Highly regioselective α-arylation of coumarins via palladium-catalyzed C-H activation/desulfitative coupling

Article abstract of DOI:10.1002/adsc.201300707

A novel regioselective α-arylation of coumarins with readily available arenesulfonyl chlorides and sodium arenesulfinates via palladium-catalyzed direct C-H functionalizations under mild reaction conditions is described. This protocol presents an unexpected and highly regio-controlled arylation of coumarins at C-3 to construct interesting 3-arylcoumarins with fascinating biological and fluorescent properties. The regioselectivity observed is in sharp contrast with that expected for the Heck reactions. Copyright

Full text of DOI:10.1002/adsc.201300707

COMMUNICATIONS
DOI: 10.1002/adsc.201300707
Highly Regioselective a-Arylation of Coumarins via Palladium-
À
Catalyzed C H Activation/Desulfitative Coupling
Farnaz Jafarpour,a,* Mina Barzegar Amiri Olia,a and Hamideh Hazratia
a
School of Chemistry, College of Science, University of Tehran, 14155-6455 Tehran, Iran
Fax : (+98)-21-6649-5291; e-mail: jafarpur@khayam.ut.ac.ir
Received: August 6, 2013; Revised: September 18, 2013; Published online: November 13, 2013
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201300707.
Abstract: A novel regioselective a-arylation of cou-
marins with readily available arenesulfonyl chlor-
ides and sodium arenesulfinates via palladium-cata-
routes. Recently, we and other groups made some ad-
vances in the direct C-4 arylation of coumarins via
the palladium-catalyzed oxidative Heck-type reaction
of coumarins with arylboronic acids.[7] The strategy
was further improved by Hong et al.[8] via a two-fold
À
lyzed direct C H functionalizations under mild re-
action conditions is described. This protocol pres-
ents an unexpected and highly regio-controlled ary-
lation of coumarins at C-3 to construct interesting
3-arylcoumarins with fascinating biological and flu-
orescent properties. The regioselectivity observed is
in sharp contrast with that expected for the Heck
reactions.
À
C H activation of coumarins and simple arenes
where the regioselectivity was reflected in a bias for
C-4 arylation which is an expected regioselectivity in
Heck reactions.[9]
a-Functionalization of unsaturated carbonyl com-
pounds is a desirable but challenging strategy due to
the requisite for prefunctionalizations at the a-posi-
tion (Scheme 1, path b).[10] For instance, the Suzuki
cross-coupling of arylboronic acids and 3-halocoumar-
ins provides a route to 3-arylcoumarins which still
needs prefunctionalization of the coumarins.[11] Very
recently, we also reported a palladium-catalyzed de-
carboxylative arylation of coumarin-3-carboxylic acids
À
Keywords: a-arylation; 3-arylcoumarins; C H acti-
vation; desulfitative arylation; palladium
Arylcoumarins have attracted considerable attention using iodoarenes where the carboxylate group war-
because of their extraordinary biological and pharma- ranted regioselective arylation at C-3.[12]
cological activities and their presence in a variety of
To the best of our knowledge, despite the impor-
natural products.[1] In addition, their applications in tance of direct a-arylation of a,b-unsaturated carbon-
À
laser and dispersed fluorescent dyes, optical brighten- yl compounds via C H activation process only rare
ers and emission layers (OLED) make this skeleton
noteworthy.[2] Furthermore, these privileged structural
motifs have been characterized as potent and selec-
tive monoamine oxidase inhibitors and are used
in the treatment of neurological disorders such as
depression, anxiety, Parkinsonꢀs and Alzheimerꢀs
diseases.[3]
Among various methods, transition metal-catalyzed
cross-couplings such as Heck and Suzuki reactions
À
have revolutionized C C bond formation in synthetic
strategies and functionalization of a,b-unsaturated
carbonyl compounds as well.[4] It is well documented
that in Heck-type reactions while electron-deficient
olefins yield exclusively the b-arylated products[5]
(Scheme 1, path a), electron-rich olefins generate
a mixture of both a- and b-arylated ones.[6] Thus, the
regioselectivity of the Heck reaction is the main point
which must be considered in planning synthetic turated carbonyl compounds.
Scheme 1. Transition metal-catalyzed arylation of a,b-unsa-
Adv. Synth. Catal. 2013, 355, 3407 – 3412
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3407

Farnaz Jafarpour et al.
COMMUNICATIONS
Table 1. Optimization of desulfitative arylation of coumarin
1a.[a]
examples are reported which usually suffer from low
functional group tolerance, low yields of adducts and
harsh reaction conditions.[13]
Entry [Pd]
[O]
L
Base
Yield
[%]
Meanwhile, the recently increasing interest toward
the use of inexpensive and readily available arenesul-
fonyl chlorides, hydrazides, acids and their sodium
salts as potential aryl sources in transition metal
cross-coupling reactions has become apparent.[14]
These thioorganic coupling partners can readily un-
1
2
3
4
Pd
PdCl2
Pd(dba)2
PdCl2
PdCl2
PdCl2
G
PPh3 AgOAc 10
PPh3 AgOAc 12
PPh3 AgOAc
PPh3 Cs2CO3
PPh3 K2CO3
0
0
0
5
À
dergo C S bond cleavage to liberate SO2 under mild
6
PPh3 NaHCO3 31
PPh3 Ag2CO3 32
reaction conditions with no requisite for an ortho-
electron-donating or -electron-withdrawing substitu-
tion (required in carboxylic acids). Very recently,
these compounds have been successfully used as ary-
lating agents in cross-coupling,[15] homo-coupling[16]
and also Heck-type reactions where b-regioselectivity
was given in all cases.[17,18]
7[b]
8
PdACHTUNTGRENNUNG
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
PdCl2
ACHTUGNTRENN(NUG OAc)2 PPh3 NaHCO3 62
9
CuCl2
CuSO4
ZnCl2
PPh3 NaHCO3 40
PPh3 NaHCO3 38
PPh3 NaHCO3 57
10
11
12
13
14
15
16
17
18
19[b]
20
21
22
Zn
(OAc)2 PPh3 NaHCO3
0
0
0
ZnI2
PPh3 NaHCO3
PPh3 NaHCO3
Ag2CO3
AgOAc
Ag2O
Na2S2O8
G
In continuation of our interest in the direct aryla-
tion of heterocycles, herein we report our new find-
ings that an a-regioselectivity in direct arylation of
coumarins can be achieved by employing either are-
nesulfonyl chloride or sodium arenesulfinate coupling
partners in the presence of catalytic amounts of palla-
dium. This protocol allows for a waste minimized con-
struction of biologically interesting 3-arylcoumarins in
high yields using inexpensive sulfonyls or sulfinates
and precluding prefunctionalization of coumarins. Re-
gioselectivity, broad substrate scope and mild reaction
conditions with no requisite for any ligands or bases
are the advantages of the present work.
PPh3 NaHCO3 54
PPh3 NaHCO3 17
PPh3 NaHCO3 14
(NH4)2S2O8 PPh3 NaHCO3
0
Cu
A
NaHCO3 67
Cu
A
78
5
58
ZnCl2
AgOAc
[a]
Reaction conditions: p-toluenesulfonyl chloride 2a
(0.1 mmol, 1 equiv.), coumarin 1a (0.3 mmol, 3 equiv.),
Pd catalyst (10 mol%), oxidant (1 equiv.), ligand
(20 mol%), base (2 equiv.), 4ꢂ MS in 1,4-dioxane
(0.2M) at 808C for 24 h.
[b]
To achieve the purpose of desulfitative arylation of
coumarins, first coumarin 1a and para-toluenesulfonyl
chloride 2a were chosen as the model compounds and
Base (1 equiv.) used.
the reaction parameters (catalyst, solvent, base, etc.) and base-free conditions, lower yields were obtained
were varied (Table 1). Our preliminary results re- (entries 21 and 22).
vealed that palladium/PPh3 catalytic systems with
AgOAc as base in 1,4-dioxane were not effective and CuACHTUNGTRENNUNG
We were pleased to find that the use of the PdCl2/
(OAc)2 in 1,4-dioxane provided the desired 3-aryl-
only traces of the desired product were obtained (en- coumarin 3a with high regioselectivity in 78% isolated
tries 1–3). Screening reactions with respect to bases yield. An excess amount of coumarin ensured the
such as Cs2CO3, Na2CO3, K2CO3, NaHCO3 and complete conversion of starting material to the de-
Ag2CO3 resulted in slightly increased yields (en- sired 3-arylcoumarin and the excess of unreacted cou-
tries 4–6).
marin was recovered at the end of the reaction. It is
Applying conditions similar to Dongꢀs work also noteworthy that the 4-arylated coumarin was not ob-
did not provide satisfactory results (entry 7).[15m] Ex- served in the reaction mixture.
ploration of a variety of oxidants including copper,
The scope of both starting materials compatible
zinc, silver and persulfate salts proved Cu(OAc)2·H2O with the direct arylation reaction was next investigat-
AHCTUNGTRENNUNG
as the most effective one where regioselective aryla- ed. Accordingly, coumarins and arenesulfonyl chlor-
tion of coumarin at C-3 was achieved in 62% yield ides with various electron-donating and electron-with-
(entries 8–18). Furthermore, it turned out that in the drawing groups (alkyl, alkoxy, hydroxy and nitro
absence of any ligands, a comparable yield of the groups) were tested and a broad reaction scope was
product was obtained and therefore, ligand-free con- established (Table 2). Reaction of coumarin 1a with
ditions were established for later investigations arenesulfonyl chlorides possessing various steric and
(entry 19). Notably, base removal from the reaction electronic properties resulted in good to high yields of
conditions, even improved the yield further 3-arylcoumarins (entries 1–4). More sterically encum-
(entry 20). When other oxidants such as ZnCl2 and bered naphthalenesulfonyl chloride 2e underwent the
AgOAc were subsequently explored under ligand- desulfitative arylation reaction in a relatively lower
yield (entry 5). 6-Methylcoumarin 1b also afforded
3408
asc.wiley-vch.de
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2013, 355, 3407 – 3412

À
Highly Regioselective a-Arylation of Coumarins via Palladium-Catalyzed C H Activation
Table 2. Scope of regioselective desulfitative arylation of
coumarins.[a]
Entry R1
R2
Product Yield [%]
Scheme 2. Desulfitative arylation of coumarins with sodium
arenesulfinates.
1
2
3
4
5
6
7
8
H 1a
H 1a
H 1a
H 1a
4-CH3 2a
4-OMe 2b
4-pentyl 2c
H 2d
3a
3b
3c
3d
3e
78 (72)[b]
66
72
68
47
75
63
80
66
57
64
72
65
87
60
traces
Motivated by these results, we next sought to
expand the scope of regioselective direct arylation of
coumarin at C-3 with arenesulfonyl chlorides to
sodium sulfinates (Scheme 2). These compounds are
more stable and moisture-insensitive compared to sul-
fonyl chlorides. Gratifyingly, the arylation reaction of
coumarin 1a with sodium benzenesulfinate 4a under
slightly altered reaction conditions afforded the de-
sired 3-arylcoumarin 3d albeit in moderate yield. Var-
ious coumarins arylated at C-3 were also obtained
employing by alkyl- and alkoxy-substituted sodium
sulfinates in yields ranging 58–67% (Scheme 2).
H 1a
2-naphthyl 2e
6-Me 1b
6-Me 1b
6-Me 1b
6-Me 1b
7-NEt2 1c
7-OEt 1d
6-OMe 1e H 2d
7-OMe 1f 2-naphthyl 2e
7-OMe 1f 4-CH3 2a
4-CH
N
2-naphthyl 2e
4-CH3 2a
H 2d
H 2d
4-OMe 2b
3g
3h
3i
3j
3k
3l
3m
3n
3o
3p
9
10
11
12
13
14
15
16
7-OH 1g
6-NO2 1h
H 2d
4-CH3 2a
[a]
[b]
All reactions were run under the optimized conditions.
A 1.0 mmol scale was performed employing 5 mol%
PdCl2.
Additionally, continuing our efforts in the direct ar-
ylation of heterocycles[21] we turned our attention to
apply this protocol to the important concept of the
direct arylation of pyrroles. Although some focused
the desired products in high yields exceeding 63% efforts on regioselective desulfitative arylation of
(entries 6–9). This has significant synthetic utility some fused heterocycles including indoles, benzoxa-
based on interesting biological activities of 6-methyl- zoles, thiazoles, imidazoles and 1,2,4-oxadiazoles with
3-arylcoumarins.[3c] Next the scope of the reaction was sodium sulfinates were reported,[15d,f,j–l] the direct ary-
explored with more electron-rich coumarins. Coumar- lation of pyrroles to the best of our knowledge is un-
ins bearing amine and alkoxy groups also resulted in precedented. 2-Arylpyrroles have fascinating biologi-
the corresponding arylcoumarins within a range of cal and pharmacological activities. For instance, anal-
57–87% isolated yields (entries 10–14). Gratifyingly, gesic and anti-inflammatory properties of these struc-
even sensitive functionalities such as hydroxy groups tural motifs are reported.[22] Additionally, 2-arylpyr-
were also tolerated under the optimized reaction con- roles are known to act as novel anticoccidial and
ditions and the reaction could be performed without antifungal agents.[23] In this regard, the reaction of N-
protection of OH groups (entry 15).[19] Hydroxycou- methylpyrrole with sulfonyl chlorides 2a and 2d under
marins have been proved to act as potent metal chela- some further optimized reaction conditions was ex-
tors, free radical scavengers and powerful chain- plored and pleasingly regioselective arylation of pyr-
breaking antioxidants. They also show different cyto- roles at C-2 was achieved in the presence of
toxic values according to the positions of the OH PdACHTNUTRGENN(UG OAc)2/CuACHTUTGNREN(NUNG OAc)2 and addition of KOAc in DMA
groups in their structures.[20] We also investigated the (Scheme 3). Further optimization and development of
reaction scope with electron-deficient coumarins with the scope of the reaction was then undertaken.
a nitro substituent. The corresponding arylated cou-
marin was obtained only in trace amounts under the
optimized reaction conditions (entry 16). Further-
more, we sought to expand the scope of the reaction
to include aliphatic sulfonyl chlorides. Unfortunately,
benzyl- and methanesulfonyl chloride remained un-
reacted under the reaction conditions. Finally, we per-
formed a 1.0-mmol scale experiment employing
5 mol% PdCl2 which gratifyingly offered arylcoumar-
Scheme 3. Desulfitative arylation of pyrroles with arenesul-
in 3a in 72% isolated yield (Table 1, entry 1).
fonyl chlorides.
Adv. Synth. Catal. 2013, 355, 3407 – 3412
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
3409

Farnaz Jafarpour et al.
COMMUNICATIONS
Finally, the regioselectivity in desulfitative direct ar- fluorescent dyes. The observed regioselectivity was re-
ylation of terminal alkenes under the optimized reac- flected in a bias for arylation at C-3 instead of C-4
tion conditions was examined. The results showed and in almost all cases 4-arylcoumarins were not ob-
that with an acyclic electron-deficient alkene such as served. Furthermore, mild ligand- and base-free con-
methyl acrylate, desulfitative arylation occurred ex- ditions were established in the desulfitative arylations
clusively at the least-substituted terminal b-position using this arenesulfonyl chloride approach, which was
of the double bond (Scheme 4).[24]
not feasible in most of the previously reported a-ary-
Although the exact mechanism of this reaction is lation reactions. In addition, the scope was readily ex-
not clear, possible pathway is proposed in tended to the direct regioselective arylation of pyr-
a
Scheme 5. The first step is oxidative addition of palla- roles leading to biologically interesting 2-arylpyrroles.
À
dium into S Cl bond of arenesulfonyl chloride to gen-
erate intermediate A which goes a desulfitative pro-
cess to form arylpalladium species B.[25] In the other Experimental Section
À
cycle, C H activation of coumarin generates inter-
mediate C[26] which undergoes transmetallation[27] Typical Experimental Procedure for Arylation of
with B to produce diarylpalladium D followed by a re- Coumarins with Arenesulfonyl Chlorides
ductive elimination process to afford the desired
product.
A vial equipped with a stir bar was charged with toluenesul-
fonyl chloride (0.1 mmol, 1 equiv.), coumarin (3 equiv.),
Although the exact role of the copper salt is not
clear, it was postulated that the copper salt can play
the role of a palladium reoxidant and contribute in
the desulfonation process to form the aryl metal spe-
cies.[13a,28]
In summary, we have developed a novel, versatile,
highly regioselective and step-economical desulfita-
tive arylation of coumarins with arenesulfonyl chlor-
ides and sodium sulfinates via a palladium catalytic
system. The protocol exhibits a simple and new route
to interesting 3-arylcoumarins that serve as the key
intermediates in the synthesis of drug candidates and
PdCl2 (10 mol%), CuACTHNUGRTNE(NUG OAc)2 (1 equiv.) and 4ꢂ MS. 1,4-Di-
oxane (0.2M) was added and the vial was capped. The re-
sulting mixture was heated in an oil bath at 808C for 24 h,
cooled then filtered through a short plug of silica. Removal
of the solvent gave a crude mixture which was purified by
flash column chromatography (hexane/EtOAc gradient).
3-(4-Methylphenyl)-2H-chromen-2-one (3a): Yellowish
solid; yield: 18 mg (78%); mp 160–1628C (ref.[29] 1618C);
1H NMR (300 MHz, CDCl3): d=7.71 (s, 1H), 7.58 (d, J=
7.3 Hz, 2H), 7.49–7.44 (m, 2H), 7.29–7.22 (m, 2H), 7.22 (d,
J=7.3 Hz, 2H), 2.35 (s, 3H); 13C NMR (100 MHz, CDCl3):
d=21.4, 116.5, 119.9, 124.7, 128.0, 128.4, 128.5, 129.3, 129.8,
131.3, 132.0, 139.0, 139.4, 153.5, 160.9; anal. calcd. for
C16H12O2: C 81.34, H 5.12; found: C 81.65, H 5.26.
Acknowledgements
We acknowledge the financial support of the Iran National
Science Foundation (INSF) and the University of Tehran.
Scheme 4. Desulfitative arylation of methyl acrylate.
Scheme 5. A plausible mechanism for regioselective desulfitative arylation of coumarins.
3410
asc.wiley-vch.de
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2013, 355, 3407 – 3412

À
Highly Regioselective a-Arylation of Coumarins via Palladium-Catalyzed C H Activation
À
References
[9] For selected general reviews on metal-catalyzed C H
bond functionalizations see: a) S. I. Kozhushkov, L. Ac-
kermann, Chem. Sci. 2013, 4, 886–896; b) K. M. Engle,
T.-S. Mei, M. Wasa, J.-Q. Yu, Acc. Chem. Res. 2012, 45,
788–802; c) N. Kuhl, M. N. Hopkinson, J. Wencel-
Delord, F. Glorius, Angew. Chem. 2012, 124, 10382–
10401; Angew. Chem. Int. Ed. 2012, 51, 10236–10254;
d) P. B. Arockiam, C. Bruneau, P. H. Dixneuf, Chem.
Rev. 2012, 112, 5879–5918; e) M. C. White, Synlett 2012,
23, 2746–2748; f) J. Wencel-Delord, T. Drçge, F. Liua,
F. Glorius, Chem. Soc. Rev. 2011, 40, 4740–4761; g) B. J.
Stokes, T. G. Driver, Eur. J. Org. Chem. 2011, 4071–
4088; h) T. Newhouse, P. S. Baran, Angew. Chem. 2011,
123, 3422–3435; Angew. Chem. Int. Ed. 2011, 50, 3362–
3374; i) M. Schnꢅrch, N. Dastbaravardeh, M. Ghobrial,
B. Mrozek, M. D. Mihovilovic, Curr. Org. Chem. 2011,
15, 2694–2730; j) S. H. Cho, J. Y. Kim, J. Kwak, S.
Chang, Chem. Soc. Rev. 2011, 40, 5068–5083; k) D. A.
Colby, R. G. Bergman, J. A. Ellman, Chem. Rev. 2010,
110, 624–655.
[1] a) J. Yang, G.-Y. Liu, F. Dai, X.-Y. Cao, Y.-F. Kang, L.-
M. Hu, J.-J. Tang, X.-Z. Li, Y. Li, X.-L. Jin, B. Zhou,
Bioorg. Med. Chem. Lett. 2011, 21, 6420–6425; b) M.
Roussaki, C. A. Kontogiorgis, D. Hadjipavlou-Litina, S.
Hamilakis, A. Detsi, Bioorg. Med. Chem. Lett. 2010,
20, 3889–3892; c) Coumarins – Biology, Applications,
Mode of Action, (Eds.: R. OꢀKennedy, R. D. Thornes),
Wiley, New York, 1997.
[2] For some recent examples see: a) C. H. Chang, H. C.
Cheng, Y. J. Lu, K. C. Tien, H. W. Lin, C. L. Lin, C. J.
Yang, C. C. Wu, Org. Electron. 2010, 11, 247–254;
b) M. T. Lee, C. K. Yen, W. P. Yang, H. H. Chen, C. H.
Liao, C. H. Tsai, C. H. Chen, Org. Lett. 2004, 6, 1241–
1244; c) S. A. Swanson, G. M. Wallraff, J. P. Chen, W. J.
Zhang, L. D. Bozano, K. R. Carter, J. R. Salem, R.
Villa, J. C. Scott, Chem. Mater. 2003, 15, 2305–2312;
d) P. D. Edwards, R. C. Mauger, K. M. Cottrell, F. X.
Morris, K. K. Pine, M. A. Sylvester, C. W. Scott, S. T.
Furlong, Bioorg. Med. Chem. Lett. 2000, 10, 2291–2294;
e) A. Adronov, S. L. Gilat, J. M. Frꢃchet, K. Ohta,
F. V. R. Neuwahl, G. R. Fleming, J. Am. Chem. Soc.
2000, 122, 1175–1185.
[3] For some selected examples see: a) P. Anand, B. Singh,
N. Singh, Bioorg. Med. Chem. 2012, 20, 1175–1180;
b) M. J. Matos, C. Terꢄn, Y. Pꢃrez-Castillo, E. Uriarte,
L. Santana, D. ViÇa, J. Med. Chem. 2011, 54, 7127–
7137; c) M. J. Matos, D. ViÇa, E. Quezada, C. Picciau,
G. Delogu, F. Orallo, L. Santana, E. Uriarte, Bioorg.
Med. Chem. Lett. 2009, 19, 3268–3270.
[4] L. Anastasia, E.-I. Negishi, in: Handbook of Organo-
palladium Chemistry for Organic Synthesis, (Ed.: E.-I
Negishi), John Wiley & Sons, New York, 2002.
[5] For some selected example see: a) Y. Izawa, C. Zheng,
S. S. Stahl, Angew. Chem. 2013, 125, 3760–3763; Angew.
Chem. Int. Ed. 2013, 52, 3672–3675; b) S. Harada, H.
Yano, Y. Obora, ChemCatChem 2013, 5, 121–125;
c) M.-T. Ma, J.-M. Lu, Tetrahedron 2013, 69, 2102–
2106; d) N. Kuuloja, M. Vaismaa, R. Franzꢃn, Tetrahe-
dron 2012, 68, 2313–2318; e) Y. Liu, D. Li, C.-M. Park,
Angew. Chem. 2011, 123, 7471–7474; Angew. Chem.
Int. Ed. 2011, 50, 7333–7336; f) A. L. Gottumukkala,
J. F. Teichert, D. Heijnen, N. Eisink, S. van Dijk, C.
Ferrer, A. van den Hoogenband, A. J. Minnaard, J.
Org. Chem. 2011, 76, 3498–3501; g) A. Nejjar, C. Pinel,
L. Djakovitch, Adv. Synth. Catal. 2003, 345, 612–619;
h) F. Gini, B. Hessen, A. J. Minnaard, Org. Lett. 2005,
7, 5309–5312; i) M. Dams, D. E. De Vos, S. Celen, P. A.
Jacobs, Angew. Chem. 2003, 115, 3636–3639; Angew.
Chem. Int. Ed. 2003, 42, 3512–3515.
[6] a) J. Ruan, J. Xiao, Acc. Chem. Res. 2011, 44, 614–626;
b) M. McConville, J. Ruan, J. Blacker, J. Xiao, Org.
Biomol. Chem. 2010, 8, 5614–5619, and references cited
therein.
[7] a) M. Khoobi, M. Alipour, S. Zarei, F. Jafarpour, A.
Shafiee, Chem. Commun. 2012, 48, 2985–2987; b) Y. Li,
Z. Qi, H. Wang, X. Fu, C. Duan, J. Org. Chem. 2012,
77, 2053–2057.
[10] a) J. C. Banks, D. V. Mele, C. G. Frost, Tetrahedron
Lett. 2006, 47, 2863–2866; b) M. C. Willis, J. Chauhan,
W. G. Whittingham, Org. Biomol. Chem. 2005, 3, 3094–
3095; c) N. V. Lukahev, G. V. Latyshev, P. A. Donez,
G. A. Skryabin, I. P. Beletskaya, Synthesis 2005, 1578–
1580; d) Q. Zhu, J. Wu, R. Fathi, Z. Yang, Org. Lett.
2002, 4, 3333–3336; e) E. Negishi, Z. Tan, S. Y. Liou,
B. Q. Liao, Tetrahedron 2000, 56, 10197–10207.
[11] a) K. Welser, J. Grilj, E. Vauthey, J. W. Aylott, W. C.
Chan, Chem. Commun. 2009, 37, 671–673; b) M. S.
Schiedel, C. A. Briehn, P. Bauerle, Angew. Chem. 2001,
113, 4813–4816; Angew. Chem. Int. Ed. 2001, 40, 4677–
4680.
[12] F. Jafarpour, S. Zarei, M. B. A. Olia, N. Jalalimanesh, S.
Rahiminejadan, J. Org. Chem. 2013, 78, 2957–2964.
[13] a) Y. W. Kim, M. J. Niphakis, G. I. Georg, J. Org.
Chem. 2012, 77, 9496–9503; b) L. Bi, G. I. Georg, Org.
Lett. 2011, 13, 5413–5415; c) S. Martins, P. S. Branco,
M. C. de La Torre, M. A. Sierra, A. Pereira, Synlett
2010, 2918–2922; d) T. Konno, S. Yamada, A. Tani, M.
Nishida, T. Miyabe, T. Ishihara, J. Fluorine Chem. 2009,
130, 913–921; e) H. Ge, M. J. Niphakis, G. I. Georg, J.
Am. Chem. Soc. 2008, 130, 3708–3709.
[14] For reviews see: a) S. G. Modha, V. P. Mehta, E. V. Van
der Eycken, Chem. Soc. Rev. 2013, 42, 5042–5055;
b) S. R. Dubbaka, P. Vogel, Angew. Chem. 2005, 117,
7848–7859; Angew. Chem. Int. Ed. 2005, 44, 7674–7684.
[15] For recent examples see: a) F. Zhao, Q. Tan, F. Xiao, S.
Zhang, G.-J. Deng, Org. Lett. 2013, 15, 1520–1523; b) J.
Colomb, T. Billard, Tetrahedron Lett. 2013, 54, 1471–
1474; c) J.-B. Liu, H. Yan, H.-X. Chen, Y. Luo, J. Weng,
G. Lu, Chem. Commun. 2013, 49, 5268–5270; d) M.
Wu, J. Luo, F. Xiao, S. Zhang, G.-J. Deng, H.-A. Luo,
Adv. Synth. Catal. 2012, 354, 335–340; e) C. Zhou, Q.
Liu, Y. Li, R. Zhang, X. Fu, C. Duan, J. Org. Chem.
2012, 77, 10468–10472; f) M. Wang, D. Li, W. Zhou, L.
Wang, Tetrahedron 2012, 68, 1926–1930; g) X. Yu, X.
Li, B. Wan, Org. Biomol. Chem. 2012, 10, 7479–7482;
h) S. Chen, K. Zheng, F. Chen, Tetrahedron Lett. 2012,
53, 6297–6299; i) X. Zhao, V. M. Dong, Angew. Chem.
2011, 123, 962–964; Angew. Chem. Int. Ed. 2011, 50,
932–934; j) B. Liu, Q. Guo, Y. Cheng, J. Lan, J. You,
[8] M. Min, S. Hong, Chem. Commun. 2012, 48, 9613–
9615.
Adv. Synth. Catal. 2013, 355, 3407 – 3412
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
3411

Farnaz Jafarpour et al.
COMMUNICATIONS
Chem. Eur. J. 2011, 17, 13415–13419; k) M. Zhang, S.
Zhang, M. Liu, J. Cheng, Chem. Commun. 2011, 47,
11522–11524; l) R. Chen, S. Liu, X. Liu, L. Yang, G.-J.
Deng, Org. Biomol. Chem. 2011, 9, 7675–7679; m) X.
Zhao, E. Dimitrijevic, V. M. Dong, J. Am. Chem. Soc.
2009, 131, 3466–3467; n) M. Chandra, R. Volla, S. R.
Dubbaka, P. Vogel, Tetrahedron 2009, 65, 504–511.
[16] For some selected examples, see: a) B. Rao, W. Zhang,
L. Hu, M. Luo, Green Chem. 2012, 14, 3436–3440;
b) S. R. Dubbaka, P. Vogel, Tetrahedron Lett. 2006, 47,
3345–3348.
[17] a) S. Hua, P. Xia, K. Cheng, C. Qi, Appl. Organomet.
Chem. 2013, 27, 188–190; b) W. Chen, H. Chen, F.
Xiao, G.-J. Deng, Org. Biomol. Chem. 2013, 11, 4295–
4298; c) H. Wang, Y. Li, R. Zhang, K. Jin, D. Zhao, C.
Duan, J. Org. Chem. 2012, 77, 4849–4853; d) W. Chen,
X. Zhou, Fu. Xiao, J. Luo, G.-J. Deng, Tetrahedron
Lett. 2012, 53, 4347–4350; e) A. R. Hajipour, F. Rafiee,
A. E. Rouho, Tetrahedron Lett. 2011, 52, 4782–4787;
f) G.-W. Wang, T. Miao, Chem. Eur. J. 2011, 17, 5787–
5790.
[22] M. Anzini, A. D. Capua, S. Valenti, S. Brogi, M.
Rovini, G. Giuliani, A. Cappelli, S. Vomero, L. Chias-
serini, A. Sega, G. Poce, G. Giorgi, V. Calderone, A.
Martelli, L. Testai, L. Sautebin, A. Rossi, S. Pace, C.
Ghelardini, L. Di C. Mannelli, V. Benetti, A. Giordani,
P. Anzellotti, M. Dovizio, P. Patrignani, M. Biava, J.
Med. Chem. 2013, 56, 3191–3206.
[23] a) T. Biftu, D. Feng, M. Ponpipom, N. Girotra, G.-B.
Liang, X. Qian, R. Bugianesi, J. Simeone, L. Chang, A.
Gurnett, P. Liberator, P. Dulski, P. S. Leavitt, T. Crum-
ley, A. Misura, T. Murphy, S. Rattray, S. Samaras, T.
Tamas, J. Mathew, C. Brown, D. Thompson, D.
Schmatz, M. Fisher, M. Wyvratt, Bioorg. Med. Chem.
Lett. 2005, 15, 3296–3301; b) G. H. Jana, S. Jain, S. K.
Arora, N. Sinha, Bioorg. Med. Chem. Lett. 2005, 15,
3592–3595.
[24] a) X. Zhou, J. Luo, J. Liu, S. Peng, G. J. Deng, Org.
Lett. 2011, 13, 1432–1435; b) G. Wang, T. Miao, Chem.
Eur. J. 2011, 17, 5787–5790.
[25] T. Kashiwabara, M. Tanaka, Tetrahedron Lett. 2005, 46,
7125–7128.
[18] Miscellaneous examples: a) S. Liu, Y. Bai, X. Cao, F.
Xiao, G.-J. Deng, Chem. Commun. 2013, 49, 7501–
7503; b) J. Chen, Y. Sun, B. Liu, D. Liu, J. Cheng,
Chem. Commun. 2012, 48, 449–451.
[19] Phenols have been previously employed in metal-cata-
lyzed dehydrative direct arylations: a) L. Ackermann,
J. Pospech, H. K. Potukuchi, Org. Lett. 2012, 14, 2146–
2149; b) L. Ackermann, M. Mulzer, Org. Lett. 2008, 10,
5043–5045.
[26] M. Min, Y. Kim, S. Hong, Chem. Commun. 2013, 49,
196–198.
[27] W. Chen, P. Li, T. Miao, L.-G. Meng, L. Wang, Org.
Biomol. Chem. 2013, 11, 420–424, and references cited
therein.
[28] a) X. Zeng, L. Ilies, E. Nakamura, J. Am. Chem. Soc.
2011, 133, 17638–17640; b) X. Liu, X. Duan, Z. Pan, Y.
Han, Y. Liang, Synlett 2005, 1752–1754; c) Y. Amiel, J.
Org. Chem. 1971, 36, 3691–3696; d) Y. Amiel, J. Org.
Chem. 1971, 36, 3697–3702; e) Y. Amiel, Tetrahedron
Lett. 1971, 12, 661–663.
[20] I. Kostova, Curr. Med. Chem. – Anti-cancer Agents
2005, 5, 29–46.
[21] F. Jafarpour, S. Rahiminejadan, H. Hazrati, J. Org.
[29] C. Mhiri, F. Ladhar, R. El Gharbi, Y. Le Bigot, Synth.
Chem. 2010, 75, 3109–3112.
Commun. 1999, 29, 1451–1461.
3412
asc.wiley-vch.de
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2013, 355, 3407 – 3412