Pd-catalyzed oxidative coupling of arene C-H bonds with benzylic ethers as acyl equivalents

Article abstract of DOI:10.1021/jo4024304

A palladium-catalyzed oxidative coupling of arene C-H bonds with benzylic ethers via C-H bond activation is described. The reaction proceeds efficiently with a broad range of substrates bearing conventional directing groups with excellent functional group compatibility. This protocol potentially provides opportunities to use dibenzyl ethers as new acyl equivalents for catalytic acylation reactions.

Full text of DOI:10.1021/jo4024304

Article
pubs.acs.org/joc
Pd-Catalyzed Oxidative Coupling of Arene C−H Bonds with Benzylic
Ethers as Acyl Equivalents
Sangil Han,† Satyasheel Sharma,† Jihye Park,† Mirim Kim,† Youngmi Shin,† Neeraj Kumar Mishra,†
Jong Jin Bae,‡ Jong Hwan Kwak,† Young Hoon Jung,† and In Su Kim*,†
†School of Pharmacy, Sungkyunkwan University, Suwon 440-746, Republic of Korea
‡Department of Oriental Pharmacy, Woosuk University, Jeonju 565-701, Republic of Korea
S
* Supporting Information
ABSTRACT: A palladium-catalyzed oxidative coupling of arene C−H bonds with benzylic ethers via C−H bond activation is
described. The reaction proceeds efficiently with a broad range of substrates bearing conventional directing groups with excellent
functional group compatibility. This protocol potentially provides opportunities to use dibenzyl ethers as new acyl equivalents for
catalytic acylation reactions.
functional groups that are widely used in organic synthesis,
including aldehydes, esters, and carboxylic acids. Since the first
report on the formation of benzaldehydes from benzyl methyl
ethers by Markees in 1958,12 a number of methods have been
developed for the formation of benzaldehydes via the oxidative
cleavage of benzylic C−O bonds under various conditions, such
as NBS/H2O,13 TEMPO,14 HNO3,15 Cu(NO3)2,16 and
DDQ.17 However, there has been no report concerning the
behavior of benzylic ethers when treated with tert-butyl
hydroperoxide (TBHP) as a mild oxidant.
As part of an ongoing research program directed toward the
development of catalytic acylation reactions of inactive C−H
bonds, we became interested in developing oxidative acylation
reactions using benzylic ethers. Herein we present the
palladium-catalyzed ortho-acylation of arene C−H bonds with
benzylic ethers in the presence of TBHP to afford aryl ketones.
INTRODUCTION
■
Transition-metal-catalyzed selective cross-coupling reactions via
C−H bond activation have emerged as an attractive alternative
to traditional cross-coupling reactions because of the
minimization of stoichiometric metallic waste and the costs
associated with the preparation of starting materials.1 Thus,
cross-coupling reactions via C−H bond activation can lead to
an improved overall efficiency of the desired transformation.
Since the pioneering efforts of Murai,2 remarkable progress has
been made on carbon−carbon cross-coupling reactions via C−
H bond activation. In particular, most C−H bond activation
processes generally rely on the strategies of directing-group-
assisted C−H bond functionalization and dehydrogenative
cross-coupling.3
Recently, transition-metal-catalyzed oxidative ortho-acylation
reactions between arene C−H bonds bearing conventional
directing groups and aldehydes4 or alcohols5 as acyl sources
have been described (Figure 1). Catalytic decarboxylative
acylations of aromatic C−H bonds using α-oxocarboxylic acids
as acyl surrogates have also been reported.6 Recently, a
palladium-catalyzed acylation of inactive C(sp2)−H bonds via
C−H, C−C, and C−O bond cleavage of toluenes,7 diketones,8
and carboxylic acids9, respectively, was reported. In addition,
Yang and Wu demonstrated a palladium-catalyzed direct C−H
acylation using arylmethyl amines as new acylation reagents.10
Benzylic ethers constitute one of the common protecting
groups for alcohols. The C−O bond of benzylic ethers is readily
cleaved under a variety of either oxidative or reductive
conditions.11 In particular, oxidative reactions of methylene
carbons in benzyl ethers are important transformations because
they can convert chemically stable moieties into reactive
RESULTS AND DISCUSSION
■
In previous reports, O-methyl oxime has been used as an
efficient directing group for C−H bond functionalization. For
example, Shi18 and Cheng19 applied this directing group to
oxidative coupling with arylboronic acids and aryl halides,
respectively. In addition, we described a palladium-catalyzed
oxidative ortho-acylation of O-methyl ketoximes from the
alcohol oxidation level.5d Thus, O-methyl ketoxime 1a was
chosen as a model substrate for the oxidative coupling with
dibenzyl ether (1b), and the selected optimization is
summarized in Table 1. As shown in entries 1−5, a range of
Received: October 31, 2013
© XXXX American Chemical Society
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Figure 1. Acyl equivalents for catalytic acylation of arene C−H bonds.
a
Table 1. Selected Optimization of the Reaction Conditions
b
entry
catalyst (mol %)
oxidant (equiv)
additive (equiv)
solvent
yield (%)
1
2
PdCl2 (5)
TBHP (3)
TBHP (3)
TBHP (3)
TBHP (3)
TBHP (3)
TBHP (3)
DCE
DCE
DCE
DCE
DCE
DCE
DCE
DCE
DCE
DCE
MeCN
THF
DMF
DCE
DCE
DCE
DCE
DCE
DCE
11
Pd(OAc)2 (5)
Pd2(dba)3 (5)
Pd(TFA)2 (5)
Pd(OTf)2 (5)
24
3
N.R.
22
4
5
8
6
N.R.
N.R.
trace
N.R.
N.R.
18
7
Pd(OAc)2 (100)
Pd(OAc)2 (5)
Pd(OAc)2 (5)
Pd(OAc)2 (5)
Pd(OAc)2 (5)
Pd(OAc)2 (5)
Pd(OAc)2 (5)
Pd(OAc)2 (5)
Pd(OAc)2 (5)
Pd(OAc)2 (5)
Pd(OAc)2 (5)
Pd(OAc)2 (5)
Pd(OAc)2 (5)
8
(PhCOO)2 (3)
Cu(OAc)2 (3)
O2 gas
9
10
11
12
13
14
15
16
17
18
19
TBHP (3)
TBHP (3)
TBHP (3)
TBHP (5)
TBHP (5)
TBHP (6)
TBHP (7)
TBHP (6)
TBHP (6)
8
trace
43
AcOH (3)
AcOH (3)
AcOH (3)
AcOH (1)
AcOH (3)
71
85
84
61
48
a
Reaction conditions: 1a (0.3 mmol), 2a (0.9 mmol), Pd catalyst (quantity noted), oxidant (quantity noted), additive (quantity noted), and solvent
b
(1 mL) in pressure tubes. Determined by flash column chromatography.
Pd catalysts were screened in the presence of TBHP (300 mol
%) as an oxidant, and the use of Pd(OAc)2 afforded our
desirable adduct 3a in 24% yield (entry 2). In the absence of
either Pd(OAc)2 or TBHP, no coupling product was observed,
even when 100 mol % Pd(OAc)2 was used without TBHP,
indicating that both reagents are required in the reaction
(entries 6 and 7). Next, our study focused on the use of
oxidants such as (PhCOO)2, Cu(OAc)2, and O2 gas, but the
chemical yield was not improved (entries 8−10). Further
screening of solvents showed that DCE is superior to other
solvents such as MeCN, THF, and DMF (entries 11−13).
Logically, it was thought that the formation of 3a could be
B
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a
Table 2. Scope of Benzylic Ethers
a
Reaction conditions: 1a (0.3 mmol), 2 (0.9 mmol), Pd(OAc)2 (5 mol %), TBHP (6 equiv), AcOH (3 equiv), and DCE (1 mL) at 80 °C for 6 h in
b
c
pressure tubes. Determined by flash column chromatography. 24 h.
increased by increasing the amount of TBHP. Indeed, with 5
equiv of TBHP under otherwise identical conditions, the yield
of 3a was found to be improved to 43% (entry 14). Further
investigation revealed that AcOH as an additive is unique in its
ability to facilitate high levels of conversion (Table 1, entry 15).
After further optimization, the best results were obtained using
a treatment of 5 mol % Pd(OAc)2 and 6 equiv of TBHP in the
presence of 3 equiv of AcOH additive in DCE solvent at 80 °C
for 6 h, which afforded the desired aryl ketone 3a in high yield
(85%; entry 16).
With the optimized reaction conditions in hand, the scope
and limitation of benzylic ethers were explored (Table 2). The
coupling of O-methyl ketoxime 1a and benzylic ethers 2b−h
with electron-donating and electron-withdrawing groups
(OMe, Me, CF3, F, Br, and Cl) was found to be favored in
the acylation reaction, regardless of the position of the
substituent on the aromatic ring, affording the corresponding
products 3b−h in good to high yields. Notably, p-bromobenzyl
ether (2e) was tolerated under these coupling conditions and
offers versatile synthetic functionality for further elaboration. In
addition, 2,2′-oxybis(methylene)dinaphthalene (2i) smoothly
underwent this coupling reaction to generate the corresponding
product 3i. Unfortunately, dialkyl ethers and diallylic ethers
were found to be unreactive and did not provide the
corresponding products.
screened to couple with dibenzyl ether (2a), as shown in Table
3. The reaction of para-substituted O-methyl ketoximes 1c and
1d found to be favored in the acylation reaction, affording the
corresponding products 4c and 4d in high yields, whereas 1e
with a strong electron-withdrawing group (CF3) at the para
position was found to be relatively less reactive under these
reaction conditions. It should be noted that the reaction
exclusively afforded the monoacylated products in all cases, and
1
no bisacylation products were observed by H NMR or GC−
MS analysis. The acylation of meta-substituted O-methyl
ketoximes preferentially occurred at the less sterically hindered
ortho position to afford the corresponding products 3f, 3g, and
3i as single regioisomers. However, m-fluoroacetophenone O-
methyl oxime (1h) afforded a mixture of regioisomers 4h
(48%) and 4h′ (24%) at the C-6 and C-2 positions,
respectively. These results suggest that steric effects of the
substrate strongly interfere with the formation of the
cyclopalladated intermediate. In addition, this transformation
also showed good reactivity toward ortho-substituted O-methyl
ketoxime 1j. Aldoxime 1k provided the corresponding product
4k with significantly decreased reactivity. Notably, in the case of
benozophenone 1l with four ortho-C−H bonds, only
monoacylation took place, providing the corresponding
product 4l in 72% yield. However, unsymmetrical benzophe-
none O-methyl oxime 1m provided no significant distribution
of products 4m and 4m′. After successful exploration of the
scope of oximes in the direct acylation, we turned our attention
To further explore the substrate scope and limitation of this
process, a broad range of arenes with directing groups were
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a
Table 3. Scope of Arenes with Various Directing Groups
a
Reaction conditions: 1 (0.3 mmol), 2a (0.9 mmol), Pd(OAc)2 (5 mol %), TBHP (6 equiv), AcOH (3 equiv), and DCE (1 mL) at 80 °C for 6 h in
b
c
d
pressure tubes. Determined by flash column chromatography. 20 h. Without AcOH.
to substrates bearing various heterocyclic directing groups. We
were pleased to see that representative directing groups such as
2-pyridine, quinoline, and 2-pyrazol (1n−q) facilitated the
ortho-C−H acylation under identical reaction conditions.
Notably, acylated product 4q can be readily converted to the
corresponding o-acylphenol by cleavage of the pyridinyl
moiety.5c In contrast, a wide range of substrates 1r−v forming
five- or six-membered palladacycle intermediates failed to
deliver our desired products under the present reaction
conditions.
To gain mechanistic insight, a series of competition
experiments were performed, as shown in Schemes 1 and 2.
First, an intermolecular competition experiment between
dibenzylic ethers 2a and 2b was conducted under the standard
reaction conditions. Exposure of O-methyl ketoxime 1a to
equimolar quantities of 2a and 2b provided a separable mixture
of 3a and 3b, respectively, in 82% combined yield with a ratio
of 1:2.4 (Scheme 1, eq 1). An intramolecular competition
experiment employing unsymmetrical benzylic ether 2j under
otherwise identical conditions afforded a mixture of 3b and 3c
D
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Scheme 1. Competition Experiments with Dibenzylic Ethers
Scheme 2. Intramolecular Competition Experiments between Arenes with Different Directing Groups
Scheme 3. Mechanistic Investigation by LC−MS Analysis
in 47% yield with a 3.0:1 ratio (Scheme 1, eq 2). These results
indicate that the benzylic position with an electron-rich moiety
may be more rapidly involved in the generation of the acyl
radical intermediate.
To further examine the influence of the directing group on
this process, intramolecular competition experiments between
1b and 1n were performed under the standard reaction
conditions (Scheme 2, eq 1). Interestingly, no acylation of 1b
with an oxime directing group was observed, and 2-phenyl-
pyridine (1n) exclusively furnished the corresponding product
4n in 64% yield. In addition, intramolecular competition
experiments between O-methyl ketoxime 1b and phenoxypyr-
idine 1q afforded a mixture of acylated products 4b and 4q in
93% combined yield with a 1:1.4 ratio (Scheme 2, eq 2). These
observations suggest that the pyridine directing group may
coordinate more favorably to the palladium center rather than
the oxime directing group irrespective of the kinetic stability of
five- or six-membered palladacycles.
E
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Figure 2. Hammett correlation studies.
Scheme 4. Plausible Reaction Mechanism
To support the mechanistic pathway for this reaction, some
related experiments were conducted. The reaction between O-
methyl ketoxime 1a and dibenzyl ether (2a) in the presence of
the radical scavenger ascorbic acid resulted in significantly
reduced formation of the acylated product 3a (<5% yield).4e,20
This result indicates that the acylation reaction may proceed
through a radical pathway. Dibenzylic ether 2b in the presence
of TBHP and Pd(OAc)2 was converted to 4-anisaldehyde and
4-anisic acid as determined by LC−MS analysis. However,
significantly decreased amounts of 4-anisaldehyde and 4-anisic
acid were detected in the absence of Pd(OAc)2.
(5ac), and 4-anisic acid (5ad) as determined by LC−MS
analysis (Scheme 3). These results can be rationalized if the
radical initiator TBHP in the presence of the palladium catalyst
can undergo C−O bond cleavage to generate benzylic radicals,
which may be rapidly oxidized to provide benzoyl radicals in
catalytic cycle. Another possible pathway could involve trapping
of the benzylic radical intermediate by a palladacycle to afford
benzylated product 5ab, which could further undergo fast
oxidation at the benzylic position to generate acylated product
5a.7a,21
The effect of substituents on the reaction kinetics is often
derived from the Hammett linear free energy relationship
[log(kR/kH) = ρσ].22 A Hammett correlation study on meta-
substituted O-methyl oximes exhibited a linear free energy
A further acylation experiment involving 1b and 2b under the
standard conditions was carried out to afford acylated
compound 5a, benzylated compound 5ab, 4-anisaldehyde
F
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relationship (R2 = 0.85) between the relative rate constant (kR/
kH) and the substituent constant (σ) that resulted in a negative
Hammett reaction constant (ρ) value of −0.97 (Figure 2). The
small negative ρ value reveals that the catalyst−substrate
interaction leads to the generation of a partial positive charge
(δ+) on the arene ring, thus indicating a strong support for the
electrophilic palladation mechanism.23 Another possible path-
way, concerted metalation−deprotonation (CMD), may not be
operative in our Pd-catalyzed acylation reaction since this
pathway is based on a positive ρ value in the Hammett
correlation study, leading to a negative charge on the arene
ring.24
On the basis of the above mechanistic investigation, a
plausible reaction mechanism is depicted in Scheme 4. The
oxidative acylation of O-methyl ketoxime 1b is probably
initiated by electrophilic palladation of the arene C−H bond to
form the five-membered cyclopalladated complex I.25 Dibenzyl
ether (2a) is oxidized to give benzylic radicals through C−O
bond cleavage by TBHP in the presence of the Pd catalyst, and
these benzylic radicals can be rapidly converted to reactive
benzoyl radicals.26 The formed palladacycle I can react with a
benzoyl radical to afford dimeric Pd(III) or Pd(IV)
intermediate II,27 which can undergo reductive elimination to
give the desired product 4b and regenerate the Pd(II) catalyst.
= 8.1 Hz, 2H), 7.67 (d, J = 8.2 Hz, 2H), 7.54−7.43 (m, 2H), 7.42 (s,
1H), 3.62 (s, 3H), 2.03 (s, 3H); 13C NMR (175 MHz, CDCl3) δ
194.8, 152.4, 14.6, 139.6, 135.2, 134.3, 130.5, 129.3, 12.8, 127.6, 125.5,
123.5 (q, JC−F = 270.2 Hz), 61.8, 13.7; IR (KBr) υ 2928, 1682, 1589,
1412, 1325, 1271, 1166, 1127, 1067, 902, 856, 826, 776 cm−1; HRMS
(quadrupole, EI) m/z calcd for C17H13ClF3NO2 [M]+ 355.0587, found
355.0579.
(5-Chloro-2-(1-(methoxyimino)ethyl)phenyl)(4-
fluorophenyl)methanone (3d). 69.7 mg (76%); light-yellow solid;
1
mp = 95.3−98.2 °C; H NMR (700 MHz, CDCl3) δ 7.72 (q, J = 3.5
Hz, 2H), 7.49 (q, J = 6.2 Hz, 1H), 7.44 (d, J = 8.3 Hz, 1H), 7.40 (d, J
= 2.2 Hz, 1H), 7.08 (t, J = 8.5 Hz, 2H), 3.63 (s, 3H), 2.02 (s, 3H); 13C
NMR (175 MHz, CDCl3) δ 194.5, 165.5 (d, JC−F = 252.9 Hz), 152.6,
140.1, 134.9, 134.4, 134.0 (d, JC−F = 2.4 Hz), 131.8 (d, JC−F = 9.1 Hz),
130.2, 129.0, 128.7, 115.5 (d, J C−F = 22.2 Hz), 61.8, 14.0; IR (KBr) υ
2936, 1723, 1670, 1599, 1508, 1411, 1364, 1263, 1223, 1153, 1047,
956, 824, 773 cm−1; HRMS (quadrupole, EI) m/z calcd for
+
C16H13ClFNO2 [M] 305.0619, found 305.0613.
(4-Bromophenyl)(5-chloro-2-(1-(methoxyimino)ethyl)-
phenyl)methanone (3e). 60.5 mg (55%); brown solid; mp = 119.8−
127.5 °C; 1H NMR (700 MHz, CDCl3) δ 7.56−7.50 (m, 5H), 7.45 (d,
J = 8.4 Hz, 1H), 7.40 (d, J = 2.1 Hz, 1H), 3.64 (s, 3H), 2.03 (s, 3H);
13C NMR (175 MHz, CDCl3) δ 194.9, 152.5, 139.8, 136.4, 135.0,
134.4, 131.7, 130.6, 130.3, 128.9, 128.8, 127.9, 61.8, 13.9; IR (KBr) υ
2978, 1710, 1591, 1487, 1363, 1266, 1195, 1011, 896, 813, 756 cm−1;
+
HRMS (quadrupole, EI) m/z calcd for C16H13BrClNO2 [M]
364.9818, found 364.9811.
(5-Chloro-2-(1-(methoxyimino)ethyl)phenyl)(m-tolyl)-
methanone (3f). 43.4 mg (48%); colorless oil; 1H NMR (700 MHz,
CDCl3) δ 7.53−7.43 (m, 5H), 7.35−7.28 (m, 2H), 3.67 (s, 3H), 2.37
(s, 3H), 2.00 (s, 3H); 13C NMR (175 MHz, CDCl3) δ 196.2, 153.0,
140.5, 138.2, 137.5, 134.8, 134.7, 133.7, 130.1, 129.7, 129.0, 128.9,
128.3, 126.6, 61.8, 21.3, 14.3; IR (KBr) υ 2934, 1668, 1587, 1456,
1365, 1266, 1103, 1047, 969, 898, 763 cm−1; HRMS (quadrupole, EI)
m/z calcd for C17H16ClNO2 [M]+ 301.0870, found 301.0875.
(5-Chloro-2-(1-(methoxyimino)ethyl)phenyl)(o-tolyl)-
CONCLUSION
■
A directing-group-assisted palladium-catalyzed direct acylation
of arenes using dibenzylic ethers as new acyl equivalents has
been developed. This transformation has been applied to a wide
range of substrates and typically proceeds with excellent levels
of regio- and chemoselectivity as well as with high functional
group tolerance. Further applications of this method to the
synthesis of biologically active compounds are in progress.
1
methanone (3g). 76.0 mg (84%); yellow oil; H NMR (700 MHz,
CDCl3) δ 7.48 (q, J = 5.7 Hz, 2H), 7.38−7.36 (m, 2H), 7.28 (q, J = 0.5
Hz, 1H), 7.20−7.14 (m, 1H), 7.12 (q, J = 7.3 Hz, 1H), 3.77 (s, 3H),
2.57 (s, 3H), 1.92 (s, 3H); 13C NMR (175 MHz, CDCl3) δ 197.5,
154.5, 141.5, 139.5, 137.2, 135.7, 134.7, 131.8, 131.7, 130.6, 130.5,
129.6, 129.5, 125.2, 61.8, 21.3, 15.1; IR (KBr) υ 2933, 1717, 1668,
1600, 1573, 1457, 1364, 1244, 1101, 1047, 941, 894, 822, 750 cm−1;
HRMS (quadrupole, EI) m/z calcd for C17H16ClNO2 [M]+ 301.0870,
found 301.0873.
EXPERIMENTAL SECTION
■
Typical Procedure for the Acylation of Arenes (1a−r) with
Dibenzyl Ethers (2a−i). To an oven-dried sealed tube containing 1-
(4-chlorophenyl)ethanone O-methyl oxime (1a) (55.1 mg, 0.3 mmol,
100 mol %), Pd(OAc)2 (3.4 mg, 0.015 mmol, 5 mol %), and dibenzyl
ether (2a) (178.4 mg, 0.9 mmol, 300 mol %) in DCE (1 mL) were
added TBHP (0.35 mL, 1.8 mmol, 600 mol %, 5.0−6.0 M in decane)
and AcOH (52 μL, 0.9 mmol, 300 mol %). The reaction mixture was
allowed to stir at 80 °C for 6 h, cooled to room temperature, and
evaporated onto silica gel. Purification of the product by flash column
chromatography (SiO2, n-hexanes/EtOAc = 15:1) provided 3a (73.5
mg, 0.255 mmol) in 85% yield.
(5-Chloro-2-(1-(methoxyimino)ethyl)phenyl)(phenyl)-
methanone (3a). 73.3 mg (85%); colorless oil; 1H NMR (700 MHz,
CDCl3) δ 7.70 (dd, J = 8.3, 1.3 Hz, 2H), 7.69−7.40 (m, 6H), 3.64 (s,
3H), 2.00 (s, 3H); 13C NMR (175 MHz, CDCl3) δ 196.0, 152.8,
140.3, 137.6, 134.8, 134.6, 132.9, 130.1, 129.3, 128.9, 128.8, 128.4,
61.8, 14.1; IR (KBr) υ 2936, 1671, 1594, 1479, 1449, 1369, 1315,
1283, 1179, 1105, 1048, 827 cm−1; HRMS (quadrupole, EI) m/z calcd
for C16H14ClNO2 [M]+ 287.0713, found 287.0713.
(5-Chloro-2-(1-(methoxyimino)ethyl)phenyl)(2-
chlorophenyl)methanone (3h). 39.6 mg (41%); white solid; mp =
1
94.3−97.2 °C; H NMR (700 MHz, CDCl3) δ 7.53−7.50 (m, 2H),
7.41 (q, J = 4.3 Hz, 3H), 7.36 (d, J = 8.3 Hz, 1H), 7.30−7.28 (m, 1H),
3.84 (s, 3H), 1.95 (s, 3H); 13C NMR (175 MHz, CDCl3) δ 194.3,
154.6, 140.0, 137.3, 136.0, 134.9, 132.6, 132.4, 131.4, 131.3, 130.9,
130.1, 129.8, 126.5, 62.0, 15.2; IR (KBr) υ 2932, 1682, 1588, 1435,
1317, 1292, 1239, 1102, 1047, 944, 897, 812, 757 cm−1; HRMS
(quadrupole, EI) m/z calcd for C16H13Cl2NO 2 [M]+ 321.0323, found
321.0326.
(5-Chloro-2-(1-(methoxyimino)ethyl)phenyl)(naphthalen-2-
1
yl)methanone (3i). 49.6 mg (49%); yellow sticky solid; H NMR
(700 MHz, CDCl3) δ 8.06−7.84 (m, 5H), 7.63−7.48 (m, 5H), 3.60 (s,
3H), 2.00 (s, 3H); 13C NMR (175 MHz, CDCl3) δ 196.0, 152.9,
140.5, 135.5, 135.0, 134.9, 134.7, 132.4, 131.2, 130.2, 129.5, 129.1,
129.0, 128.5, 128.4, 127.9, 126.8, 124.7, 61.8, 14.2; IR (KBr) υ 2932,
1718, 1669, 1573, 1457, 1364, 1244, 1101, 1047, 941, 894, 822, 752
cm−1; HRMS (quadrupole, EI) m/z calcd for C20H16ClNO2 [M]+
337.0870, found 337.0862.
(2-(1-(Methoxyimino)ethyl)phenyl)(phenyl)methanone (4b).
53.9 mg (71%); light-yellow solid; mp = 93.5−99.2 °C; 1H NMR (700
MHz, CDCl3) δ 7.71 (dd, J = 8.3, 1.3 Hz, 2H), 7.54−7.44 (m, 5H),
7.39 (t, J = 8.2 Hz, 2H), 3.67 (s, 3H), 2.02 (s, 3H); 13C NMR (175
MHz, CDCl3) δ 197.6, 154.0, 138.9, 138.2, 136.4, 132.6, 130.2, 129.3,
129.0, 128.6, 128.3, 127.7, 61.7, 14.4; IR (KBr) υ 2935, 1668, 1597,
(5-Chloro-2-(1-(methoxyimino)ethyl)phenyl)(4-
methoxyphenyl)methanone (3b). 64.8 mg (68%); colorless sticky
1
solid; H NMR (700 MHz, CDCl3) δ 7.69 (dd, J = 6.9, 2.1 Hz, 2H),
7.47−7.39 (m, 3H), 6.89 (dd, J = 6.9, 2.1 Hz, 2H), 3.86 (s, 3H), 3.67
(s, 3H), 2.02 (s, 3H); 13C NMR (175 MHz, CDCl3) δ 194.8, 163.5,
153.1, 140.7, 134.7, 134.6, 131.8, 130.4, 129.8, 129.1, 128.7, 113.7,
61.8, 55.5, 14.4; IR (KBr) υ 2934, 1601, 1510, 1457, 1315, 1254, 1174,
1046, 946, 898, 818, 774 cm−1; HRMS (quadrupole, EI) m/z calcd for
C17H16ClNO3 [M]+ 317.0819, found 317.0815.
(5-Chloro-2-(1-(methoxyimino)ethyl)phenyl)(4-
(trifluoromethyl)phenyl)methanone (3c). 62.9 mg (59%); yellow
solid; mp = 106.5−110.6 °C; 1H NMR (700 MHz, CDCl3) δ 7.79 (d, J
G
dx.doi.org/10.1021/jo4024304 | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
1449, 1367, 1313, 1286, 1154, 1048, 928 cm−1; HRMS (quadrupole,
EI) m/z calcd for C16H15NO2 [M] 253.1103, found 253.1102.
(d, JC−F = 2.1 Hz), 138.2, 137.7 (d, JC−F = 4.3 Hz), 133.2, 130.9 (d,
JC−F = 8.9 Hz), 129.8, 128.6, 126.9 (d, JC−F = 19.2 Hz), 123.5 (d, JC−F
= 2.8 Hz), 116.4 (d, JC−F = 21.5 Hz), 61.9, 13.8; IR (KBr) υ 2934,
1730, 1667, 1580, 1465, 1364, 1265, 1204, 1051, 945 cm−1; HRMS
(quadrupole, EI) m/z calcd for C16H14FNO2 [M]+ 271.1009, found
271.1010.
+
(5-Methoxy-2-(1-(methoxyimino)ethyl)phenyl)(phenyl)-
methanone (4c). 54.4 mg (64%); colorless oil; 1H NMR (700 MHz,
CDCl3) δ 7.70 (dd, J = 8.3, 1.2 Hz, 2H), 7.50 (t, J = 7.3 Hz, 1H), 7.41
(d, J = 8.6 Hz, 1H), 7.38 (t, J = 8.2 Hz, 2H), 7.04 (dd, J = 8.6, 2.6 Hz,
1H), 6.98 (d, J = 2.7 Hz, 1H), 3.83 (s, 3H), 3.62 (s, 3H), 1.98 (s, 3H);
13C NMR (175 MHz, CDCl3) δ 197.3, 159.8, 153.3, 140.3, 138.1,
132.5, 129.2, 128.9, 128.6, 128.2, 115.9, 114.0, 61.5, 55.6, 14.2; IR
(KBr) υ 2937, 1669, 1601, 1497, 1414, 1367, 1288, 1177, 1122, 1040,
896 cm−1; HRMS (quadrupole, EI) m/z calcd for C17H17NO3 [M]+
283.1208, found 283.1212.
(5-Fluoro-2-(1-(methoxyimino)ethyl)phenyl)(phenyl)-
methanone (4d). 56.9 mg (70%); yellow solid; mp = 94.6−98.2 °C;
1H NMR (700 MHz, CDCl3) δ 7.63 (dd, J = 8.3, 1.2 Hz, 2H), 7.46 (t,
J = 7.4 Hz, 1H), 7.42−7.40 (m, 1H), 7.34 (t, J = 8.2 Hz, 2H), 7.16−
7.13 (m, 1H), 7.11 (dd, J = 8.4, 2.6 Hz, 1H), 3.58 (s, 3H), 1.94 (s,
3H); 13C NMR (175 MHz, CDCl3) δ 196.0, 162.5 (d, JC−F = 247.4
Hz), 152.9, 140.9 (d, JC−F = 6.4 Hz), 137.6, 132.9, 130.3, 129.6 (d, J
(3-(1-(Methoxyimino)ethyl)naphthalen-2-yl)(phenyl)-
methanone (4i). 61.8 mg (68%); yellow solid; mp = 147.3−154.8
°C; 1H NMR (700 MHz, CDCl3) δ 7.98 (s, 1H), 7.94 (s, 1H), 7.91 (d,
J = 7.9 Hz, 1H), 7.87 (d, J = 8.0 Hz, 1H), 7.76 (dd, J = 8.2, 1.2 Hz,
2H), 7.60−7.52 (m, 3H), 7.41 (t, J = 7.9 Hz, 2H), 3.71 (s, 3H), 2.15
(s, 3H); 13C NMR (175 MHz, CDCl3) δ 197.3, 153.8, 138.4, 136.6,
133.6, 132.5, 132.4, 129.5, 129.4, 128.5, 128.3, 128.2, 127.9, 127.6,
127.4, 61.7, 14.2; IR (KBr) υ 2935, 1742, 1681, 1597, 1451, 1365,
1282, 1193, 1053, 872 cm−1; HRMS (quadrupole, EI) m/z calcd for
+
C20H17NO2 [M] 303.1259, found 303.1261.
(4-(Methoxyimino)chroman-5-yl)(phenyl)methanone (4j).
1
61.6 mg (73%); white solid; mp = 103.9−105.9 °C; H NMR (700
MHz, CDCl3) δ 7.75 (dd, J = 8.2, 1.2 Hz, 1H), 7.49 (t, J = 7.3 Hz,
1H), 7.38 (t, J = 8.9 Hz, 2H), 7.33 (t, J = 7.7 Hz, 1H), 7.01 (dd, J =
8.3, 1.2 Hz, 1H), 6.89 (dd, J = 7.3, 1.1 Hz, 1H), 4.22 (t, J = 6.2 Hz,
2H), 3.51 (s, 3H), 2.79 (t, J = 6.2 Hz, 2H); 13C NMR (175 MHz,
CDCl3) δ 197.3, 156.9, 146.0, 138.9, 137.9, 132.4, 130.4, 129.0, 128.2,
120.9, 118.8, 116.2, 64.9, 61.7, 24.0; IR (KBr) υ 2937, 1673, 1595,
1469, 1318, 1279, 1145, 1079, 945, 850 cm−1; HRMS (quadrupole,
C−F = 7.5 Hz), 129.3, 128.4, 117.0 (d, JC−F = 21.6 Hz), 116.2 (d, JC−F
=
24.0 Hz), 61.7, 14.3; IR (KBr) υ 2937, 1671, 1600, 1578, 1492, 1408,
1369, 1318, 1274, 1178, 1070, 976, 828 cm−1; HRMS (quadrupole,
+
EI) m/z calcd for C16H14FNO2 [M] 271.1009, found 271.1009.
(2-(1-(Methoxyimino)ethyl)-5-(trifluoromethyl)phenyl)-
(phenyl)methanone (4e). 44.3 mg (46%); yellow oil; 1H NMR (700
MHz, CDCl3) δ 7.78 (d, J = 8.1 Hz, 1H), 7.71−7.67 (m, 3H), 7.63 (d,
J = 8.1 Hz, 1H), 7.55 (t, J = 7.4 Hz, 1H), 7.42 (t, J = 8.2 Hz, 2H), 3.66
(s, 3H), 2.05 (s, 3H); 13C NMR (175 MHz, CDCl3) δ 196.1, 152.7,
139.6, 139.5, 137.4, 133.0, 130.7 (q, JC−F = 32.9 Hz), 129.3, 128.5,
128.1, 126.8 (q, JC−F = 3.0 Hz), 125.8 (q, JC−F = 3.0 Hz), 123.6 (q,
JC−F = 270.8 Hz), 62.0, 14.1; IR (KBr) υ 2939, 1673, 1450, 1339, 1269,
1175, 1130, 1092, 1048, 840 cm−1; HRMS (quadrupole, EI) m/z calcd
for C17H14F3NO2 [M]+ 321.0977, found 321.0972.
(4-Methoxy-2-(1-(methoxyimino)ethyl)phenyl)(phenyl)-
methanone (4f). 39.0 mg (46%); colorless oil; 1H NMR (700 MHz,
CDCl3) δ 7.67 (dd, J = 8.2, 1.2 Hz, 2H), 7.49 (t, J = 7.4 Hz, 1H), 7.46
(d, J = 8.4 Hz, 1H), 7.38 (t, J = 8.1 Hz, 2H), 6.95 (d, J = 2.5 Hz, 2H),
6.93 (dd, J = 8.4, 2.5 Hz, 1H), 3.87 (s, 3H), 3.71 (s, 3H), 1.97 (s, 3H);
13C NMR (175 MHz, CDCl3) δ 197.1, 161.5, 155.0, 139.5, 138.9,
+
EI) m/z calcd for C17H15NO3 [M] 281.1052, found 281.1049.
(E)-2-Benzoyl-6-chlorobenzaldehyde O-Methyl Oxime (4k).
1
23.0 mg (28%); colorless oil; H NMR (700 MHz, CDCl3) δ 8.29 (s,
1H), 7.70 (q, J = 7.1 Hz, 2H), 7.54−7.53 (m, 2H), 7.43−7.40 (m,
3H), 7.31−7.30 (m, 1H), 3.60 (s, 3H); 13C NMR (175 MHz, CDCl3)
δ 196.3, 143.8, 141.0, 137.4, 134.4, 132.9, 131.1, 130.2, 129.3, 128.4,
128.1, 127.0, 62.1; IR (KBr) υ 2936, 1674, 1597, 1448, 1314, 1280,
1136, 1048, 964, 804, 710 cm−1; HRMS (quadrupole, EI) m/z calcd
for C15H12ClNO2 [M]+ 273.0557, found 273.0555.
(2-((Methoxyimino)(phenyl)methyl)phenyl)(phenyl)-
methanone (4l). 68.1 mg (72%); white solid; mp = 91.5−98.0 °C;
1H NMR (700 MHz, CDCl3) δ 7.72 (dd, J = 8.2, 1.2 Hz, 2H), 7.50−
7.44 (m, 4H), 7.38 (t, J = 8.2 Hz, 2H), 7.31−7.27 (m, 6H), 3.69 (s,
3H); 13C NMR (175 MHz, CDCl3) δ 197.5, 154.8, 140.0, 138.0,
135.9, 132.7, 132.6, 130.2, 129.8, 129.6, 129.4, 129.2, 129.0, 128.9,
128.2, 128.0, 62.2; IR (KBr) υ 2935, 2897, 2816, 1590, 1484, 1444,
1326, 1165, 1054, 1031, 982, 919, 878 cm−1; HRMS (quadrupole, EI)
132.5, 131.9, 131.3, 129.6, 128.4, 114.2, 113.6, 61.9, 55.8, 15.4; IR
(KBr) υ 2961, 2936, 1767, 1659, 1597, 1420, 1366, 1177, 1140, 1065,
1040, 1001, 928 cm−1; HRMS (quadrupole, EI) m/z calcd for
C17H17NO3 [M]+ 283.1208, found 283.1210.
+
m/z calcd for C21H17NO2 [M] 315.1259, found 315.1257.
(2-((Methoxyimino)(m-tolyl)methyl)phenyl)(phenyl)-
methanone (4m) and (2-((Methoxyimino)(phenyl)methyl)-4-
methylphenyl)(phenyl)methanone (4m′). 71.1 mg (72%); color-
less oil; 1H NMR (700 MHz, CDCl3) δ 7.72 (dd, J = 8.3, 1.2 Hz, 2H),
7.69 (dd, J = 8.3, 1.2 Hz, 2H), 7.48−7.43 (m, 5H), 7.39−7.32 (m,
5H), 7.29−7.26 (m, 7H), 7.19 (t, J = 7.6 Hz, 1H), 7.12 (br s, 1H),
7.10 (d, J = 8.2 Hz, 1H), 7.06 (d, J = 7.6 Hz, 2H), 7.03 (br s, 1H), 3.17
(s, 3H), 3.68 (s, 3H), 2.37 (s, 3H), 2.28 (s, 3H); 13C NMR (175 MHz,
CDCl3) δ 197.6, 197.5, 155.3, 155.1, 140.5, 140.1, 138.3, 137.7, 137.4,
136.4, 136.1, 132.9, 132.8, 132.7, 132.6, 130.9, 130.2, 130.1, 129.9,
129.8, 129.7, 129.6, 129.5, 129.4, 129.3, 129.0, 128.3, 128.2, 128.0,
126.8, 62.3, 21.6, 21.5; IR (KBr) υ 2859, 1665, 1630, 1597, 1491,
1447, 1314, 1285, 1150, 1049, 988, 926 cm−1; HRMS (quadrupole,
EI) m/z calcd for C22H19NO2 [M]+ 329.1416, found 329.1419.
(Phenyl)(2-(pyridin-2-yl)phenyl)methanone (4n). 56.7 mg
(73%); light-yellow solid; mp = 104.9−108.4 °C; 1H NMR (700
MHz, CDCl3) δ 8.27 (d, J = 4.8 Hz, 1H), 7.69 (d, J = 7.7 Hz, 1H),
7.60 (dd, J = 8.3, 2.8 Hz, 2H), 7.53−7.50 (m, 1H), 7.48−7.40 (m,
4H), 7.29 (t, J = 7.3 Hz, 1H), 7.18 (t, J = 7.4 Hz, 2H), 6.91 (ddd, J =
7.4, 4.8, 1.1 Hz, 1H); 13C NMR (175 MHz, CDCl3) δ 198.3, 156.8,
149.1, 139.7, 139.5, 137.9, 136.3, 132.4, 130.2, 129.4, 129.1, 128.8,
128.5, 128.1, 122.7, 122.0; IR (KBr) υ 2923, 1665, 1586, 1448, 1426,
1313, 1280, 1151, 1023, 928, 755 cm−1; HRMS (quadrupole, EI) m/z
calcd for C18H13NO [M]+ 259.0997, found 259.0999.
(2-(1-(Methoxyimino)ethyl)-4-methylphenyl)(phenyl)-
methanone (4g). 51.3 mg (64%); light-yellow solid; mp = 94.9−99.7
1
°C; H NMR (700 MHz, CDCl3) δ 7.68 (dd, J = 8.3, 1.3 Hz, 2H),
7.94 (t, J = 7.4 Hz, 1H), 7.38−7.36 (m, 3H), 7.27 (br s, 1H), 7.25−
7.23 (m, 1H), 3.68 (s, 3H), 2.42 (s, 3H), 1.98 (s, 3H); 13C NMR (175
MHz, CDCl3) δ 197.8, 154.7, 140.9, 138.6, 137.0, 136.2, 132.6, 129.6,
129.5, 129.4, 128.7, 61.8, 21.7, 15.0; IR (KBr) υ 2935, 1732, 1663,
1597, 1447, 1365, 1254, 1179, 1071, 918 cm−1; HRMS (quadrupole,
+
EI) m/z calcd for C17H17NO2 [M] 267.1259, found 267.1257.
(4-Fluoro-2-(1-(methoxyimino)ethyl)phenyl)(phenyl)-
methanone (4h). 39.0 mg (48%); white solid; mp = 142.5−148.8
1
°C; H NMR (700 MHz, CDCl3) δ 7.67 (dd, J = 8.3, 1.2 Hz, 2H),
7.50 (t, J = 7.4 Hz, 1H), 7.46 (dd, J = 8.5, 5.7 Hz, 1H), 7.39 (t, J = 7.8
Hz, 2H), 7.17 (dd, J = 9.6, 2.5 Hz, 1H), 7.13 (dt, J = 8.3, 2.6 Hz, 1H),
3.67 (s, 3H), 1.98 (s, 3H); 13C NMR (175 MHz, CDCl3) δ 196.7,
163.7 (d, JC−F = 249.6 Hz), 153.3, 139.3 (d, JC−F = 7.5 Hz), 138.3,
135.1 (d, JC−F = 2.9 Hz), 132.9, 131.5 (d, JC−F = 8.9 Hz), 129.5, 128.5,
11.6 (d, JC−F = 21.8 Hz), 115.1 (d, JC−F = 22.6 Hz), 62.0, 14.6; IR
(KBr) υ 2934, 1728, 1667, 1580, 1464, 1364, 1265, 1204, 1049, 945
+
cm−1; HRMS (quadrupole, EI) m/z calcd for C16H14FNO2 [M]
271.1009, found 271.1012.
(2-Fluoro-6-(1-(methoxyimino)ethyl)phenyl)(phenyl)-
methanone (4h′). 19.5 mg (24%); colorless oil; 1H NMR (700
MHz, CDCl3) δ 7.78 (dd, J = 7.9, 0.7 Hz, 2H), 7.52 (t, J = 7.3 Hz,
1H), 7.46−7.43 (m, 1H), 7.41 (t, J = 7.8 Hz, 2H), 7.29 (dd, J = 7.8, 0.7
Hz, 1H), 7.14 (t, J = 8.9 Hz, 1H), 3.54 (s, 3H), 2.06 (s, 3H); 13C
NMR (175 MHz, CDCl3) δ 193.4, 159.9 (d, JC−F = 246.8 Hz), 152.8
(Benzo[h]quinolin-10-yl)(phenyl)methanone (4o). 59.4 mg
(70%); light-brown solid; mp = 145.5−148.3 °C; 1H NMR (700
MHz, CDCl3) δ 8.52 (d, J = 4.3 Hz, 1H), 8.10 (dd, J = 7.9, 1.7 Hz,
H
dx.doi.org/10.1021/jo4024304 | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
1H), 8.06 (dd, J = 7.9, 1.0 Hz, 1H), 7.91 (d, J = 8.7 Hz, 1H), 7.81−
7.79 (m, 3H), 7.75 (d, J = 8.8 Hz, 1H), 7.65 (d, J = 7.1 Hz, 1H), 7.43
(t, J = 7.3 Hz, 1H), 7.34−7.31 (m, 3H); 13C NMR (175 MHz, CDCl3)
δ 198.7, 147.1, 144.7, 139.3, 139.0, 135.3, 133.8, 131.8, 129.2, 129.0,
128.7, 128.1, 127.9, 127.8, 127.0, 126.4, 126.2, 121.7; IR (KBr) υ 2924,
1668, 1511, 1422, 1314, 1273, 1175, 1005, 914, 892, 837, 730 cm−1;
HRMS (quadrupole, EI) m/z calcd for C20H13NO [M]+ 283.0997,
found 283.0995.
(2-(1H-Pyrazol-1-yl)phenyl)(phenyl)methanone (4p). 41.7 mg
(56%); white solid; mp = 84.1−87.3 °C; 1H NMR (700 MHz, CDCl3)
δ 7.64−7.56 (m, 6H), 7.48−7.46 (m, 1H), 7.49−7.38 (m, 2H), 7.28 (t,
J = 7.4 Hz, 2H), 6.16 (t, J = 2.1 Hz, 1H); 13C NMR (175 MHz,
CDCl3) δ 195.9, 141.2, 138.6, 136.8, 133.8, 132.9, 131.3, 129.8, 129.6,
129.1, 128.2, 127.5, 123.3, 107.7; IR (KBr) υ 2923, 1668, 1602, 1519,
1450, 1393, 1274, 1151, 1046, 936, 800, 752 cm−1; HRMS
(quadrupole, EI) m/z calcd for C16H12N2O [M]+ 248.0950, found
248.0948.
(3-Fluoro-2-(pyridin-2-yloxy)phenyl)(phenyl)methanone
(4q). 43.1 mg (49%); yellow sticky solid; 1H NMR (700 MHz,
CDCl3) δ 8.01 (d, J = 4.9 Hz, 1H), 7.76 (dd, J = 8.4, 1.2 Hz, 2H),
7.54−7.51 (m, 1H), 7.47 (t, J = 7.4 Hz, 1H), 7.37−7.29 (m, 5H), 6.89
(ddd, J = 7.1, 4.9, 0.9 Hz, 1H), 6.68 (d, J = 8.2 Hz, 1H); 13C NMR
(175 MHz, CDCl3) δ 194.1, 162.3, 154.7 (d, JC−F = 249.7 Hz), 146.9,
139.2 (d, JC−F = 27.0 Hz), 139.1, 137.1, 135.0, 133.1, 129.9, 128.1,
(4) For selected examples of C−H acylation using aldehydes, see:
(a) Jia, X.; Zhang, S.; Wang, W.; Luo, F.; Cheng, J. Org. Lett. 2009, 11,
3120. (b) Park, J.; Park, E.; Kim, A.; Lee, Y.; Chi, K.-W.; Kwak, J. H.;
Jung, Y. H.; Kim, I. S. Org. Lett. 2011, 13, 4390. (c) Sharma, S.; Park,
E.; Park, J.; Kim, I. S. Org. Lett. 2012, 14, 906. (d) Sharma, S.; Park, J.;
Park, E.; Kim, A.; Kim, M.; Kwak, J. H.; Jung, Y. H.; Kim, I. S. Adv.
Synth. Catal. 2013, 355, 332. (e) Chan, C.-W.; Zhou, Z.; Chan, A. S.
C.; Yu, W.-Y. Org. Lett. 2010, 12, 3926. (f) Yang, Y.; Zhou, B.; Li, Y.
Adv. Synth. Catal. 2012, 354, 2916. (g) Sharma, S.; Kim, A.; Park, J.;
Kim, M.; Kwak, J. H.; Jung, Y. H.; Park, J. S.; Kim, I. S. Org. Biomol.
Chem. 2013, 11, 7869.
(5) For selected examples of C−H acylation using alcohols, see:
(a) Xiao, F.; Shuai, Q.; Zhao, F.; Basle, O.; Deng, G.; Li, C.-J. Org. Lett.
́
2011, 13, 1614. (b) Park, J.; Kim, A.; Sharma, S.; Kim, M.; Park, E.;
Jeon, Y.; Lee, Y.; Kwak, J. H.; Jung, Y. H.; Kim, I. S. Org. Biomol. Chem.
2013, 11, 2766. (c) Kim, M.; Sharma, S.; Park, J.; Kim, M.; Choi, Y.;
Jeon, Y.; Kwak, J. H.; Kim, I. S. Tetrahedron 2013, 69, 6552.
(d) Sharma, S.; Kim, M.; Park, J.; Kim, M.; Kwak, J. H.; Jung, Y. H.;
Oh, J. S.; Lee, Y.; Kim, I. S. Eur. J. Org. Chem. 2013, 6656.
(6) For selected examples of C−H acylation using α-oxocarboxylic
acids, see: (a) Fang, P.; Li, M.; Ge, H. J. Am. Chem. Soc. 2010, 132,
11898. (b) Li, M.; Ge, H. Org. Lett. 2010, 12, 3464. (c) Wang, H.;
Guo, L.-N.; Duan, X.-H. Org. Lett. 2012, 14, 4358. (d) Kim, M.; Park,
J.; Sharma, S.; Kim, A.; Park, E.; Kwak, J. H.; Jung, Y. H.; Kim, I. S.
Chem. Commun. 2013, 49, 925. (e) Park, J.; Kim, M.; Sharma, S.; Park,
E.; Kim, A.; Lee, S. H.; Kwak, J. H.; Jung, Y. H.; Kim, I. S. Chem.
Commun. 2013, 49, 1654. (f) Sharma, S.; Kim, A.; Park, E.; Park, J.;
Kim, M.; Kwak, J. H.; Lee, S. H.; Jung, Y. H.; Kim, I. S. Adv. Synth.
Catal. 2013, 355, 667. (g) Yu, L.; Li, P.; Wang, L. Chem. Commun.
2013, 49, 2368. (h) Li, H.; Li, P.; Zhao, Q.; Wang, L. Chem. Commun.
2013, 49, 9170. (i) Miao, J.; Ge, H. Org. Lett. 2013, 15, 2930.
(7) (a) Guin, S.; Rout, S. K.; Banerjee, A.; Nandi, S.; Patel, B. K. Org.
Lett. 2012, 14, 5294. (b) Wu, Y.; Choy, P. Y.; Mao, F.; Kwong, F. Y.
Chem. Commun. 2013, 49, 689.
125.7 (d, JC−F = 7.4 Hz), 125.0 (d, JC−F = 4.1 Hz), 119.0 (d, JC−F
=
19.3 Hz), 118.7, 110.7; IR (KBr) υ 2939, 2830, 1669, 1597, 1463,
1429, 1271, 1190, 1143, 1068, 887, 777 cm−1; HRMS (quadrupole,
EI) m/z calcd for C18H12FNO2 [M]+ 293.0852, found 293.0851.
ASSOCIATED CONTENT
* Supporting Information
■
S
Spectroscopic data for all compounds. This material is available
free of charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
(8) Zhou, W.; Li, H.; Wang, L. Org. Lett. 2012, 14, 4594.
(9) Lu, J.; Zhang, H.; Chen, X.; Liu, H.; Jiang, Y.; Fu, H. Adv. Synth.
Catal. 2013, 355, 529.
(10) Zhang, Q.; Yang, F.; Wu, Y. Chem. Commun. 2013, 49, 6837.
(11) Wuts, P. G. M.; Green, T. W. Protective Groups in Organic
Synthesis, 4th ed.; Wiley & Sons: New York, 2007; pp 102−120.
(12) Markees, D. G. J. Org. Chem. 1958, 23, 1490.
■
*Tel.: +82-31-290-7788. Fax: +82-31-292-8800. E-mail:
insukim@skku.edu.
Notes
The authors declare no competing financial interest.
(13) Mayhoub, A. S.; Talukdar, A.; Cushman, M. J. Org. Chem. 2010,
75, 3507.
ACKNOWLEDGMENTS
■
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This research was supported by the Basic Science Research
Program through the National Research Foundation of Korea
(NRF) funded by the Ministry of Education, Science and
Technology (2013R1A2A2A01005249).
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