jo401421b | J. Org. Chem. XXXX, XXX, XXX−XXX