Easy-to-execute carbonylative arylation of aryl halides using molybdenum hexacarbonyl: Efficient synthesis of unsymmetrical diaryl ketones

Article abstract of DOI:10.1002/ejoc.201001733

A versatile procedure for the synthesis of unsymmetrical diaryl ketones through a palladium-catalyzed carbonylative arylation of iodoarenes through easy-to-handle molybdenum hexacarbonyl as a condensed source of carbon monoxide is described. This method provides an efficient route to a wide variety of substituted diaryl ketones without direct use of high-pressure carbon monoxide. Copyright

Full text of DOI:10.1002/ejoc.201001733

FULL PAPER
DOI: 10.1002/ejoc.201001733
Easy-to-Execute Carbonylative Arylation of Aryl Halides using Molybdenum
Hexacarbonyl: Efficient Synthesis of Unsymmetrical Diaryl Ketones
Farnaz Jafarpour,*[a] Parviz. Rashidi-Ranjbar,[a] and Asieh Otaredi Kashani[a]
Keywords: Carbonylation / Ketones / Molybdenum / Palladium / Cross-coupling
A versatile procedure for the synthesis of unsymmetrical di-
aryl ketones through a palladium-catalyzed carbonylative
arylation of iodoarenes through easy-to-handle molybdenum
hexacarbonyl as a condensed source of carbon monoxide is
described. This method provides an efficient route to a wide
variety of substituted diaryl ketones without direct use of
high-pressure carbon monoxide.
particularly convenient in recent years. Some examples in-
clude palladium-catalyzed cross-coupling of boronic acids
with carboxylic acids or anhydrides[10] and direct synthesis
of aryl ketones from carbonylative Suzuki cross-coupling of
arylboronic acids and aryl halides, triflates, and aryldiazon-
ium salts in the presence of gaseous carbon monoxide.[11]
However, in this approach the selectivity of coupling is the
major issue. The major products of this reaction are sym-
metrical biaryls without insertion of carbon monoxide. In
this regard, catalytic systems including PdCl2(PPh3)2/
PdCl2(dppf),[12] imidazolium-based Pd catalysts,[13] Pd/thio-
urea catalyst with a phosphane-free ligand,[14] Pd/diada-
Introduction
Diaryl ketones have received increasing attention because
of their occurrence in natural products,[1] several biological
and pharmacological activities,[2] and uses as photoinitia-
tors in UV-curing applications like inks, imaging, and clear
coatings in the printing industry. For instance, benzophe-
none derivatives I and II, which have been isolated from
the stems of Garcinia multiflora[3] and Vismia cayennensis,[4]
respectively, are known to exhibit cytotoxic, antioxidative,
and antiviral activities (Scheme 1). Furthermore, benzophe-
nones such as dioxybenzone, oxybenzone, and sulisoben-
zone have been reported as active ingredients in sun-
screens.[5] The typical procedure for the synthesis of diaryl
ketones, that is, Friedel–Crafts acylation, yields these prod-
ucts mostly as isomeric mixtures and requires more than
stoichiometric amounts of Lewis acids.[6] Other synthetic
strategies include the reaction of activated carboxylic acid
derivatives with Grignard[7] and organotin compounds[8]
and nickel-catalyzed cross-coupling reactions of aromatic
aldehydes with aryl iodides.[9]
mantyl-n-butylphosphane
(cataCXium A)
system,[15]
PEPPSI–IPr catalyst,[16] and MCM-41-supported bidentate
phosphane palladium(II) complex (MCM-41-2P-PdII)[17]
have been developed to address this issue. However, most
of these methods require additional halide salts, highly ef-
ficient N/P-containing ligands, and elevated pressures of
gaseous carbon monoxide. Very recently, a phosphane-free
Pd(tmhd)2/Pd(OAc)2 complex was also reported to promote
only the Suzuki carbonylation of aryl and heteroaryl io-
dides under elevated pressures of CO.[18] The application of
gaseous CO at higher pressures has suppressed the forma-
tion of biaryl side products; however, carbonylation pro-
cesses employing in situ generation of carbon monoxide
would be more appealing, as it seems suitable for high-
throughput organic synthesis. Innovative inventions have
been recently reported to develop reagents that can be used
as a substitute for gaseous carbon monoxide.[19] In this re-
gard, some organic carbonyl compounds such as formates,
formamides, formic acid, formic anhydride, chloroform,
and aldehydes, as well as metal carbonyls, were introduced.
As the incorporation of the carbon monoxide from a metal
carbonyl is more favorable than an organic carbonyl com-
pound, we preliminary focused on carbonylative procedures
in which metal carbonyls were used. In this regard, molyb-
denum hexacarbonyl was previously identified as an easily
Scheme 1. Diaryl ketone derivatives with biological activities.
Because boronic acids are readily available, nontoxic, and
air- and moisture-stable sources of carbon nucleophiles,
their use in the preparation of diaryl ketones has become
[a] School of Chemistry, College of Science, University of Tehran,
14155-6455 Tehran, Iran
Fax: +98-21-66495291
E-mail: jafarpur@khayam.ut.ac.ir
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Efficient Synthesis of Unsymmetrical Diaryl Ketones
handled solid reagent for the in situ release of carbon mon-
While inferior results were obtained with bases like
oxide upon heating in sealed vessels. It has been proven to K2HPO4, Cs2CO3, tBuOK, and KOAc; K2CO3 proved the
enable the fast development of new easy-to-execute carbon- most promising (Table 1, Entry 5). Replacement of anisole
ylation protocols and depending on the nucleophiles em- with other solvents like DMF, THF, and toluene afforded
ployed, aromatic esters,[20] amides,[21] carboxylic acids,[20,21a] the desired diaryl ketone in very low yields and led to the
sulfonimides,[22] and alkynyl ketones[23] were smoothly ob-
tained. Furthermore, it has also been employed in double
carbonylation of aryl iodides in the presence of tBu3P as
Table 2. Scope of carbonylative Suzuki coupling using Mo(CO)6 as
CO source.
a ligand.[24] Although these carbonylation reactions in the
presence of various nucleophiles were successful, to the best
of our knowledge, direct synthesis of unsymmetrical diaryl
ketones from carbonylative coupling of arylboronic acids
and aryl halides using a solid carbon monoxide source have
not been reported. As part of our continuing efforts in pal-
ladium-catalyzed C–C bond-forming reactions,[25] herein we
set out to explore the methodology to construct diaryl
ketone scaffolds through three-component cross-coupling
of aryl and heteroaryl halides, Mo(CO)6 as a solid carbon
monoxide source, and boronic acids. This protocol takes
advantage of the microwave-free release of carbon mon-
oxide from a metal carbonyl under mild reaction conditions
and the chemoselectivity for the cross-coupling reaction
along with CO insertion without external carbon monoxide
gas.
Results and Discussion
To test the feasibility of the reaction, the carbonylative
cross-coupling of iodotoluene (1a) with phenylboronic acid
(2a) was initially examined in the presence of DBU to accel-
erate the release of carbon monoxide from the metal car-
bonyl Mo(CO)6. However, only 15% of desired product 3a
was obtained (Table 1, Entry 1). A screening of bases was
then performed (Table 1, Entries 2–8).
Table 1. Screening of the reaction conditions for construction of
diaryl ketone 3a.[a]
Entry
Base
Solvent (m)
T
[°C]
Time
[h]
Yield
[%][b]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
DBU
anisole (0.1)
160
160
160
160
160
160
160
160
160
160
160
160
160
140
140
24
24
24
24
24
24
24
24
24
24
24
24
24
12
8
15
10
9
20
60
55
10
38
8
21
12
79
58
K2HPO4 anisole (0.1)
KH2PO4 anisole (0.1)
Cs2CO3 anisole (0.1)
K2CO3
py
tBuOK
KOAc
K2CO3
K2CO3
K2CO3
K2CO3
anisole (0.1)
anisole (0.1)
anisole (0.1)
anisole (0.1)
DMF (0.1)
THF (0.1)
toluene (0.1)
anisole (0.2)
K2CO3 anisole (0.05)
K2CO3
K2CO3
anisole (0.2)
anisole (0.2)
81 (78)[c]
68
[a] Reaction conditions: phenylboronic acid (2.5 equiv.), Pd(OAc)2
(10 mol-%), Mo(CO)6 (1.5 equiv.), and K2CO3 (3 equiv.) were
heated in a sealed tube. [b] GC yield. [c] Isolated yield in parenthe-
ses.
[a] Reaction conditions: A mixture of phenylboronic acid
(2.5 equiv.), Pd(OAc)2 (10 mol-%), Mo(CO)6 (1.5 equiv.), and
K2CO3 (3 equiv.) in anisole (0.2 m) was heated in a sealed tube at
140 °C for 12 h.
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F. Jafarpour, P. Rashidi-Ranjbar, A. O. Kashani
FULL PAPER
desired products in moderate to good yields (Table 2, En-
tries 10–12). N-Methylsulfonyl-substituted aryl iodide 1m
afforded desired product 3m in good yield as well (Table 2,
Entry 13).
Furthermore, we studied the scope and limitations of the
carbonylative Suzuki–Miyaura cross-coupling reaction with
other arylboronic acids (Table 3). The carbonylative cross-
coupling reaction of methyl- and chloro-substituted aryl-
Scheme 2. Carbonylative coupling of iodoarenes and phenylbo-
ronic acid.
formation of the biaryl product as the major one (Table 1, boronic acids and iodoarenes also proceeded smoothly un-
Entries 9–11). The experiments exposed K2CO3/anisole to der the same optimized reaction conditions to give the cor-
be the best base/solvent combination. Further optimiza- responding unsymmetrical diaryl ketones in high yields
tions revealed that reducing the amount of solvent in- (Table 3, Entries 1–4). It was also desirable to expand the
creased the yield of 3a (Table 1, Entries 5, 12, 13). The effect scope of the method for providing aryl heteroaryl ketones.
of temperature was evaluated, and 140 °C gave the best re- In this regard, 3-iodopyridine and 2-iodothiophene were
sult. Further lowering of the temperature decreased the treated with substituted arylboronic acids 2c and 2e and
yield of the desired product, most likely due to inefficient gratifyingly the desired products were obtained in 85 and
liberation of carbon monoxide. Finally, shortening the reac- 76% yield, respectively (Table 3, Entries 5 and 6).
tion time to 12 h was not accompanied with a considerable
Table 3. Scope of carbonylative Suzuki coupling reaction of iodoar-
enes with various arylboronic acids.
decrease in the product yield (Table 1, Entry 14). Under the
optimized reaction conditions, iodoarene 1a (0.2 mmol,
1 equiv.), phenylboronic acid (2a; 0.5 mmol, 2.5 equiv.),
Pd(OAc)2 (10 mol-%), Mo(CO)6 (0.3 mmol, 1.5 equiv.), and
K2CO3 (0.6 mmol, 3 equiv.) in anisole (0.2 m) at 140 °C in
a sealed tube for 12 h afforded diaryl ketone 3a in 78%
yield (Table 2, Entry 1). Encouraged by this result, the
scope of the reaction with a range of aryl iodides was ex-
plored. Various iodoarenes bearing electron-donating and
electron-withdrawing groups were used and diaryl ketones
were obtained in high to excellent yields (Scheme 2,
Table 2). Iodobenzene gave benzophenone in 86% yield
(Table 2, Entry 2). Employment of para-methyl-substituted
1c led to even superior results, producing diaryl ketone 3c
in 90% yield (Table 2, Entry 3). Dimethyl-substituted 1d
also gave comparable result (Table 2, Entry 4).
The carbonylative Suzuki–Miyaura cross-coupling reac-
tion of more electron-rich aryl iodides was considered as
well. Whereas 4-iodoanisole reacted with phenylboronic
acid to give exclusively desired diaryl ketone 3e in 87%
yield, 2-iodoanisole afforded 3f in moderate yield (65%;
Table 2, Entries 5 and 6). Despite the modest yield ob-
served, the reaction is interesting, as aryl palladium species
with the palladium ortho to a methoxy group normally un-
dergo C–H activation with the methoxy C–H bond, which [a] Reaction conditions:
A mixture of phenylboronic acid
results in several byproducts.[26]
(2.5 equiv.), Pd(OAc)2 (10 mol-%), Mo(CO)6 (1.5 equiv.), and
K2CO3 (3 equiv.) in anisole (0.2 m) was heated in a sealed tube at
140 °C for 12 h.
To cover the aspects of steric hindrance in constructing
diaryl ketones, a notoriously difficult transformation by
Friedel–Crafts acylation, more encumbered iodoarene 1g
was employed. Interestingly, corresponding diaryl ketone 3g
was obtained in high yield (83%; Table 2, Entry 7).
Then, the scope of the reaction using electron-deficient
iodoarenes was explored. ortho-Fluoro- and ortho,para-
dichloro-substituted iodoarenes 1h and 1i provided diaryl
ketones 3h and 3i, good partners for further functionaliza-
tion, in 84 and 60% yield, respectively (Table 2, Entries 8
and 9). Even more electron-poor aryl iodides containing
ortho-trifluoromethyl, carbonyl, and nitro groups, which are
known to be more prone to homocoupling to give biaryls,
Finally, the reactivity of a heteroaryl halide containing a
free OH functionality was investigated. Thus, substrate 1p
and phenylboronic acid gave corresponding unsymmetrical
Scheme 3. Carbonylative coupling of iodoarene 1p and phenylbo-
were tolerated under the reaction conditions, furnished the ronic acid.
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Efficient Synthesis of Unsymmetrical Diaryl Ketones
(2,4-Dimethylphenyl)(phenyl)methanone (3d):[29] Yield: 78%
(33 mg). Yellow solid, m.p. 120–121 °C. 1H NMR (500 MHz,
CDCl3, 25 °C): δ = 7.77–7.81 (m, 2 H), 7.55–7.59 (m, 1 H), 7.41–
7.46 (m, 2 H), 7.23 (d, J = 7.8 Hz, 1 H), 7.11 (s, 1 H), 7.10 (d, J =
7.8 Hz, 1 H), 2.39 (s, 3 H, Me), 2.33 (s, 3 H, Me) ppm. 13C NMR
(125 MHz, CDCl3): δ = 198.5, 140.5, 138.1, 137.3, 135.6, 132.7,
131.9, 130.1, 129.2, 128.3, 125.6, 21.4, 20.0 ppm. C15H14O (210.27):
calcd. C 85.68, H 6.71; found C 85.87, H 6.85.
diaryl ketone 3r in moderate yield, proving that the sub-
strate was tolerated under the reaction conditions
(Scheme 3).
Conclusions
In conclusion, in the presence of Mo(CO)6 and a cata-
lytic amount of palladium acetate, a vide variety of iodoar-
enes were smoothly transformed into the corresponding di-
aryl ketones. Despite the use of K2CO3 as a relatively weak
and compatible base with a number of functional groups,
carbon monoxide liberation was sufficient to suppress bi-
aryl side-product formation, and most diaryl ketones were
exclusively obtained under the optimized reaction condi-
tions. This is the first-offered mild base/solvent combina-
tion for efficient carbon monoxide extrusion from a metal
carbonyl under microwave-free conditions. The presented
methodology looks suitable for high-throughput carbon-
ylation applications.
(4-Methoxyphenyl)(phenyl)methanone (3e): Yield: 87% (37 mg).
White solid, m.p. 60–62 °C (ref.[17] 59–60 °C). 1H NMR (500 MHz,
CDCl3, 25 °C): δ = 7.84 (d, J = 8.8 Hz, 2 H), 7.74–7.76 (m, 2 H),
7.55 (d, J = 7.5 Hz, 1 H), 7.46 (t, J = 7.6 Hz, 2 H), 6.96 (d, J =
8.8 Hz, 2 H), 3.87 (s, 3 H, OMe) ppm. 13C NMR (125 MHz,
CDCl3): δ = 195.4, 163.3, 138.4, 132.5, 131.8, 130.1, 129.6, 128.1,
113.5, 55.4 ppm. C14H12O2 (212.24): calcd. C 79.22, H 5.70; found
C 79.39, H 5.81.
(2-Methoxyphenyl)(phenyl)methanone (3f): Yield: 65% (28 mg). Yel-
low solid, m.p. 38–39 °C (ref.[30] 41 °C). 1H NMR (400 MHz,
CDCl3, 25 °C): δ = 7.80–7.82 (m, 2 H), 7.55 (t, J = 7.2 Hz, 1 H),
7.43–7.46 (m, 3 H), 7.35–7.37 (m, 1 H), 6.98–7.04 (m, 2 H), 3.73
(s, 3 H, OMe) ppm. 13C NMR (100 MHz, CDCl3): δ = 196.5, 157.4,
137.8, 133.0, 131.9, 129.8, 129.6, 128.9, 128.3, 120.5, 111.5,
55.6 ppm. C14H12O2 (212.24): calcd. C 79.22, H 5.70; found C
79.41, H 5.80.
Experimental Section
1-Naphthyl(phenyl)methanone (3g): Yield: 83% (39 mg). White
solid, m.p. 76–77 °C (ref.[31] 76–77 °C). 1H NMR (400 MHz,
CDCl3, 25 °C): δ = 8.10 (d, J = 8.0 Hz, 1 H), 8.00 (d, J = 8.4 Hz,
1 H), 7.93 (t, J = 4.8 Hz, 1 H), 7.87–7.89 (m, 2 H), 7.56–7.63 (m,
2 H), 7.51–7.55 (m, 3 H), 7.45–7.51 (m, 2 H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 198.0, 138.3, 136.3, 133.7, 133.3, 131.2,
131.0, 130.4, 128.5, 128.4, 127.7, 127.2, 126.5, 125.8, 124.3 ppm.
C17H12O (232.28): calcd. C 87.90, H 5.21; found C 87.68, H 5.08.
General Remarks: All reagents, the metal catalyst, and the carbonyl
were commercially available and used as received. The Suzuki
cross-coupling reactions were carried out in an oil bath using Mi-
crowave Vials (2–5 mL). NMR spectra were recorded at room tem-
perature with 400 or 500-MHz spectrometers using CDCl3 as the
solvent.
General Procedure for the Carbonylative Suzuki Coupling Reaction
of Iodoarenes: A vial equipped with a stir bar was charged with
aryl iodide (0.2 mmol, 1.0 equiv.), phenylboronic acid (0.5 mmol,
2.5 equiv.), Pd(OAC)2 (10 mol-%), and Mo(CO)6 (0.3 mmol,
1.5 equiv.). Anisole (0.2 m) was then added and the vial was capped.
The resulting mixture was heated in an oil bath at 140 °C for 12 h,
cooled, and then filtered through a short plug of silica. Removal of
the solvent gave a crude mixture that was purified by flash column
chromatography (hexanes/EtOAc gradient). Spectral and physical
data for all diaryl ketones were compared with authentic samples
and were in agreement with previously reported data.
(2-Fluorophenyl)(phenyl)methanone (3h):[32] Yield: 84% (34 mg).
1
Yellow oil. H NMR (400 MHz, CDCl3, 25 °C): δ = 7.15–7.21 (m,
1 H), 7.27–7.31 (m, 1 H), 7.47–7.65 (m, 5 H), 7.88–7.90 (m, 2 H)
ppm. C13H9FO (200.21): calcd. C 77.99, H 4.53; found C 77.71, H
4.39.
(2,4-Dichlorophenyl)(phenyl)methanone (3i):[33] Yield: 60% (30 mg).
White solid, m.p. 46–47 °C. 1H NMR (400 MHz, CDCl3, 25 °C): δ
= 7.77–7.80 (m, 2 H), 7.59–7.61 (m, 1 H), 7.45–7.49 (m, 3 H), 7.32–
7.35 (m, 2 H) ppm. C13H8Cl2O (251.11): calcd. C 62.18, H 3.21;
found C 62.37, H 3.32.
(2-Methylphenyl)(phenyl)methanone (3a):[27] Yield: 78% (31 mg).
1
Methyl 2-Benzoylbenzoate (3k): Yield: 60% (29 mg). White solid,
m.p. 49–51 °C (ref.[34] 48–49.5 °C). 1H NMR (400 MHz, CDCl3,
25 °C): δ = 8.04–8.07 (m, 1 H), 7.40–7.77 (m, 8 H), 3.61 (s, 3 H,
CO2Me) ppm. 13C NMR (400 MHz, CDCl3): δ = 197.1, 166.3,
141.6, 137.2, 133.1, 132.4, 130.2, 129.6, 129.2, 129.0, 128.5, 127.7,
52.1 ppm. C15H12O3 (240.25): calcd. C 74.99, H 5.03; found C
74.77, H 4.91.
Oil. H NMR (400 MHz, CDCl3, 25 °C): δ = 7.78 (d, J = 8.4 Hz,
2 H), 7.55–7.62 (m, 1 H), 7.24–7.49 (m, 6 H), 2.32 (s, 3 H, Me)
ppm. 13C NMR (100 MHz, CDCl3): δ = 198.5, 138.5, 137.7, 136.8,
133.0, 130.9, 130.1, 130.0, 128.4, 128.3, 125.1, 19.9 ppm. C14H12O
(196.24): calcd. C 85.68, H 6.16; found C 85.49, H 6.06.
Benzophenone (3b):[28] Yield: 86% (31 mg). White solid, m.p. 48–
1
49 °C (ref.[28b] 47–49 °C). H NMR (500 MHz, CDCl3, 25 °C): δ =
7.80–7.83 (m, 4 H), 7.59–7.61 (m, 2 H), 7.48–7.51 (m, 4 H) ppm.
13C NMR (125 MHz, CDCl3): δ = 195.9, 137.2, 131.9, 129.5,
127.9 ppm.
N-(2-Benzoylphenyl)methanesulfonamide (3m): Yield: 61% (34 mg).
White solid, m.p. 107–108 °C (ref.[35] 108 °C). 1H NMR (400 MHz,
CDCl3, 25 °C): δ = 10.28 (s, 1 H, NH), 7.80–7.82 (m 1 H), 7.68–
7.70 (m, 2 H), 7.56–7.64 (m, 3 H), 7.47–7.52 (m, 2 H), 7.09–7.12
(m, 1 H), 3.08 (s, 3 H, SO2Me) ppm. C14H13NO3S (275.32): calcd.
C 61.07, H 4.76, N 5.09, S 11.65; found C 61.30, H 4.87, N 5.21,
S 11.81.
(4-Methylphenyl)(phenyl)methanone (3c): Yield: 90% (35 mg). Yel-
low solid, m.p. 57–58 °C (ref.[17] 56–57 °C). 1H NMR (500 MHz,
CDCl3, 25 °C): δ = 7.77–7.79 (m, 2 H), 7.72 (d, J = 8.1 Hz, 2 H),
7.56 (t, J = 7.5 Hz, 1 H), 7.44 (t, J = 7.5 Hz, 2 H), 7.27 (d, J =
8.1 Hz, 2 H), 2.44 (s, 3 H, Me) ppm. 13C NMR (125 MHz, CDCl3): (4-Chlorophenyl)(phenyl)methanone (3n):[36] Yield: 81% (35 mg).
δ = 196.5, 143.2, 137.9, 134.9, 132.2, 130.2, 129.8, 128.8, 128.1,
21.7 ppm. C14H12O (196.24): calcd. C 85.68, H 6.16; found C 85.47,
H 6.01.
White solid, m.p. 74–75 °C (ref.[17] 73–74 °C). 1H NMR (400 MHz,
CDCl3, 25 °C): δ = 7.74–7.78 (m, 4 H), 7.63 (t, J = 7.8 Hz, 1 H),
7.47–7.51 (m, 4 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 195.5,
Eur. J. Org. Chem. 2011, 2128–2132
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F. Jafarpour, P. Rashidi-Ranjbar, A. O. Kashani
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138.9, 137.3, 135.9, 132.6, 131.5, 129.9, 128.6, 128.4 ppm.
C13H9ClO (216.66): calcd. C 72.07, H 4.19; found C 71.89, H 4.09.
(4-Methoxyphenyl)(p-tolyl)methanone (3o): Yield: 78% (35 mg).
White solid, m.p. 87–89 °C (ref.[17] 88–89 °C). 1H NMR (400 MHz,
CDCl3, 25 °C): δ = 7.80–7.83 (m, 2 H), 7.69 (d, J = 8.0 Hz, 2 H),
7.28 (d, J = 8.3 Hz, 2 H), 6.95–6.98 (m, 2 H), 3.90 (s, 3 H, OMe),
2.44 (s, 3 H, Me) ppm. 13C NMR (100 MHz, CDCl3): δ = 195.4,
163.0, 142.6, 135.5, 132.5, 130.5, 130.0, 128.9, 113.5, 55.5,
21.6 ppm. C15H14O2 (226.27): calcd. C 79.62, H 6.24; found C
79.85, H 6.38.
(Pyridin-3-yl)(p-tolyl)methanone (3p):[18] Yield: 85% (34 mg). White
solid, m.p. 77–78 °C. 1H NMR (400 MHz, CDCl3, 25 °C): δ = 8.97
(s, 1 H), 8.80 (d, J = 3.2 Hz, 1 H), 8.08–8.10 (m, 1 H), 7.72 (d, J
= 7.5 Hz, 2 H), 7.44 (d, J = 4.8 Hz, 1 H), 7.31 (d, J = 7.5 Hz, 2
H), 2.45 (s, 3 H, Me) ppm. 13C NMR (100 MHz, CDCl3): δ =
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of Tehran. We thank Sara Izadi (University of Tehran) for practical
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Received: December 28, 2010
Published Online: February 25, 2011
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