Recyclable Pd(II)complex catalyzed oxidative sp2C[sbnd]H bond acylation of 2-aryl pyridines with toluene derivatives

Article abstract of DOI:10.1016/j.jorganchem.2016.08.028

A recyclable polymer–anchored Pd(II) complex C was synthesized and characterized using different spectroscopic techniques. In addition the catalytic efficiency of the Pd (II) complex C was evaluated for ortho-acylation of 2-aryl pyridines with toluene derivatives to form aryl ketones via cross dehydrogenative coupling. In this catalytic process toluene acts as an effective coupling partner upon sp³C[sbnd]H bond oxidation for sp²C[sbnd]H bond acylation of 2-aryl pyridines in the presence of Pd(II)/TBHP system on water. Furthermore, the catalyst C was highly stable and could be easily recovered and reused for four cycles with no significant decrease in its activity and selectivity.

Full text of DOI:10.1016/j.jorganchem.2016.08.028

Journal of Organometallic Chemistry 822 (2016) 189e195
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Journal of Organometallic Chemistry
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Recyclable Pd(II)complex catalyzed oxidative sp2 CeH bond acylation
of 2-aryl pyridines with toluene derivatives
,
Pullaiah C. Perumgani a, Sai Prathima Parvathaneni a *, Srinivas Keesara b,
,
**
Mohan Rao Mandapati a
a Catalysis Laboratory, Inorganic and Physical Chemistry Division, CSIR-Indian Institute of Chemical Technology (IICT), Tarnaka, Hyderabad 500 607, India
b School of Chemistry, University of Hyderabad, Hyderabad 500046, India
a r t i c l e i n f o
a b s t r a c t
Article history:
A recyclable polymereanchored Pd(II) complex C was synthesized and characterized using different
spectroscopic techniques. In addition the catalytic efficiency of the Pd (II) complex C was evaluated for
ortho-acylation of 2-aryl pyridines with toluene derivatives to form aryl ketones via cross dehydrogen-
ative coupling. In this catalytic process toluene acts as an effective coupling partner upon sp3 CeH bond
oxidation for sp2 CeH bond acylation of 2-aryl pyridines in the presence of Pd(II)/TBHP system on water.
Furthermore, the catalyst C was highly stable and could be easily recovered and reused for four cycles
with no significant decrease in its activity and selectivity.
Received 28 June 2016
Received in revised form
24 August 2016
Accepted 25 August 2016
Available online 31 August 2016
Keywords:
Polymer-anchored Pd(II) complex C
Ortho-acylation
© 2016 Elsevier B.V. All rights reserved.
2-Aryl pyridines
Cross dehydrogenative coupling
Toulene
TBHP
1. Introduction
the use of excess Lewis acids. Further the use of expensive ruthe-
nium catalyst, handling of carbon monoxide and generation of high
The direct aromatic CeH bond functionalization is one of the
most challenging and reliable strategy to construct CeC and
Ceheteroatom bonds [1]. Among the various CeH activation
techniques, the directing group assisted CeH bond activation and
dehydrogenative cross-coupling are most facile methods that has
gained considerable attention over traditional cross-coupling
methods [2]. Benzophenones constitute prominent structural mo-
tifs of top 200 most-sold pharmaceuticals that exhibit broad
spectrum of biological activities including cholesterol regulation(-
Tricor), anti-inflammatory effects (Sector), and selective estrogen
receptor modulation (Evista) [3]. Several methods for the intro-
duction of a carbonyl moiety have been developed, including the
traditional FriedeleCrafts acylation, the coupling of aryl com-
pounds with aliphatic olefins and carbon monoxide in presence of
Ru has been generally employed [4]. These methods however
showed poor selectivity and formation of waste materials due to
reaction temperature suggests that new sustainable methods are
highly desirable.
In order to solve the selectivity issue, direct transformations
such as arylation, olefination, halogenation, and amination with the
assistance of conventional directing groups like pyridines, amides,
esters, imines, ketones, oxazolines, and nitriles have been reported
[5]. In contrast carbonylative CeH bond functionalizations (acyla-
tion) have been investigated to a lesser extent. Transition metal
catalyzed CeH activation of arenes has been achieved mostly by
employing palladium, ruthenium, rhodium, copper and Iron cata-
lysts [6]. To the best of our knowledge aldehydes, alcohols, a-oxo-
carboxylic acids, arylmethyl amines, carboxylic acids, diketones,
benzylic ethers and CO with PhI as acyl sources for transition-
metal-catalyzed carbonylative coupling reactions of directed
group assisted arene CeH bonds have been described [7]. Among
them, the catalytic cycle between Pd(II) and Pd(IV) is one of the
major pathways [8], in which a number of oxidants such as K2S2O8,
TBHP, BQ, DDQ, PIDA have been widely employed. Organic reactions
conceded ‘On-water’ have become one of the most intriguing area
of research in green chemistry as it is universal medium for all
chemical reactions of life [9]. The pioneering work for rate
* Corresponding author.
** Corresponding author.
E-mail addresses: saiprathimaiict@gmail.com (S.P. Parvathaneni), mandapati@
iict.res.in (M.R. Mandapati).
http://dx.doi.org/10.1016/j.jorganchem.2016.08.028
0022-328X/© 2016 Elsevier B.V. All rights reserved.

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P.C. Perumgani et al. / Journal of Organometallic Chemistry 822 (2016) 189e195
enhancements “on water” was first demonstrated by Breslow and
Sharpless inspired the intense research “on water” catalysis [10].
Design and development of efficient catalytic processes with en-
ergy minimization, replacement of toxic catalysts and hazardous
solvents with relatively benign solvents such as water, catalyst-free
synthesis, and high atom economy are some of the most essential
components of an ideal green synthesis [11].
Despite great achievements in green catalysis, most of the
organic transformations are incompatible with water since most of
the organic compounds do not dissolve in water while solubility is
generally considered a prerequisite for reactivity. This tends to be
an important challenge and emerging as an attractive area of
research for organic chemists.
Herein, we report the synthesis and characterization of a new
polymer supported furan-2-ylmethanamine derived palladium(II)
complex (PS-FMAePd) as an effective and highly reusable catalyst
for the synthesis of benzophenone derivatives from toluene de-
rivatives and TBHP as the oxidant under on-water conditions. Thus,
the synthesized polymer-anchored Pd(II) catalyst showed efficient
catalytic application towards a carbonylation reaction in a green
pathway without employing carbon monoxide or base or solvent
under phosphine free conditions.
2. Experimental
2.1. Material and instruments
Polystyrene is one of the most commonly employed reliable
polymeric support due to its low cost, ready availability and
chemical inertness in recent years. A variety of polymer-supported
metal catalysts for the CeC coupling reactions were reported [12].
In terms of green and environmental perspective cross dehy-
drogenative coupling, commercially available alkyl benzenes as
acylating agents is considered as ideal, eco-economical protocol.
Carbon-carbon bond formation via CeH activation in water is
another potential clean process that can have both high atom ef-
ficiency and easy recycling of the catalyst.
Recently, palladium-catalyzed oxidative ortho-acylation of
inactive C(sp2)ꢀH bonds via CeH, CeC, and CeO bond cleavage of
toluenes was reported for the synthesis of aromatic ketones [13].
In view of minimizing the waste/side product formation the use
of toxic gaseous carbon monoxide and homogeneous Pd catalyst
stands as hindrance for economical and sustainable chemistry for
the reported methods. In all the above-mentioned procedures for
ortho-acylation reactions, the Pd catalysts used are homogeneous
in nature and suffer from several drawbacks, such as they may
easily be destroyed during the course of the reaction [14]. So, the
catalysts are not easily separable from reaction mixtures and they
are non-recyclable. In order to overcome the problems associated
with homogeneous catalysts and with the growing demand for
sustainable synthesis the direct catalytic CeH functionalization
under mild reaction conditions becomes highly essential. More
Recently homogeneous conditions were replaced with supported
palladium nanoparticles in ortho-directed CDC reactions of alkyl
benzenes [15]. The main advantage of the given polymeric complex
of palladium (II) C over palladium (0) nanoparticles catalyst is
mainly in twice less loading and better recyclability.
Analytical-grade reagents and freshly distilled solvents were
used throughout the experiment. The reagents were supplied by
Sigma-Aldrich Chemicals Company, USA and Merck Co. Liquid
substrates were redistilled and dried with appropriate molecular
sieves. Distillation and purification of the solvents and substrates
were done by standard procedures.16 The starting materials and
reagents were purchased from various commercial sources and
used without further purification. ACME silica gel (60e120 mesh)
was used for column chromatography. Analytical thin-layer chro-
matography (TLC) was performed on pre-coated TLC plates with
silica gel 60-F254 plates and visualized by UV-light. 1H NMR and 13
C
NMR spectra were recorded, using tetramethylsilane (TMS) in the
solvent of CDCl3 as the internal standard on a 400, 500 MHz
spectrometer (1H NMR: TMS at 0.00 ppm, CDCl3 at 7.26 ppm; 13C
NMR: CDCl3 at 77.00 ppm). Chemical shifts (d) were recorded in
ppm with respect to TMS as an internal standard and coupling
constants are quoted in Hertz (Hz). Mass spectra were recorded on
a mass spectrometer by the electron spray ionization (ESI) and the
data acquired in positive ionization mode. HRMS spectra were
determined on TOF type mass analyzer. FTIR spectra of the samples
were recorded on a Perkin-Elmer FTIR 783 spectrophotometer us-
ing KBr pellets. A EXSTAR TG/DTA7200 instrument was used for the
thermogravimetric (TGA) analysis. Powder X-ray diffraction pat-
terns of the pure functionalized materials were recorded on a
Bruker D-8 Advance diffractometer operated at 40 kV voltage and
40 mA current using a Cu tube (
l
¼ 0.15406 nm) as the radiation
source. TEM analysis was carried out by using a JEOL 2010 TEM
operated at 200 kV. The metal content in the catalyst was deter-
mined using a Varian AA240 atomic absorption spectrophotometer
(AAS).
We mainly focused on developing simple, economical, green
pathway for carbonylation reaction/ortho-acylation of 2-
phenylpyridine. In view of continuous interest to develop simple
recyclable polymer bound metal complexes [16], herein we report a
facile synthesis of benzophenone derivatives by Pd-catalyzed
acylation of 2-phenyl pyridines by employing toluene derivatives
as the simple coupling partners. However, ortho-acylation product
was obtained in excellent yields with recyclable, heterogeneous
Palladium complex under on-water conditions with toluene as an
acylating partner (Scheme 1). This protocol is highly appreciable
due to being atom and step economic for the direct conversion of
CeH bonds to CeC bonds for aryl ketone synthesis.
2.1.1. Synthesis of the catalyst
Preparation of polymer-supported furan-2-ylmethanamine (B)
(PS-FMA): A 250 mL round-bottomflask equipped with a magnetic
stirrer was charged with CH3CN (100 mL). To this 1% DVB-
crosslinked chloromethylated polystyrene (0.5 g, 2.25 mmol/Cl),
furan-2-ylmethanamine A (2.3 mL, 22.5 mmol), and NaI (14.9 mg,
0.1 mmol) were added and the mixture was refluxed for 48 h. The
mixture was filtered and the residue was washed sequentially with
CH3CN (3 ꢁ 20 mL), 1:1 CH3OHe1M aq K2CO3 (3 ꢁ 20 mL), 1:1
CH3OHeH2O (3 ꢁ 20 mL), and Et2O (3 ꢁ 10 mL), and then dried in
an oven.
2.1.2. Preparation of polystyrene-supported Pd(II) complex (C) (PS-
FMA-Pd)
To the polystyrene-supported furan-2-ylmethanamine B (0.5 g),
EtOH (100 mL) was added and kept for 30 min. A solution of
Pd(CH3CN)2Cl2 (0.5 g) in EtOH (10 mL) was then added, and the
(1:1) mixture was refluxed for 12 h. The polymer-anchored brown
colored metal complex, impregnated with the metal, was filtered,
washed thoroughly with EtOH (3 ꢁ 30 mL), and finally dried in
Scheme 1. Palladium-catalyzed direct ortho-acylation of arenes. DG ¼ directing group.

P.C. Perumgani et al. / Journal of Organometallic Chemistry 822 (2016) 189e195
191
vacuum at 70 ꢂC for 24 h (Scheme 2).
2.1.3. General procedure for carbonylation catalyzed by polymer
anchored-Pd(II) C
A dried round bottomed flask equipped with a magnetic stir bar
was charged with 25 mg Polymer anchored-Pd(II) C catalyst (PS-
FMA-Pd), 2-phenyl pyridine (0.5 mmol), toluene (1.0 mmol), TBHP
(2.0 mmol) and water (0.5 mL) were added to a reaction vessel. The
mixture was stirred at 110 ꢂC for 24 h, then cooled to room tem-
perature and catalyst was filtered, the filtrate was extracted with
ethyl acetate (3 ꢁ 10 mL). The combined organic layers were
extracted with water, and dried over anhydrous Na2SO4. The
organic layers were evaporated under reduced pressure and the
resulting crude product was purified by column chromatography
by using ethyl acetate/hexane(1:4) as eluent to give the corre-
sponding ortho-acylation products. The products were character-
ized by 1H NMR, 13C NMR and HRMS.
3. Results and discussion
3.1. Synthesis and characterization of the polymer supported Pd(II)
catalyst C
The new polymer supported Pd(II) catalyst C was prepared in
two steps according to the reported procedure [16]. Complex C was
fully characterized by chemical analysis, SEM-EDX, TGA, AAS and IR
spectroscopic techniques. The complexation ratio of palladium to
PS-FMA is 1:1. The exact palladium content of the heterogeneous
catalyst was determined by atomic absorption spectroscopy (AAS)
suggests 5.33% of metal per gram. The coordination of palladium
metal on polymer supported ligand was confirmed by FT-IR spectra.
We observed a sharp peak at 1263 cmꢀ1 in chloromethylated
polystyrene IR spectrum, which corresponding to CeCl group. This
peak was practically eliminated after the introduction of furan-2-
ylmethanamine, and palladium onto the polymer. The decreasing
IR value of the NH group (from 3448 cm to 1 to 3423 cme1) in
polystyrene-supported ligand to complex is indicating the forma-
tion of PdeN bond.
Fig. 1. SEM images of the polymer anchored ligand PS-FMA (A) and PS-FMAePd (B)
complex.
Scanning electron micrographs were reported for PS-FMA
ligand and the supported PS-FMAePd catalyst to study the
morphological changes. The SEM images of the polymer supported
ligand and Pd(II) catalyst clearly showed the morphological change
on the surface of polystyrene after loading of metal on it (Fig. 1).
An energy dispersive spectroscopy analysis of X-rays (EDX) data
for the PS-FMA and PS-FMAePd catalyst is given in Fig. 2 (A, B). The
EDX data also inform that the attachment of palladium metal on the
surface of the polymer matrix. The EDX image of the PS-FMAePd
complex (Fig. 2B) confirms the presence of the respective atoms: C,
N, O, Cl and Pd.
3.2. Catalytic activity
Thermal stability of the complex was investigated using ther-
mogravimetric analysis (TGA) at a heating rate of 10 ꢂC min-1 over a
temperature range of 30e500 ꢂC. The TGA curve of the polymer
anchored catalyst is shown in Fig. 3. The initial sharp weight loss up
to 150 ꢂC may be due to the pore occupancy by solvent molecules
and moistures. The complex C is stable up to 330 ꢂC and thermal
decomposition of the catalyst starts above this temperature. Ther-
mogravimetric study of the complex C suggests that the polymer
anchored catalyst is very useful for high temperature reactions.
As polymer anchored metal complexes exhibit efficient catalytic
activity with broad applicability they have been extensively studied
and reported in the literature. In our previous reports we have
studied their catalytic activity in the field of coupling reactions [15].
Now we decided to investigate the catalytic activity of the PS-
FMAePd catalyst to prepare benzophenones via the carbonylation
reaction with toulenes without using carbon monoxide.
Initial experiments were carried out using 2-phenylpyridine 1a
as a model substrate, Toulene 2a as acyl coupling partner with Pd
(II) complex C and water as solvent. Different oxidants such as
H2O2, K2S2O8, O2, tert-butyl hydroperoxide (TBHP), tert-butyl
Scheme 2. Synthesis of polymer-bound furan-2-ylmethanamine derived Pd(II)
complex.

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P.C. Perumgani et al. / Journal of Organometallic Chemistry 822 (2016) 189e195
Fig. 2. EDX image of the polymer anchored ligand PS-FMA (A), polymer anchored complex PS-FMAePd(B).
Table 1
Screening of reaction conditions.a
Entry
Oxidant
Temp (ꢂC)
Time (h)
Yield (%)b
1
2
3
4
5
6
7
8
H2O2
K2S2O8
O2 (1 atm)
TBHP
TBPB
TBHP
TBHP
TBHP
TBHP
TBHP
e
110
110
110
110
110
RT
24
24
24
24
24
24
24
24
12
48
24
24
24
10
e
e
88
e
e
80
50
86
61
86
ec
ed
80e
130
110
110
110
110
110
9
10
11
12
13
TBHP
TBHP
Fig. 3. TGA curve of a Polymer anchored Pd(II) catalyst.
a
Reaction conditions: 1a (0.5 mmol), 2a (1.0 mmol), catalyst (25 mg), oxidant
peroxybenzoate (TBPB) were screened under various temperatures
as shown in Table 1. However with oxidants such as H2O2, K2S2O8,
O2, tert-butyl peroxybenzoate (TBPB) the desired product was not
obtained even at 110 ꢂC for 24 h (entries 1e3 and 5). To our delight,
tert-butyl hydroperoxide (TBHP) proved to be the best oxidant at
110 ꢂC for about 24 h and 2-phenylpyridine was obtained in 88%
yield in the presence of Pd complex C (entry 4). But TBHP was
ineffective at room temperature with no yield (entry 6) and low
yield at 80 ꢂC (entry 7). There was no considerable change in yields
by increasing the temperature from 110 ꢂC to 130 ꢂC and reaction
time from 24 to 48 h (entry 8 and 10). Notably lowering the reaction
time from 24 to 12 h resulted only in 60% yield (entry 9). As ex-
pected the desired product was not obtained even in trace amounts
in absence of oxidant, TBHP and catalyst, Pd complex C (entries
11e12). But gave good yield of the desired product in 80% even in
absence of solvent (entry 13). To know the applicability of the
catalyst under various solvent conditions the reaction was carried
with different solvents such as DMSO, EtOH, THF, CH3CN and CHCl3.
Among them EtOH, DMSO, CH3CN gave the desired products 68%,
64% and 54% yields within 24 h, where as CHCl3 and THF took 48 h
as shown in Table 2. The above optimization studies shows TBHP at
110 ꢂC on-water, in presence of Pd complex C for 24 h gave the
desired product 3a in 88% yield (entry 4, Table 1).
(2.0 mmol), water (0.5 mL), air, 24 h.
b
Isolated yield.
No oxidant.
No catalyst.
No solvent.
c
d
e
Table 2
Screening of solvents.a
Entry
Oxidant
Solvent
Time (h)
Yield (%)b
1
2
3
4
5
TBHP
TBHP
TBHP
TBHP
TBHP
DMSO
EtOH
THF
CH3CN
CHCl3
24
24
48
24
48
64
68
10
54
51
a
Reaction conditions: 1a (0.5 mmol), 2a (1.0 mmol), catalyst (25 mg), solvent
(0.5 mL).
b
Isolated yield.
summarized in Scheme 4. The reactions with toluene derivatives
bearing electron-donating groups and electron-withdrawing sub-
stituents at the aromatic ring proceeded to give the desired prod-
ucts in good to excellent yields (Scheme 3). There is considerable
influence on the yields for ortho, para and meta isomers of toluene
derivatives. The ortho isomers containing products delivered low
yields (3d, 3g, 3j and 3m) when compared to para or meta isomers
The direct ortho acylation of 2-phenylpyridine with toulene was
conducted under optimized reaction conditions, and the results are

P.C. Perumgani et al. / Journal of Organometallic Chemistry 822 (2016) 189e195
193
Scheme 3. Substrate scope for acylation of 2-phenyl pyridine.
Scheme 4. Scope for acylation of substituted 2-Phenyl pyridines.
due to steric hindrance (3b, 3f, 3l and 3c, 3e, 3h, 3k). However
electron-donating groups substituted toluene products (OMe, CH3)
gave better yields than electron withdrawing substituents (F, Cl and
Br). The OMe substituted para, meta, ortho gave (3l) 86%, (3k) 84%,
(3j) 82% and Me substituted meta, ortho resulted in (3h) 82%, (3g)
80% yields of the desired products. In case of chloro substituted
para, meta, ortho the desired product was achieved in (3b) 81%, (3c)
78%, (3d) 76% and fluoro substituted para, meta with (3f) 78%, (3e)
75%, where as meta substituted bromo gave (3m) 72% respectively.
The most interesting result is that AreBr (3m), group tolerated
since Pd species might be expected to cleave CeBr bonds easily.
Notably disubstituted methyl and napthyl substituted toluene
derivatives (3i) and (3n) gave 79% and 92% yields of acylated
products.
In addition, the directed aroylation of 2-arylpyridine with a set
of substituted aryl pyridines was performed under the optimized
reaction conditions, and the results are presented in Scheme 4. The
functional groups including methyl, methoxy, ethoxy and naphthyl
were compatible and the desired products were achieved in
excellent yields. For example, substituted aryl pyridines with 4-
methyl, ethoxy, methoxy (which bears a strong electron-donating
group) afforded the desired products 4a, 4b and 4c in 89%, 92%
and 91% respectively. Whereas 4d, 4e were obtained in 85% and 84%
and 4f in a yield of 92% yield. Thus the aroylation reaction

194
P.C. Perumgani et al. / Journal of Organometallic Chemistry 822 (2016) 189e195
selectively gave the monoacylated products with variety of 2-
phenyl pyridines.
The recyclability of the polymereanchored Pd(II) complex C was
tested in the aroylation of 2-phenyl pyridine 1a and toluene 2a. As
shown in Fig. 4, the catalyst can be reused for five cycles with only
5% decline of activity after the 5th recycle. The leaching of palla-
dium from the polymer anchored palladium(II) complex C was
confirmed by carrying out an (EDX, IR and AAS) analysis of the used
catalyst as well as the product mixtures. The analytical data of used
catalyst did not show appreciable loss in the palladium content as
compared to the fresh catalyst. The EDX and IR spectrum of the
recycled catalyst was relatively similar to that of the fresh sample,
representing the heterogeneity nature of this complex. The metal
content of the recycled catalyst was determined with the help of
AAS and it was found that there is no considerable loss in palladium
content of the recycled catalyst.
To understand the possible reaction pathway, control experi-
ments were conducted in the presence of radical scavenger TEMPO
under solvent free conditions. It was observed that desired acyla-
tion product 3a was found in <5%, indicating the possible radical
pathway. This clearly demonstrates the dual role of TBHP as an
oxidant and a radical initiator.
However during the course of the reaction formation of benz-
aldehyde was observed that could be possibly via radical oxidation
of toluene. Basing on the reported literature [17] and from our
studies a tentative mechanism to rationalize this transformation is
clearly depicted in Scheme 5. Initially Pd(II) complex C activates the
ortho CeH bond of 2-phenyl pyridine to generate chelation-
directed CeH intermediate D, which reacts with TBHP resulting
in the formation of E. This in turn reacts with aldehyde which is
produced from the oxidation of toluene, forming the acyl inter-
mediate F. This will undergo reductive elimination followed by
rapid oxidation generates the product 3a with regeneration of the
catalyst C.
Scheme 5. Possible reaction mechanism.
conditions and excellent yields. This eco-economical conditions
makes this protocol highly valuable over the existing methods.
Acknowledgements
P. S. P gratefully acknowledge to the financial assistance pro-
vided by CSIR-Senior Research Associateship (Scientist's Pool
Scheme) CSIR-SRA (IA-27520), New Delhi and PCP (UGC-SRF),
thanks for the fellowship provided by UGC, Govt of India. We also
acknowledge director IICT for providing infrastructural facilities.
References
[1] (a) C.S. Yeung, V.M. Dong, Chem. Rev. 111 (2011) 1215;
ꢀ
(b) M.M. Diaz-Requejo, P.J. Perez, Chem. Rev. 108 (2008) 3379;
4. Conclusion
(c) P. Muller, C. Fruit, Chem. Rev. 103 (2003) 2905;
(d) T. Naota, H. Takaya, S.I. Murahashi, Chem. Rev. 98 (1998) 2599;
(e) L. Ackermann, R. Vicente, A.R. Kapdi, Angew. Chem. Int. Ed. 48 (2009)
9792;
In summary, we have described an efficient aroylation reaction
of 2-phenyl pyridines with toluene derivatives as acylating partners
under “on water” conditions. The simple Polymer anchored Pd(II)
complex was synthesized and found to be active for selective
acylation of ortho-directed CDC reaction of 2-phenyl pyridines with
toluene derivatives affording diverse range of aromatic ketones in
high yields. This heterogeneous catalyst is stable and can be reused
for five cycles without appreciable loss of activity, indicating
effective anchoring of the polymer. All the reactions were carried
out without any solvent, recyclable Pd complex, TBHP as oxidant
with broad substrate scope, low metal loadings, on-water
(f) L. Ackermann, Chem. Commun. 46 (2010) 4866.
[2] (a) J.J. Mousseau, A.B. Charette, Acc. Chem. Res. 46 (2013) 412;
(b) D.A. Colby, R.G. Bergman, J.A. Ellman, Chem. Rev. 110 (2010) 624;
(c) O. Daugulis, H.Q. Do, D. Shabashov, Acc. Chem. Res. 42 (2009) 1074;
(d) J.A. Ashenhurst, Chem. Soc. Rev. 39 (2010) 540;
(e) C.J. Scheuermann, Chem. Asian J. 5 (2010) 436.
[3] (a) McGrath, M. Brichacek, J.T. Njardarson, J. Chem. Educ. 87 (2010) 1348;
(b) S. Gmouh, H. Yang, M. Vaultier, Org. Lett. 5 (2003) 2219.
[4] (a) H. Heaney, in: B.M. Trost, I. Fleming (Eds.), Comprehensive Organic Syn-
thesis, vol. 2, Pergamon Press, Oxford, 1991, p. 733;
(b) G.A. Olah, Friedelecrafts and Related Reactions, Wiley-Interscience, New
York, 1963;
(c) E.J. Moore, W.R. Pretzer, T.J. O'Connell, J. Harris, L. La-Bounty, L. Chou,
S.S. Grimmer, J. Am. Chem. Soc. 114 (1992) 5888;
(d) N. Chatani, T. Fukuyama, F. Kakiuchi, S. Murai, J. Am. Chem. Soc. 118 (1996)
493;
(e) T. Fukuyama, N. Chatani, F. Kakiuchi, S. Murai, J. Org. Chem. 62 (1997)
5647;
(f) N. Chatani, Y. Ie, F. Kakiuchi, S. Murai, J. Org. Chem. 62 (1997) 2604;
(g) Y. Ie, N. Chatani, T. Ogo, D.R. Marshall, T. Fukuyama, F. Kakiuchi, S. Murai,
J. Org. Chem. 65 (2000) 1475.
[5] (a) P. Gandeepan, K. Parthasarathy, C.H. Cheng, J. Am. Chem. Soc. 132 (2010)
8569;
(b) T. Nishikata, A.R. Abela, S.L. Huang, B.H. Lipshutz, J. Am. Chem. Soc. 132
(2010) 4978;
(c) F.W. Patureau, F. Glorius, J. Am. Chem. Soc. 132 (2010) 9982;
(d) J. Wen, S. Qin, L.F. Ma, L. Dong, J. Zhang, S.S. Liu, Y.S. Duan, S.Y. Chen,
C.W. Hu, X.Q. Yu, Org. Lett. 12 (2010) 2694;
(e) B. Tang, R. Song, C. Wu, Y. Liu, M. Zhou, W. Wei, G. Deng, D. Yin, J.H. Li,
J. Am. Chem. Soc. 132 (2010) 8900;
(f) T. Nishikata, B.H. Lipshutz, Org. Lett. 12 (2010) 1972;
(g) X. Chen, K.M. Engle, D.H. Wang, J.Q. Yu, Angew. Chem. Int. Ed. 48 (2009)
5094;
Fig. 4. Recyclability of the Polymer anchored Pd(II) complex C.
(h) Y.H. Zhang, J.Q. Feng, C.J. Li, J. Am. Chem. Soc. 130 (2008) 2900;

P.C. Perumgani et al. / Journal of Organometallic Chemistry 822 (2016) 189e195
195
(i) L.V. Desai, K.J. Stowers, M.S. Sanford, J. Am. Chem. Soc. 130 (2008) 13285;
Ed. 52 (2013) 6293.
(j) G.W. Wang, T.T. Yuan, X.L. Wu, J. Org. Chem. 73 (2008) 4717;
(k) G.J. Deng, L. Zhao, C.J. Li, Angew. Chem. Int. Ed. 47 (2008) 6278;
(l) A.S. Tsai, R.G. Bergman, J.A. Ellman, J. Am. Chem. Soc. 130 (2008) 6316;
(m) X. Chen, X.S. Hao, C.E. Goodhue, J.Q. Yu, J. Am. Chem. Soc. 128 (2006)
6790;
(n) X.B. Wan, Z.X. Ma, B.J. Li, K.Y. Zhang, S.K. Cao, S.W. Zhang, Z.J. Shi, J. Am.
Chem. Soc. 128 (2006) 7416;
(o) H.Y. Thu, W.Y. Yu, C.M. Che, J. Am. Chem. Soc. 128 (2006) 9048;
(p) K. Dipannita, N.R. Deprez, L.V. Deprez, M.S. Sanford, J. Am. Chem. Soc. 127
(2005) 7330.
[8] (a) A.B. Weinstein, S.S. Stahl, Catal. Sci. Technol. 4 (2014) 4301;
(b) K.J. Stowers, A. Kubota, M.S. Sanford, Chem. Sci. 3 (2012) 3192.
[9] (a) T. Head-Gordon, G. Hura, Chem. Rev. 102 (2002) 2651;
(b) U.M. Lindstrom, Chem. Rev. 102 (2002) 2751;
(c) Y. Hayashi, Angew. Chem. Int. Ed. 45 (2006) 8103;
(d) J. Mlynarski, S. Bas, Chem. Soc. Rev. 43 (2014) 577.
[10] (a) R. Breslow, Acc. Chem. Res. 24 (1991) 159;
(b) R. Breslow, Acc. Chem. Res. 37 (2004) 471;
(c) S. Narayan, J. Muldoon, M.G. Finn, V.V. Fokin, H.C. Kolb, K.B. Sharpless,
Angew. Chem. Int. Ed. 44 (2005) 3275.
[6] (a) T.W. Lyons, M.S. Sanford, Chem. Rev. 110 (2010) 1147;
(b) X. Chen, K.M. Engle, D.-H. Wang, J.-Q. Yu, Angew. Chem. Int. Ed. 48 (2009)
5094;
[11] B.M. Trost, Angew. Chem. Int. Ed. 34 (1995) 259.
[12] (a) M. Bakherad, A. Keivanloo, B. Bahramian, S. Jajarmi, J. Organomet. Chem.
724 (2013) 206;
(c) S. Murai, F. Kakiuchi, S. Sekine, Y. Tanaka, A. Kamatani, M. Sonoda,
N. Chatani, Nature 366 (1993) 529;
(b) Y. He, C. Cai, J. Organomet. Chem. 696 (2011) 2689;
(c) S.M. Islam, P. Mondal, A.S. Roy, S. Mondal, D. Hossain, Tetrahedron Lett. 51
(2010) 2067.
(d) D.A. Colby, R.G. Bergman, J.A. Ellman, Chem. Rev. 110 (2010) 624;
(e) C. He, S. Gou, L. Huang, A. Lei, J. Am. Chem. Soc. 132 (2010) 8273;
(f) M. Sai, H. Yorimitsu, K. Oshima, Angew. Chem. Int. Ed. 50 (2011) 3294;
(g) C.L. Sun, B.J. Li, Z.J. Shi, Chem. Rev. 111 (2011) 1293;
(h) N. Xu, P. Li, Z. Xie, L. Wang, Chem. Eur. J. 22 (2016) 2236;
(i) J.P. Yao, G.W. Wang, Tetrahedron Lett. 57 (2016) 1687;
(j) F.X. Xiong, C. Qian, D. Lin, W. Zeng, X. Lu, Org. Lett. 15 (2013) 5444;
(k) Z.J. Cai, C. Yang, S.Y. Wang, S.J. Ji, J. Org. Chem. 80 (2015) 7928;
(l) H. Tang, C. Qian, D. Lin, H. Jiang, W. Zeng, Adv. Synth. Catal. 356 (2014) 519.
[7] (a) X. Chen, X. Cui, Y. Wu, Org. Lett. 18 (2016) 2411;
(b) Y. Wu, L. Sun, Y. Chen, Q. Zhou, J.W. Huang, H. Miao, H.B. Luo, J. Org. Chem.
81 (2016) 1244;
[13] (a) S. Guin, S.K. Rout, A. Banerjee, S. Nandi, B.K. Patel, Org. Lett. 14 (2012)
5294;
(b) H. Song, D. Chen, C. Pi, X. Cui, Y. Wu, J. Org. Chem. 79 (2014) 2955;
(c) Y. Wu, P.Y. Choy, F. Mao, F.Y. Kwong, Chem. Commun. 49 (2013) 689;
(d) Y. Wu, L.J. Feng, X. Lu, F.Y. Kwong, H.B. Luo, Chem. Commun. 50 (2014)
15352.
[14] (a) X.F. Jia, S.H. Zhang, W.H. Wang, F. Luo, J. Cheng, Org. Lett. 11 (2009) 3120;
(b) O. Basle, J. Bidange, Q. Shuai, C.J. Li, Adv. Synth. Catal. 352 (2010) 1145;
(c) C.L. Li, L. Wang, P.H. Li, W. Zhou, Chem. Eur. J. 17 (2011) 10208;
(d) Y.X. Yang, B. Zhou, Y.C. Li, Adv. Synth. Catal. 354 (2012) 2916;
(e) C.W. Chan, Z.Y. Zhou, W.Y. Yu, Adv. Synth. Catal. 353 (2011) 2999;
(f) A.B. Paula, F.G. Areli, C. Arkaitz, M. Ruben, J. Am, Chem. Soc. 132 (2010) 466.
[15] Y.S. Bao, D. Zhang, M. Jia, B. Zhaorigetu, Green Chem. 18 (2016) 2072.
[16] (a) K. Balaswamy, P.C. Pullaiah, M.M. Rao, Appl. Catal. A General 483 (2014)
110;
(c) Y. Wu, B. Li, F. Mao, X. Li, F.Y. Kwong, Org. Lett. 13 (2011) 3258;
(d) Z.Y. Li, D.D. Li, G.W. Wang, J. Org. Chem. 78 (2013) 10414;
(e) M. Kim, J. Park, S. Sharma, A. Kim, E. Park, J.H. Kwak, Y.H. Jung, I.S. Kim,
Chem. Commun. 49 (2013) 925;
(f) P. Fang, M. Li, H. Ge, J. Am. Chem. Soc. 132 (2010) 11898;
(g) Y. Shin, S. Sharma, N.K. Mishra, S. Han, J. Paek, H. Oh, J. Ha, H. Yoo,
Y.H. Jung, I.S. Kim, Adv. Synth. Catal. 357 (2015) 594;
(h) S. Sharma, M. Kim, J. Park, M. Kim, J.H. Kwak, Y.H. Jung, J.S. Oh, Y. Lee,
I.S. Kim, Eur. J. Org. Chem. (2013) 6656;
(i) M. Kim, N.K. Mishra, J. Park, S. Han, Y. Shin, S. Sharma, Y. Lee, E.-K. Lee,
J.H. Kwak, I.S. Kim, Chem. Commun. 50 (2014) 14249;
(j) Q. Zhang, F. Yang, Y. Wu, Chem. Commun. 49 (2013) 6837;
(k) J. Lu, H. Zhang, X. Chen, H. Liu, Y. Jiang, H. Fu, Adv. Synth.Catal 355 (2013)
529;
(b) K. Balaswamy, P.C. Pullaiah, K. Srinivas, M.M. Rao, Inorg. Chim. Acta 423
(2014) 95;
(c) K. Balaswamy, P.C. Pullaiah, M.M. Rao, Appl. Organometal. Chem. 28 (2014)
756.
[17] (a) F. Xiao, Q. Shuai, F. Zhao, O. Basle, G. Deng, C.J. Lu, Org. Lett. 13 (2011)
1614;
ꢀ
(b) D.J. Cardenas, B.M. Matute, A.M. Echavarren, J. Am. Chem. Soc. 128 (2006)
5033;
(c) B. Mariampillai, J. Alliot, M.Z. Li, M.A. Lautens, J. Am. Chem. Soc. 129 (2007)
15372;
(l) W. Zhou, H. Li, L. Wang, Org. Lett. 14 (2012) 4594;
(m) S. Han, S. Sharma, J. Park, M. Kim, Y. Shin, N.K. Mishra, J.J. Bae, J.H. Kwak,
Y.H. Jung, I.S. Kim, J. Org. Chem. 79 (2014) 275;
(d) K.M. Gericke, D.I. Chai, N. Bieler, M. Lautens, Angew. Chem. Int. Ed. 121
(2009) 1447;
(e) R. Kishore, M. Lakshmi Kantam, J. Yadav, M. Sudhakar, S. Laha,
A. Venugopal, J. Mol. Catal. A Chem. 379 (2013) 313.
(n) A. Tlili, J. Schranck, J. Pospech, H. Neumann, M. Beller, Angew. Chem. Int.