Intramolecular heterocyclization and cyclopalladation of selenoanisole substituted propargyl imines: Synthesis and reactivity of Pd-C bond towards alkynes

Article abstract of DOI:10.1016/j.jorganchem.2014.01.028

The intramolecular cyclization of o-SeMeC₆H₄CCC- (CF₃)(NAr) with [PdCl₂(PhCN)₂] to dimeric cyclopalladated benzoselenophene has been developed under mild conditions. The reactivity of the new dimeric

Full text of DOI:10.1016/j.jorganchem.2014.01.028

Journal of Organometallic Chemistry 757 (2014) 14e20
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Intramolecular heterocyclization and cyclopalladation of
selenoanisole substituted propargyl imines: Synthesis and reactivity
of PdeC bond towards alkynes
a
a
a
b
Shailesh S. Racharlawar , D. Shankar , Manjusha V. Karkhelikar , B. Sridhar ,
Pravin R. Likhar
a
a,
*
Organometallic Gp., I & PC Division, Indian Institute of Chemical Technology, Hyderabad 500607, India
X-ray Crystallography Center, Indian Institute of Chemical Technology, Hyderabad 500607, India
b
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 3 December 2013
Received in revised form
The intramolecular cyclization of o-SeMeC H C^CCe(CF )(]NAr) with [PdCl (PhCN) ] to dimeric
6
4
3
2
2
cyclopalladated benzoselenophene has been developed under mild conditions. The reactivity of the new
dimeric cyclopalladated benzoselenophene is examined towards insertion of alkynes into PdeC bond.
The reactivity study is also extended to PdeC bond of dimeric cyclopalladated benzothiophenes towards
insertion of alkynes.
16 January 2014
Accepted 22 January 2014
Ó 2014 Elsevier B.V. All rights reserved.
Keywords:
Palladacycle
Alkynes
Benzoseleno[2,3-c] pyridinone
Palladium
Benzothio[2,3-c] pyridinone
1. Introduction
analogues of benzo[b]thiophenes though, have received limited
attentions in the manufacturing of pharmaceutical drugs, their
The transition metals catalysed heterocyclization of alkynes
with a nucleophile in close proximity to triple bond is a common
method for the preparation of variety of heterocycles [1e3]. The
palladium-based catalysts are one of the promising candidates to
effect this cyclization reactions. This is mainly because of the facile
redox interchange between the two stable Pd(II)/Pd(0) oxidation
states, compatible with various functional groups, easy availability,
low toxicity and relatively low cost of palladium metal [4e6]. Pyr-
roles, furans, furanones, pyrazoles, isoxazoles, indoles, indolizidi-
nones, pyrimidines, pyridinones, and quinolines are few of
the important heterocycles prepared by palladium catalysed het-
erocyclization [7e11]. Likewise, among the other heterocycles,
chalcogen based-heterocycles, benzothiophenes and benzosele-
nophenes [12e15] have attracted special attention since their core
structures are present in a great number of biologically active
compounds and functional molecules; in particular, benzo[b]thio-
phenes and thiophenes are prevalent in several compounds that
are of pharmaceutical and material interests [16e20]. Selenium
biological activities are well documented in the literature [21,22].
Substitution at 2 and 3 position of chalcogen containing hetero-
cycles are important building blocks for the preparation of potential
drugs. The transition metals (including palladium) as catalysts or
promoters in the synthesis of chalcogen (sulphur, selenium, and
tellurium) containing heterocycles are however incompatible with
functionality or lack regioselectivity [23e28] and therefore, have
rarely been employed in such cyclization reactions [29,30]. Our
research group has recently reported the simultaneous hetero-
cyclization and selective palladacyclization by the treatment of o-
SMeC
mediary cyclopalladated benzothiophene, [(C
NAr)ePd( -Cl)] via intramolecular thiopalladation [31]. The
H
6 4
C^CCe(CF
3
)(]NAr), with [PdCl
2
(PhCN)
2
] to stable inter-
8
H
4
S-3-)C(CF )(]
3
m
2
isolation of the corresponding intermediary organopalladium
compounds in the presence of potentially coordinating group has
provided a new route for the synthesis of annulated benzothio-
phene based-palladium complexes. Further, we reported the cata-
lytic activity of the new class of palladacycles in CeC bond forming
reactions [32]; for derivatization and for anti-cancer activity
[32,33]. The fact that the simultaneous heterocyclization and se-
lective palladacyclization take place under mild conditions
prompted us to develop new selenoanisole substituted alkynes for
*
Corresponding author. Tel.: þ91 40 27193510; fax: þ91 40 27160921.
E-mail address: plikhar@iict.res.in (P.R. Likhar).
0
022-328X/$ e see front matter Ó 2014 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2014.01.028

S.S. Racharlawar et al. / Journal of Organometallic Chemistry 757 (2014) 14e20
15
Scheme 1. Synthesis of selenoanisole substituted propargyl imine.
the synthesis of corresponding palladacycles and examine their
reactivity through insertion of C^C into PdeC bond of palladacycle.
The reactivity of PdeC bond of palladacycles towards alkynes has
been well studied by pioneer work of Pfeffer et al. [34e36] and
Heck et al. [37,38] However, in this paper, we report the synthesis of
cyclopalladated benzoselenophenes derived from selenoanisole
substituted propargyl imines (simultaneous formation of hetero-
cycle and metallocycle) and their reactivity with alkynes to ben-
zoseleno[2,3-c] pyridinones. The reactivity is also extended with
alkynes insertion into PdeC bond of dimeric cyclopalladated ben-
zothiophenes to benzothieno[2,3-c]pyridinones. Pyridinone fused
benzothiophenes and benzoselenophenes through insertion of
triple bond into PdeC bond of corresponding cyclopalladated het-
erocycle lead to formation of new class of multiple fused
heterocycles.
The solid palladacycle, 4c was isolated in good yield and charac-
terized by H NMR, C NMR, and IR spectroscopy. The C NMR and
1
13
13
IR spectra of 3c showed characteristic resonances of a C^C bond at
ꢁ
1
84.77 and 97.92 ppm and a stretching frequency at 2180 cm
,
respectively, which are absent upon the cyclopalladation in 4c.
1
Similarly, the H NMR spectra of 4c clearly shows the absence of a
3 3 6 4
CH signal from the o-SeCH C H group. Further, the change in
13
chemical shift from 131 ppm to 165 ppm in the C NMR of the
imine carbon atom (C]N) suggests the interaction of nitrogen with
the palladium atom. To investigate the scope of present cyclization
reaction, various palladacycles were prepared by changing the
substitutions at aromatic ring of imine. In the previous report, the
reaction of dichorobis(triphenylphosphine)palladium(II) with CF
3
substituted propargyl (phenyl)imine did not proceed to the for-
mation of desired cyclopalladated benzothiophene and surprisingly
cyclopalladation occurred only with C
F
4 9
substituted propargyl
(
phenyl)imine [31] while in preparation of palladated benzosele-
2
. Results and discussion
3
nophene, cyclopalladation with CF substituted propargyl (phenyl)
imine took place smoothly with dichorobis(triphenylphosphine)
palladium(II) to desired product(4a) in 70% yield (Scheme 2). All the
palladacycles were isolated in good yields and well characterized
In the modified preparation of ortho-selenoanisole substituted
perfluoroalkyl propargyl imines (3), 2-ethylphenyl methylselane,
1) was first prepared in quantitative yield from 2-iodophenyl
(
1
13
methylselane [39] and trimethylsillylacetylene (TMSA) using
Sonogashira protocol. The reaction of perfluoroalkyl imidoyl io-
dides, 2 with 1 afforded 3 in good yield in presence of dichor-
obis(triphenylphosphine)palladium(II) and copper iodide as co-
catalyst (Scheme 1). Various ortho-selenoanisole perfluoro prop-
argyl imines were prepared in good to moderate yields. All the
by H NMR, C NMR and IR spectroscopy.
The single crystal of 4c was obtained on slow evaporation of THF
at room temperature. The structure of 4c was ascertained by means
of X-ray diffraction. The crystallographic data of the dimeric com-
pound 4c suggest that the Pd(II) centre is coordinated in a square-
planar fashion by the N1, an imine nitrogen atom, and the C3(sp2)
vinyl carbon atom on one side and two bridging Cl atoms on other
side. The stereochemistry of the palladacycle 4c was observed as a
transoid dimeric form with the asymmetric unit containing one
half-molecule and the other half generated by a crystallographic
two-fold axis of symmetry similar to previously observed
benzothiophene-based palladacycle (Fig. 1).
1
13
propargyl imines are characterized by H NMR, C NMR, and mass
spectrometry.
The palladation of ortho-selenoanisole perfluoro propargyl im-
ines was proceeded with stoichiometric amount of dichorobis(-
ꢀ
triphenylphosphine)palladium(II) in dry THF solvent at 0 C. The
reaction was completed in 2 h and furnished air and moisture
stable bright orange solid along with small amount of intact
starting material after workup and separation by ether washing.
The possible reaction pathway for the formation of
a
benzoseleno-based palladacycle is similar to that of
Scheme 2. Cyclopalladation of selenoanisole substituted propargyl imine.

16
S.S. Racharlawar et al. / Journal of Organometallic Chemistry 757 (2014) 14e20
Palladacycles, 4a was allowed to react with DPA in different sol-
vents, temperatures and conditions. Eventually, we found that
palladacycle, 4a (0.15 mmol) in toluene reacts with excess of DPA
under refluxing condition for 12 h affords benzoseleno[2,3-c] pyr-
idinone in good yields (Scheme 4).
In order to rationale the formation of tricyclic heterocycles 6 and
7, the proposed mechanism involves generation of seven member
ring intermediate after coordination of triple bond to palladium
and subsequent insertion into PdeC bond where palladium in-
teracts with alkynyl carbon followed by heterolytic palladium-
carbon cleavage and ring closer. The generation of black palla-
dium metal is evident for the reductive elimination of palladium
during the progress of reaction. The formation of benzoseleno[2,3-
c] pyridinone rather than expected pyridinium salt may be attrib-
uted to the presence of CF
carbon. The carbon atom attached to CF
because of highly electronegative nature of CF
3
group bonded to the pyridinium ring
is more electrophilic
group which in turn
3
3
is susceptible to nucleophilic attack by hydroxyl ion and undergoes
subsequent oxidation to form carbonyl group (Scheme 5).
The most significant signal in the FT-IR in favour to formation of
carbonyl group was evidenced by the appearance of sharp peak at
Fig. 1. The molecular structure of 4c, with the atom-numbering scheme. Displacement
ellipsoids are drawn at the 30% probability level and H atoms are shown as small
spheres of arbitrary radius. Unlabelled atoms are generated by the inversion centre
ꢁ
1
ꢁ1
1645 cm (for benzoselenophene pyridinone) and 1653 cm (for
benzothiophene pyridinone). The chemical shift in 13C NMR
(
ꢁx, ꢁy, ꢁz).
3
[165.2 ppm] for the carbon attached to the CF group of pallada-
cycles was not changed much upon the insertion of C^C into PdeC
bond [160.0 ppm]. The mass of pyridinone was further confirmed
by high resolution mass spectrometry. Finally, the suitable single
crystals of 7b was developed by evaporating the chloroform solvent
at 35e40 C in four days and the structure was ascertained by
means of X-ray diffraction study (Fig. 2).
benzothiophene-based palladacycle (Scheme 3) [31]. In the pro-
posed mechanism, we speculate that first step involves the coor-
dination of the N atom followed by interaction of the triple bond to
the palladium metal. The triple bond coordinated to a Pd centre
undergoes selectively intramolecular seleno addition. In intra-
molecular nucleophilic addition, the electronically rich seleno
group attacks the activated triple bond, followed by the removal of
methyl group via S 2 nucleophilic displacement by the Cl anion
N
present in the reaction medium. The change in chemical shift of
neighbouring proton to alkyne in the aromatic ring is shifted from
ꢀ
The study on alkyne insertion into PdeC bond was then
extended to the various cyclopalladated benzoselenophenes and
benzothiophenes and the corresponding pyridinones were ob-
tained in good yields (Table 1). We have also examined the reac-
tivity of the cyclopalladated benzothiophene towards
unsymmetrical acetylene. 1-methoxy-4-(phenylethynyl)benzene
reacted smoothly with 4a to affords mixture of the corresponding
isomers, 7c/7d in a 60:40 ratio (the ratio of major to minor
7.42 to 9.42 ppm. In the benzothio-based palladacycle preparation
the chemical shift for this proton was observed at 8.42 ppm,
whereas in the present case chemical shift of the proton was
observed at 9.42 ppm.
1
regioisomer was calculated using H NMR); these isomers were
isolated and characterized without separation of single
regioisomer. Thus, the steric and electronic properties of the sub-
stituent on the phenyl ring of acetylene do not attract much
discrimination in the insertion of unsymmetrical acetylene into the
PdeC bond. While changing the perfluoro group of the benzo-
Next, we examined the reactivity of these palladacycles towards
alkynes. It has been seen that imine or amine coordinated palla-
dacycles usually undergo insertion of alkyne into PdeC bond of di-
m-chloro-bridged dimer to form quaternary ammonium halide salts
[40]. Taking into consideration the presence of imine nitrogen co-
thiophene based-palladacycle [eC
4 9
F ], we found that under set
ordinated to the palladium, we directed our efforts towards the
insertion of diphenyl acetylene (DPA) into PdeC bond.
optimized reaction condition, diphenyl acetylene undergo
Scheme 3. Plausible reaction pathway for the formation of a benzoseleno-based palladacycle.

S.S. Racharlawar et al. / Journal of Organometallic Chemistry 757 (2014) 14e20
17
Scheme 4. Alkynes insertion into PdeC bond of cyclopalladated benzoselenophene and benzothiophene.
cyclization in presence of palladacycle to afford selectively hex-
aphenylbenzene and no corresponding pyridinone product was
observed (entry 7). In case of mono substituted alkynes, (1-hexyne
and phenyl acetylene) the insertion reaction did not proceed to
desired cyclized product under set optimized reaction conditions
1
13
[
41e43]. All the products were characterized by H NMR, C NMR,
IR and mass spectrometry.
3
. Conclusion
The selective cyclopalladated benzoselenophenes are synthe-
sized from selenoanisole substituted propargyl imine ligands and
palladium salt through intramolecular cyclization under mild
conditions which otherwise requires coordinating benzoseleno-
phene ligands. The reactivity of the cyclopalladated benzoseleno-
phenes is examined towards alkynes through insertion into PdeC
bond to afford fused heterocycles, benzoseleno[2,3-c] pyridinones.
The metal-mediated synthesis of benzothieno[2,3-c] pyridinones is
Fig. 2. X-ray structure of benzothieno[2,3-c]pyridinone 7b, with the atom-numbering
scheme. Displacement ellipsoids are drawn at the 30% probability level and H atoms
are shown as small spheres of arbitrary radius. Toluene solvate omitted for clarity.
Scheme 5. Plausible reaction pathway for the insertion of alkyne into PdeC bond of palladacycle.

18
S.S. Racharlawar et al. / Journal of Organometallic Chemistry 757 (2014) 14e20
also developed by alkynes insertion into PdeC bond of cyclo-
palladated benzothiophene. The reactivity study carried out with
the new class of palladacycles reveals that cyclopalladated het-
erocycles have enormous potential for the synthesis of new class of
fused heterocycles through insertion reactions. Investigations to-
wards the catalytic use of palladium salts and photophysical
properties of these pyridinones are in progress.
chromatography was accomplished using silica gel 60e120 mesh.
Technical grade solvents were used for chromatography and
distilled prior to use. NMR spectra were recorded in Fourier
transform mode. The H, C and F NMR spectra were recorded on
a Bruker-Avance (300 MHz), Varian-Inova (400 MHz) and Varian-
1
13
19
3 3
Inova (500 MHz) spectrometers in CDCl and CFCl solvents and
1
TMS as the internal standard. Multiplicities in the H NMR spectra
are described as: s ¼ singlet, d ¼ doublet, t ¼ triplet, q ¼ quartet,
qt ¼ quintet, m ¼ multiplet, br ¼ broad; coupling constants are
reported in Hz. Infrared spectra were recorded on a Thermo Nicolet
4
. Experimental section
ꢁ1
4.1. General
Nicolet Nexus 670 spectrometer and reported in cm . Low (MS)
and high resolution mass spectra (HRMS) were recorded on a
Waters 2695 and Thermo Scientific Exactive spectrometer respec-
tively and mass/charge (m/z) ratios are reported as values in atomic
mass units. Melting points were recorded on a Toshniwal melting
point apparatus.
All the reactions were carried out in oven dried glassware under
an atmosphere of nitrogen. Chemicals were purchased from Aldrich
and used as it is unless mentioned otherwise. All the solvents used
for reactions were dried before use. Product purification by column
Table 1
Alkynes insertion into PdeC bond of cyclopalladated benzoselenophenes and benzothiophenes.
Palladacycles Product
Yields of isolated product (%)
6
6
1
7
7
6
7
1
9
8
75
0

S.S. Racharlawar et al. / Journal of Organometallic Chemistry 757 (2014) 14e20
19
4
.2. Typical procedure for the preparation of N-aryl perfluoroalkyl
4.3.2. [(C
8 4 6 4 3 2
H Se-3-)C(]NeC H -o-OMe)(CF )Pd(m-Cl)] (4b)
1
propargyl imines
Yield: 82% (107 mg), orange solid. H NMR (300 MHz, DMSO-d )
6
3
3
d
¼ 9.47 (d, JHH ¼ 7.7 Hz, 1H), 8.11 (d, JHH ¼ 7.4 Hz, 1H), 7.48e7.31
3 3
To a stirred mixture of [PdCl
2
(PPh
3
)
2
] (2 mol%), CuI (4 mol%) in
(m, 3H), 7.22 (d, JHH ¼ 7.6 Hz, 1H), 7.13 (d, JHH ¼ 8.1 Hz, 1H), 7.0 (t,
3
13
Et
3
N (4 mL), alkyne (1 mmol) and N-aryl perfluoroalkyl imidoyl
atmosphere.
J
HH ¼ 7.6 Hz, 1H), 3.86 (s, 3H). C NMR (75 MHz, DMSO-d
6
)
iodide (1 mmol) were added successively under N
2
d 165.49, 151.84, 145.85, 144.14, 133.3, 132.67, 130.88, 128.59, 128.0,
2
The mixture was stirred at room temperature until the starting
materials were consumed. The reaction mixture was filtered and
solvent was removed from filtrate under reduced pressure. The
crude product obtained was purified by column chromatography
using hexane-ethyl acetate mixture(95:5).
125.58, 124.77, 124.19, 119.63, 117.32 (q, JCF ¼ 283 Hz) 111.41, 55.84.
19
F NMR (376 MHz, DMSO-d
6
):
Elemental analysis: Anal. Calcd. for
: C, 39.03; H, 2.12; N, 2.68. Found: C, 39.12;
d
ꢁ60.62 (s, 3F). IR (KBr): 1561, 1445,
ꢁ
1
1160, 753 cm
Pd
.
C
34
H22Cl
2
6
F N
2
O
2
2
Se
2
H, 2.05; N, 2.73.
4
.2.1. Methyl(2-(4-phenyl-3-(trifluoromethyl)but-3-en-1-ynyl)
4.3.3. [(C
Yield: 85% (111 mg), orange solid. H NMR (300 MHz, DMSO-d
9.50e9.41 (m,1H), 7.94e7.84 (m,1H), 7.40e7.31 (m, 2H), 7.16e7.07
8 4 6 4 3 2
H Se-3-)C(]NeC H -p-OMe)(CF )Pd(m-Cl)] (4c)
1
phenyl)selane (3a)
6
)
Yield: 82% (301 mg), yellow solid, mp 82e84 C. 1H NMR
ꢀ
d
3
13
(
500 MHz, CDCl
3
)
d
7.41 (t, JHH ¼ 7.7 Hz, 2H), 7.36e7.30 (m, 3H),
(m, 2H), 6.95e6.85 (m, 2H), 3.82 (s, 3H). C NMR (75 MHz,
DMSO-d 55.31, 113.22, 119.05, 124.67, 125.47, 127.84,
131.09, 132.57, 137.45, 144.0, 145.74, 158.16, 165.20 ppm. F NMR
(376 MHz, DMSO-d ):
ꢁ58.22 (s, 3F). IR (KBr): 1552, 1501, 1444,
1251, 1153, 838 cm . Elemental analysis: Anal. Calcd. for
Pd Se : C, 39.03; H, 2.12; N, 2.68. Found: C, 38.95;
13
7
.30e7.23 (m, 3H), 7.14e7.10 (m,1H), 2.28 (s, 3H). C NMR (75 MHz,
CDCl 147.52, 138.36, 134.20, 131.19, 128.93, 128.51, 128.25, 127.41,
25.42, 121.39, 120.59, 116.90, 98.14, 83.93, 6.49 ppm. F NMR
376 MHz, CDCl ):
ꢁ71.38 (s, 3F). IR (KBr): 2187, 1265, 1145, 1070,
040, 800, 759, 693 cm . HRMS: Anal. Calcd. for C17
6
)
d
19
3
) d
19
1
(
1
3
6
d
ꢁ
1
3
d
ꢁ1
H13NF
3
Se:
C
34
H22Cl
2
6
F N
2
O
2
2
2
68.01598. Found: 368.01692.
H, 2.17; N, 2.59.
4.2.2. (2-(4-(2-Methoxyphenyl)-3-(trifluoromethyl)but-3-en-1-
4.4. Typical procedure for the synthesis of pyridinone
ynyl)phenyl)(methyl)selane (3b)
Yield: 87% (346 mg), yellow liquid. H NMR (300 MHz, CDCl
7.32e7.25 (m, 3H), 7.23e7.14 (m, 2H), 7.13e7.06 (m, 1H), 6.99e
1
3
)
A mixture of the palladacycle 4/5 (0.15 mmol) and diaryl alkyne
(1.5 mmol) was refluxed in toluene (15 mL) for 12 h. The resulting
mixture was cooled to room temperature and solvent was evapo-
rated under reduced pressure. The residue obtained was dissolved
in DCM (25 mL). The palladium black formed was removed by
filtration and the filtrate was concentrated and subjected to column
chromatography using neutral alumina and DCM/hexane (50/50) to
yield solid product 6/7.
d
6
d
1
3
.91 (m, 2H), 3.85 (s, 3H), 2.25 (s, 3H). C NMR (75 MHz, CDCl
149.89, 137.55, 136.53, 133.44, 130.41, 127.54, 127.48, 124.76,
20.17, 119.98, 119.90, 116.34, 111.31, 97.72, 84.04, 56.03, 7.25 ppm.
3
)
1
1
9
F NMR (376 MHz, CDCl
144, 1034, 802, 750, 553 cm . HRMS: Anal. Calcd. for C18H15ON-
3
):
d
ꢁ71.16 (s, 3F). IR (KBr): 2189, 1126,
ꢁ
1
1
F
3
Se: 398.0265. Found: 398.02759.
4.2.3. (2-(4-(4-Methoxyphenyl)-3-(trifluoromethyl)but-3-en-1-
4.4.1. 2,3,4-Triphenylbenzo[4,5]selenopheno[2,3-c]pyridin-1(2H)-
ynyl)phenyl)(methyl)selane (3c)
one (6a)
Yield: 90% (358 mg), yellow solid, mp 75e77 C. 1H NMR
ꢀ
Brown solid (87 mg, 61%) mp 282e284 C. H NMR (500 MHz,
ꢀ
1
3
3
3
3
(
1
2
300 MHz, CDCl
3
)
d
7.59 (d, JHH ¼ 8.8 Hz, 2H), 7.42 (d, JHH ¼ 7.5 Hz,
CDCl
3
):
d
7.96 (d,
J
HH ¼ 7.9 Hz, 1H), 7.34 (dt,
J
HH ¼ 7.02,
3
4
H), 7.35e7.28 (m, 2H), 7.20e7.11 (m, 1H), 6.91 (d, JHH ¼ 8.8 Hz,
J
HH ¼ 1.1 Hz, 1H), 7.26e7.22 (m, 4H), 7.22e7.19 (m, 3H), 7.17e7.13
1
3
3
4
H), 3.85 (s, 3H), 2.34 (s, 3H). C NMR (75 MHz, CDCl
3
)
d
158.80,
(m, 3H), 7.03 (dt, JHH ¼ 7.3, JHH ¼ 1.1 Hz, 1H), 6.92e6.89 (m, 5H),
3
13
139.21, 137.29, 133.37, 130.36, 127.78, 124.93, 124.36, 120.50, 116.81,
6.63 (d,
J
HH ¼ 8.2 Hz, 1H). C NMR (75 MHz, CDCl
3
): d 159.84,
19
113.58, 97.68, 84.70, 55.74, 7.46 ppm. F NMR (376 MHz, CDCl
3
):
.
144.04, 143.93, 143.17, 138.84, 138.64, 136.64, 134.10, 132.58, 131.30,
130.95, 129.22, 128.62, 128.31, 127.85, 127.49, 127.34, 127.21, 127.04,
126.36, 124.35, 119.37 ppm. IR (KBr): 1644, 1563, 1477, 1446 cm
ꢁ
1
d
ꢁ70.91 (s, 3F). IR (KBr): 2180, 1251, 1119, 1034, 834, 756, 517 cm
ꢁ
1
HRMS: Anal. Calcd. for 15ONF Se: 398.02655. Found:
C
18
H
3
.
3
98.02722.
HRMS: Anal. Calcd. for C29 20ONSe: 478.07046. Found: 478.06765.
H
4.3. Typical procedure for the synthesis of palladacycles
4.4.2. 2-(2-Methoxyphenyl)-3,4-diphenylbenzo[4,5]selenopheno
[
2,3-c]pyridin-1(2H)-one (6b)
ꢀ
1
To a solution of [PdCl
2
(PhCN)
C, alkyne 3 (0.25 mmol) was added. The mixture was stirred for
h at room temperature. The mixture was filtered through celite
2
] (0.25 mmol) in dry THF (4 mL) at
Brown solid (102 mg, 67%) mp 196e198 C. H NMR (500 MHz,
ꢀ
3
3
0
2
CDCl
3
):
d
7.95 (d, JHH ¼ 7.9 Hz, 1H), 7.32 (t, JHH ¼ 7.9 Hz, 1H), 7.25e
3 3
7.18 (m, 5H), 7.15 (t, JHH ¼ 7.8 Hz, 1H), 7.11 (d, JHH ¼ 7.5, 1H), 7.05e
3
bed and the filtrate was concentrated to 2 mL. Addition of n-hexane
10 mL) to the filtrate afforded orange precipitate. The orange solid
was filtered and washed with Et O to afford pure palladacycle.
6.98 (m, 2H), 6.94e6.86 (m, 4H), 6.82 (t, JHH ¼ 7.3 Hz, 1H), 6.74 (d,
3
3
13
(
J
HH ¼ 8.2 Hz, 1H), 6.64 (d, JHH ¼ 8.4 Hz, 1H), 3.75 (s, 3H). C NMR
2
(125 MHz, CDCl
3
): d 159.50, 154.44, 144.66, 143.87, 143.28, 138.76,
136.83, 134.09, 131.38, 131.34, 130.86, 130.32, 129.77, 129.52, 128.22,
4
.3.1. [(C
Yield: 70% (87 mg), orange solid. H NMR (300 MHz, DMSO-d
9.47e9.40 (m, 1H), 7.85e7.79 (m, 1H), 7.74 (s, 1H), 7.36e7.25 (m,
8
H
4
Se-3-)C(]NeC
6
H
5
)(CF
3
)Pd(
m
-Cl)]
2
(4a)
127.81, 127.47, 127.35, 127.05, 126.66, 126.30, 124.23, 120.29, 119.03,
111.37, 55.38 ppm. IR (KBr): 1645, 1500 cm . HRMS: Anal. Calcd. for
C H O NSe: 508.08103 and observed 508.07831.
30 22 2
1
ꢁ1
6
)
d
4
d
H), 7.11 (d, 3
122.70, 123.34, 124.72, 125.51, 127.07, 127.93, 128.12, 128.60,
29.36, 131.16, 132.09, 132.62, 144.10, 144.50, 145.70, 165.02 ppm.
J
HH ¼ 7.4 Hz, 2H). C NMR (75 MHz, DMSO-d
13
6
)
4.4.3. 2-(4-Methoxyphenyl)-3,4-diphenylbenzo[4,5]selenopheno
1
[2,3-c]pyridin-1(2H)-one (6c)
1
9
ꢀ
1
F NMR (376 MHz, DMSO-d
6
):
332, 1159, 755 cm . Elemental analysis: Anal. Calcd. for
Pd Se : C, 38.97; H, 1.84; N, 2.84. Found: C, 39.09; H,
d
ꢁ58.29 (s, 3F). IR (KBr): 1576,1445,
White solid (108 mg, 71%) mp 314e316 C. H NMR (500 MHz,
ꢁ1
3
3
1
C
CDCl
3
):
d
7.95 (d, JHH ¼ 7.9 Hz, 1H), 7.33 (t, JHH ¼ 7.5 Hz, 1H), 7.25e
H18Cl
32 2
F
6
N
2
2
2
7.22 (m, 3H), 7.21e7.16 (m, 2H), 7.07e6.99 (m, 3H), 6.97e6.85 (m,
6H), 6.73 (d, JHH ¼ 8.7 Hz, 2H), 6.61 (d, JHH ¼ 8.4 Hz, 1H), 3.71 (s,
3
3
1.77; N, 2.97.

20
S.S. Racharlawar et al. / Journal of Organometallic Chemistry 757 (2014) 14e20
3
1
1
H). 13C NMR (125 MHz, CDCl
26.37, 127.12, 127.21, 127.34, 127.47, 127.86, 128.30, 130.16, 130.94,
31.35, 131.58, 132.52, 134.26, 136.73, 138.66, 143.20, 144.01, 144.48,
3
):
d
55.34, 113.94, 119.43, 124.33,
References
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ꢁ1
158.68, 160.15 ppm. IR (KBr): 1645, 1508, 1249 cm . HRMS: Anal.
Calcd. for C30 NSe: 508.08103. Found: 508.08099.
H
22
O
2
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[
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4
.4.4. 2-(2-Methoxyphenyl)-3,4-diphenylbenzo[4,5]thieno[2,3-c]
pyridin-1(2H)-one (7a)
Brown solid (95 mg, 69%) mp 264e266 C. H NMR (500 MHz,
ꢀ
1
3
3
[
9] A.M. Lone, B.A. Bhat, G. Mehta, Tetrahedron Lett. 54 (2013) 5619e5623.
CDCl
3
):
d
7.93 (d, JHH ¼ 8.2 Hz, 1H), 7.41 (t, JHH ¼ 7.1 Hz, 1H), 7.27e
3 4
[10] B. Bogányi, J. Kámán, Tetrahedron 69 (2013) 9512e9519.
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7
.24 (m, 5H), 7.23e7.20 (m, 1H), 7.16 (dt, JHH ¼ 6.7, JHH ¼ 1.7 Hz,
[
H), 7.10 (dd, 3
J
HH ¼ 7.8,
4
J
HH ¼ 1.7 Hz, 1H), 7.06 (dt, 3JHH ¼ 6.1,
1
54 (2013) 3805e3809.
4
J
HH ¼ 1.1 Hz, 1H), 7.02e6.99 (m, 1H), 6.94e6.88 (m, 3H), 6.82 (dt,
[12] T. Mori, T. Nishimura, T. Yamamoto, I. Doi, E. Miyazaki, I. Osaka, K. Takimiya,
3JHH ¼ 7.6, JHH ¼ 1.1 Hz, 1H), 6.74 (dd, JHH ¼ 8.4, JHH ¼ 1.0 Hz, 1H),
4
3
4
J. Am. Chem. Soc. 135 (2013) 13900e13913.
[
13] K. Liu, F. Jia, H. Xi, Y. Li, X. Zheng, Q. Guo, B. Shen, Z. Li, Org. Lett. 15 (2013)
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J. Popelis, Eur. J. Med. Chem. 46 (2011) 3434e3443.
3
13
6
.65 (d, JHH ¼ 8.4 Hz, 1H), 3.74 (s, 3H). C NMR (75 MHz, CDCl
3
):
2
d
55.40, 111.43, 117.83, 120.33, 123.21, 124.08, 125.84, 126.71, 127.12,
27.41, 127.53, 127.86, 128.22, 129.67, 129.78, 130.46, 130.96, 131.27,
31.32, 134.04, 135.93, 136.68, 140.34, 142.96, 143.89, 154.58,
[
1
1
[
ꢁ1
158.51 ppm. IR (KBr): 1653, 1500 cm . HRMS: Anal. Calcd. for
30 22 2
C H O
NS: 460.13658. Found 460.13477.
[
[
[
4
.4.5. 2-(4-Methoxyphenyl)-3,4-diphenylbenzo[4,5]thieno[2,3-c]
pyridin-1(2H)-one (7b)
White solid (107 mg, 78%) mp 302e304 C. H NMR (300 MHz,
ꢀ
1
3
3
CDCl
3
):
d
7.93 (d, JHH ¼ 7.9 Hz, 1H), 7.41 (t, JHH ¼ 8.1 Hz, 1H), 7.29e
[
23] E. Alvaro, J.F. Hartwig, J. Am. Chem. Soc. 131 (2009) 7858e7868.
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7
.18 (m, 3H), 7.10e7.02 (m, 4H), 6.97e6.88 (m, 6H), 6.74 (d,
3
3
13
J
HH ¼ 8.9 Hz, 2H), 6.63 (d, JHH ¼ 8.3, 1H), 3.72 (s, 3H). C NMR (75
MHz, CDCl ): 55.29,113.89, 118.14, 123.23, 124.14, 125.82, 127.12,
27.23, 127.34, 127.48, 128.27, 129.96, 130.21, 130.97, 131.20, 131.49,
34.12, 135.75, 136.50, 140.15, 142.94, 143.62, 158.62, 159.12 ppm. IR
120 (1998) 9205e9219.
[
[
25] J. Louie, J.F. Hartwig, J. Am. Chem. Soc. 117 (1995) 11598e11599.
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York, 1984.
[27] A.T. Hutton, G. Wilkinson, R.D. Gillard, J.A. McCleverty (Eds.), Comprehensive
Coordination Chemistry, vol. 5, Pergamon, Oxford, 1984, p. 1131.
3
d
1
1
ꢁ1
(
22 2
KBr): 1653, 1506, 1248 cm . HRMS: Anal. Calcd. for C30H O NS:
[
[
28] I.P. Beletskaya, V.P. Ananikov, Eur. J. Org. Chem. 21 (2007) 3431e3444.
29] C.S. Bryan, J.A. Braunger, M. Lautens, Angew. Chem. Int. Ed. 48 (2009) 7064e
4
60.13658. Found: 460.13258.
7068.
[
[
[
[
[
30] B. Gabriele, R. Mancuso, E. Lupinacci, L. Veltri, G. Salerno, C. Carfagna, J. Org.
4
.4.6. 2,3-Bis(4-methoxyphenyl)-4-phenylbenzo[4,5]thieno[2,3-c]
Chem. 76 (2011) 8277e8286.
31] P.R. Likhar, S.M. Salian, S. Roy, M. Lakshmikantam, B. Sridhar, K.V. Mohan,
B. Jagadeesh, Organometallics 28 (2009) 3966e3969.
32] M.S. Subhas, S.S. Racharlawar, B. Sridhar, P.K. Kennady, P.R. Likhar,
M. Lakshmikantam, S.K. Bhargava, Org. Biomol. Chem. 8 (2010) 3001e3006.
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J. Organomet. Chem. 706e707 (2012) 128e134.
pyridin-1(2H)-one and 2,4-bis(4-methoxyphenyl)-3-phenylbenzo
[4,5]thieno[2,3-c]pyridin-1(2H)-one (7c þ 7d)
ꢀ
1
Brown solid (110 mg, 75%) mp 290e292 C. H NMR (300 MHz,
CDCl
3
): d 7.95e7.89 (m, 1H), 7.46e7.37 (m, 1H), 7.31e7.25 (m, 3H),
7.24e7.15 (m, 2H), 7.14e7.01 (m, 4H), 6.98e6.88 (m, 2H), 6.84e6.70
34] N. Beydoun, M. Pfeffer, Synthesis (1990) 729e731.
3
3
(
(
m, 5H), 6.60 (d, JHH ¼ 8.3 Hz, 1H), 6.46 (d, JHH ¼ 8.9 Hz, 1H), 3.80
[35] N. Beydoun, M. Pfeffer, A. DeClan, J. Fischer, Organometallics 10 (1991) 3693e
697.
13
3
s, 1H), 3.74 (s, 2H), 3.72 (s, 1H), 3.62 (s, 2H). C NMR (75 MHz,
): 158.23, 143.48, 136.76, 135.80, 134.37, 132.18, 132.13,
31.72, 131.17, 130.91, 130.41, 130.18, 130.12, 128.64, 128.32, 127.42,
27.27, 127.19, 126.54, 125.93, 125.85, 124.18, 124.13, 123.23, 118.43,
13.92, 113.86, 113.66, 112.55, 93.44, 55.27, 55.10, 54.87, ppm. IR
[36] J. Chengebroyen, M. Linke, M. Robitzer, C. Sirlin, M. Pfeffer, J. Organomet.
CDCl
1
1
1
3
d
Chem. 687 (2003) 313e321.
[37] G. Wu, A.L. Rheingold, S.J. Geib, R.F. Heck, Organometallics 6 (1987) 1941e
1946.
[
38] G. Wu, S.J. Geib, A.L. Reighngold, R.F. Heck, J. Org. Chem. 53 (1988) 3238e
241.
39] C.T. Bui, B.L. Flynn, J. Comb. Chem. 8 (2006) 163e167.
3
ꢁ
1
(
4
KBr): 1651, 1510, 1247 cm . HRMS: Anal. Calcd. for C31
90.14714. Found: 490.14442.
24 3
H O NS:
[
[40] L. Cuesta, D. Prat, T. Soler, R. Navarro, E.P. Urriolabeitia, Inorg. Chem. 50 (2011)
598e8607.
8
[
[
41] J. Dupont, C.S. Consorti, J. Spencer, Chem. Rev. 105 (2005) 2527e2571.
42] S. Nieto, P. Arnau, E. Serrano, R. Navarro, T. Soler, C. Cativiela, E.P. Urriolabeitia,
Inorg. Chem. 48 (2009) 11963e11975.
Acknowledgements
[
43] J. Vicente, I. Saura-Llamas, J. Turpin, D. Bautista, M.C. Ramirez de Arellano,
S. S. R thanks CSIR, India and D.S and M. V. K thank UGC for their
fellowships.
P.G. Jones, Organometallics 28 (2009) 4175e4195.