Synthesis of novel benzoxazocino quinoliniums and quinolones under PTC conditions and their application in Suzuki cross coupling reaction for the construction of polynuclear heteroaromatics

Article abstract of DOI:10.1016/j.tet.2009.06.061

A general and highly efficient synthetic protocol under phase transfer catalytic condition has been established for the synthesis of fused tetracyclic oxazocinoquinolone analogues which served as the precursors for novel biaryl quinolones using microwave

Full text of DOI:10.1016/j.tet.2009.06.061

Tetrahedron 65 (2009) 6941–6949
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Synthesis of novel benzoxazocino quinoliniums and quinolones under PTC
conditions and their application in Suzuki cross coupling reaction for the
construction of polynuclear heteroaromatics
Krishnendu B. Sahu a, Abhijit Hazra a, Priyankar Paira a, Pritam Saha a, Subhendu Naskar a,y
Manuela Weber b
,
b,
Rupankar Paira a, Sukdeb Banerjee a, Niranjan P. Sahu a, Nirup B. Mondal a , Peter Luger
,
*
a Indian Institute of Chemical Biology, Council of Scientific & Industrial Research, 4 Raja SC Mullick Road, Jadavpur, Kolkata 700 032, India
b Freie Universita¨t Berlin, Institut fu¨r Chemie und Biochemie/Kristallographie, Fabeckstr. 36a, D-14195, Berlin, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
A general and highly efficient synthetic protocol under phase transfer catalytic condition has been es-
tablished for the synthesis of fused tetracyclic oxazocinoquinolone analogues which served as the pre-
cursors for novel biaryl quinolones using microwave assisted Suzuki cross coupling reaction.
Ó 2009 Elsevier Ltd. All rights reserved.
Received 16 February 2009
Received in revised form 16 June 2009
Accepted 16 June 2009
Available online 21 June 2009
Keywords:
PTC
Benzoxazocinoquinolone
Biaryl quinolones
Suzuki coupling
1. Introduction
hydroxyquinolines leading to the formation of tetracyclic quinoli-
nium cations and the corresponding quinolones having an benzox-
Important pharmaceuticals oftenpossess heterocyclic moieties as
their building blocks.1 The extensive use of heterocyclic compounds
may be attributed to the wide range of reaction types available that
facilitate subtle structural modifications in the heterocyclic com-
pounds.2–4 Thus, investigations towards the understanding of re-
activity of heterocyclic compounds are gaining significance,
especially expedient syntheses leading to N-heteroaromatics which
are potent inhibitors of lymphocyte apoptosis5 and often form the
framework of DNA intercalating agents.6,7 Great efforts have, there-
fore, been made to discover and optimize new reactions/methodolo-
gies to facilitate the construction of heterocycles.8,9 In this aspect
phase transfer catalysis has long been recognized as a versatile
methodology for organic synthesis in industry, academia and in
process chemistry.10 As a part of our continuing investigation on
phase transfer catalysis for the construction of structurally unique N-
heteroaromatics,11,12 we report herein a one-pot reaction of 8-
azocino ring system like nefopam,13–17 a widely used nonopioid
analgesic. The synthesized molecules have further been utilized for
the construction of structurally unique class of polycyclic hetero-
aromatics via Suzuki cross coupling reaction,18,19 which has emerged
as one of the most important carbon–carbon bond forming methods
in the synthesis of pharmaceutical agents, organic materials, as well
as natural products.20–23
2. Result and discussion
Initially, the reaction of 8-hydroxyquinoline (1a) with
a, -
a0
dibromo-ortho xylene (2) was studied under phase transfer cat-
alytic condition and the progress of the reaction was monitored
by TLC. The reaction was observed to be completed within 10 h.
Usual workup followed by chromatographic separation afforded
two products, characterized as benzoxazocino quinolinium (3a)
and benzoxazocino quinolone (4a) from their MS, 1H and 13C NMR
spectral analysis. This method was extended to differently
substituted 8-hydroxyquinolines viz. 5-chloro (1b), 5,7-dibromo
(1c), 5-chloro-7-iodo (1d), and 2-methyl (1e) derivatives. In all
these cases quinolinium cations (3a–e) and their corresponding
quinolones (4a–d) were isolated in excellent yields (Table 1). The
* Corresponding author. Tel.: þ91 33 24733491; fax: þ91 33 2473 5197.
E-mail addresses: nirup@iicb.res.in (N.B. Mondal), luger@chemie.fu-berlin.de
(P. Luger).
y
Tel.: þ49 30 838 53411; fax: þ49 30 838 53464.
0040-4020/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2009.06.061

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K.B. Sahu et al. / Tetrahedron 65 (2009) 6941–6949
Table 1
Construction of tetracyclic quinoliniums and quinolones using 8-hydroxy quinolines (1a–e) and
a
,
a
0-dibromo-o-xylene (2)a
8 Hydroxy quinoline
Alkylating agents
Time (h)
Productb (%)c
Quinolinium
Quinolone
N
O
N
O
Br
O
Br
Br
N
OH
1a
8
2
3a (30)
4a (60)
Cl
Cl
Cl
N
O
N
O
Br
Br
Br
O
10
N
OH
1b
2
3b (35)
4b (45)
Br
Br
Br
Br
N
Br
N
O
Br
Br
Br
O
O
9
Br
N
2
OH
1c
3c (25)
4c (65)
Cl
Cl
Cl
I
N
I
N
O
Br
Br
Br
O
O
9
I
N
2
OH
1d
3d (35)
4d (40)
Br
Br
N
CH3
Br
N
O
N
CH3
6
O
O
OH
2
1e
3e (40)
4a (35)
a
All the reactions were conducted with 8-hydroxy quinoline and dibromo-o-xylene under PTC condition.
All the products are characterized by mass, 1H, 13C NMR.
Isolated yield.
b
c
pathway for the formation of quinoliniums (3a–e) from 8-
observed in the 1H NMR spectra of all the quinolinium cations
hydroxyquinolines (1a–e) might have occurred through initial
ether formation followed by intramolecular cyclization. We be-
lieve that the conversion of these quinoliniums (3a–e) to quino-
lones (4a–d) has occurred via oxidative pathway (Schemes 1 and
2) as described for tricyclic quinolones.12 However, for further
confirmation of the reaction mechanism, we performed sodium
borohydride reduction reaction on a model substrate 3c and were
able to isolate the key intermediate [III] and characterised by
spectral analysis (1H, 13C NMR). The gradual transformion of in-
termediate III to quinolone (4c) as depicted in Scheme 3 strongly
supports the porposed mechanism of quinolone formation from
quinolinium via the proposed oxidative pathway. The spectral
data (1H, 13C NMR and MS) of all the quinolones (4a–d) agreed
well with the proposed structures but some ambiguity was
(3a–e). The protons of N–CH2 group gave rise to two doublets
with one of the two protons resonating in aromatic region (d 7.6–
7.8). In the cases of quinolinium or isoquinolinium N-benzyl
bromides the protons of the N–CH2 group usually generate a sin-
glet at
d
6.05–6.70.24 The important correlations as revealed by 2D
NMR analysis of quinolinium 3c are shown in Figure 1. NOE re-
sults indicate that the more deshielded proton is not coplanar
with the aromatic ring. The major contribution to its downfield
shift is likely to be due to the near parallel orientation of the C–H
bond with the p-orbitals of the aromatic ring(s), allowing greater
overlap. For unambiguous determination of the structures, single
crystal X-ray analysis of quinolinium 3c and quinolone 4a was
carried out. Two molecules of 3c formed the asymmetric unit, the
unit cell consisting of two [C17H12NOBr2]þ cations, two Brꢀ anions

K.B. Sahu et al. / Tetrahedron 65 (2009) 6941–6949
6943
R1
R1
R1
Br
Br
(i)
(ii)
+
R2
N
3(a-d)
R2
R2
N
R2
N
Br
Br
O
OH
1(a-d)
O
N
2
R1
R1
R1
H
OH
R2
N
N
OH
R2
Br
OH
H
3(a-d)
O
O
O
R1
II
R2
N
I
O
R1
III
(i) CH2Cl2, 10% NaOH; (ii) Bu4N Br , rt, 8-10 hr
O2
R2
N
O
O
a. R1= R2 =R3= H; b. R1 = Cl, R2 = H;
c. R1 = R2 = Br; d. R1 = Cl, R2 = I
4(a-d)
Scheme 1. Plausible reaction pathway leading to fused quinolone analogues (4a–d).
Br
Br
(i)
(ii)
+
Me
Me
Br
N
N
Me
Br
N
OH
1e
O
O
2
3e
e
O
H
O2
O2
N
O
OH
N
N
CH2
N
CH2
Br
I
O
O
O
O
I
II
III
O
H
O
O
OH
H2O
N
O
II
N
N
O
OH
O
O
O
V
4a
IV
(i) CH2Cl2, 10% NaOH; (ii) Bu4NBr, rt, 8-10hr
Scheme 2. Plausible reaction pathway leading to fused quinolone 4a from 1e.
and two water molecules. The ORTEP representations of the
molecular structures of 3c and 4a, showing also the atomic
numbering, is depicted in Figure 2. The molecular structures of 3c
and 4a consist of a tetracyclic system of three planar six mem-
bered rings and one non-planar eight-membered ring. There are
a number of short contacts between molecule 1 of 3c, the counter
ions and the water molecules as illustrated in Figure 3, while
there are no intermolecular interactions of relevance seen in the
crystal lattice of 4a.
Br
Br
Br
NaBH4,H2O
rt, 5 min
O2
Br
N
Br
N
Br
N
O
O
O
O
3c
III
4c
Afterwards, we attempted to arylate the dihalo-substituted
quinolones (4c/4d) with differently substituted aryl boronic acids
following the Suzuki coupling reaction under both traditional
Scheme 3. Sodium borohydride reduction of quinolinium 3c for the isolation of in-
termedeate III.

6944
K.B. Sahu et al. / Tetrahedron 65 (2009) 6941–6949
Br
H
N
8.79
H
H
10.08
H
Br
6.05
H
H
63.6
O
7.28
75.8
6.05
H
7.76
H
5.59
H
H
7.31
H
H
Figure 3. Short contacts in the crystal lattice of 3c with contributions of molecule 1 of
3c, the counter ions and the water molecules as illustrated here.
Figure 1. Important correlations COSY (d), HMBC (/), NOESY (
).
heating and microwave conditions25 for the generation of poly-
cyclic heteroaromatics (Scheme 4). Screening was done with
various catalysts, bases, solvents and reaction conditions (mi-
crowave and heating) to optimize the reaction of dibromo-
substituted quinolone (4c) with benzene boronic acid (Table 2).
The microwave condition was found to be more effective than the
traditional heating condition with respect to the yield of the
products and the reaction time. Pd(PPh3)4 (3 mol %) proved to be
the most effective catalyst when the reaction being carried out in
DMF/H2O (10:1) using Na2CO3 as a base (Table 2, entry 13). The
reaction was also performed under aerobic conditions using
Pd(Cl)2 as catalyst without the presence of any ligand. The re-
action proceeded smoothly but the yield of the biaryl products
was slightly lower than with Pd(PPh3)4. It might have happened
that under the reaction condition Pd nanoparticles are formed.
Br
Ar
Br
(i)
(i)
Br
N
O
Ar
N
O
Br
Br
N
O
O
O
4c
5a-e
3c
Cl
Cl
Cl
(i)
(i)
Ar
N
O
I
N
O
I
N
Br
O
O
O
This coupling reaction was applied on
a
chloro-iodo
4d
(i) ArB(OH)2, 3mol% Pd(PPH3)4 , Na2CO3, MW.
6a-e
substituted quinolone (4d). Under the reaction conditions 4c
yielded a diarylated quinolone (5a), 4d yielded only a mono
arylated one (6a). Similar diarylated and monoarylated quinolones
(5a and 6a) were also obtained from the dihalo substituted qui-
noliniums 3c and 3d (Scheme 4). By following TLC at short in-
terval, it was observed that these quinoliniums (3c, 3d) were first
transformed to quinolones (4c, 4d) in aerobic condition within
5 min and finally yielded the common Suzuki products (5a and
6a). However, in inert atmosphere neither the quinolones nor the
3d
Scheme 4. Suzuki reaction of quinoliniums (3c/3d) and quinolones (4c/4d) with aryl
boronic acid.
coupling products could be isolated. For the rationalization of this
coupling reaction different boronic acids were used to synthesize
both the mono and diarylated quinolones from 3c, 4c and 3d, 4d
(Table 3).
Figure 2. ORTEP representations29,30of the title compounds 3c (cationic part, top) and 4a (bottom), the displacement ellipsoids are drawn at a probability of 50%.

K.B. Sahu et al. / Tetrahedron 65 (2009) 6941–6949
6945
Table 2
these molecules for the construction of novel polynuclear hetero-
aromatics utilizing the Suzuki reaction. The novelty of this versatile
methodology lies in the operational simplicity, environment
friendly mild reaction condition, and use of readily available starting
materials. We presume that the structural similarities of these
molecules with nefopam may show similar biological activities.
Optimization of Suzuki coupling reaction conditionsa
Entry Catalyst
Conditions Base
Solvent
Temp Time
(ꢁC)
Yield
(%)
1
2
3
PdCl2(PPh3)2 Heat
K2CO3
K2CO3
Na2CO3 Toluene
Toluene
Toluene
100
120
145
24 h
16 h
18 h
10
25
20
Pd(PPh3)4
Pd(OAc)2/
PPh3
4. Experimental section
4.1. General experimental
4
5
6
7
8
9
10
Pd(PPh3)4
Pd(PPh3)4
Pd(PPh3)4
Pd(PPh3)4
PdCl2
Cs2CO3 DMF
145
18 h
16 h
24 h
24 h
16 h
25
60
20
10
55
Na2CO3 DMF/water 145
K3PO4 DMF/water 140
Na2CO3 THF/water 145
Na2CO3 DMF/water 145
Melting points were determined with capillary melting point
apparatus and are uncorrected. IR spectra were recorded on
a JASCO 410 FTIR spectrometer in KBr pellets. The NMR spectra
were taken on a BRUKER 300/600 DPX spectrometer operating at
300/600 MHz for 1H and 75/150 MHz for 13C respectively, with
tetramethylsilane (TMS) as an internal standard and the chemical
PdCl2(PPh3)2 MWb
Pd(OAc)2/
PPh3
K2CO3
Toluene
120
120
10 min 20
15 min 30
Na2CO3 Toluene
11
12
13
14
Pd(PPh3)4
Pd(PPh3)4
Pd(PPh3)4
Pd(Cl)2
Cs2CO3 DMF
120
10 min 52
10 min 30
10 min 72
10 min 65
K3PO4
DMF/water 120
Na2CO3 DMF/water 120
Na2CO3 DMF/water 120
shifts are reported in
d units. Mass spectra and HRMS (positive
a
Suzuki coupling reaction was optimised by choosing quinolone (4c) and benzene
mode) were obtained using LC-ESI-Q-TOF micro mass spectrom-
eter. All chromatographic purification was performed on silica gel
(100–200 mesh) and was obtained from E. Merck India Ltd.,
Mumbai. Thin layer chromatography (TLC) was performed on pre-
coated silica gel 60 F254 aluminium sheets (E. Merck, Germany)
using the different solvent system and spots were visualized
either under UV torch or on heating after spraying Liebermann–
Burchard solution. A mono-mode microwave reactor, manufac-
tured by CEM Corporation, USA was used for Suzuki reaction in
open mode. Organic solvents used for the chemical synthesis and
for chromatography acquired from E. Merck (India) were of
boronic acid as two model substrates.
All the MW experiments were performed at 150 W maximum power in open
vessel mode.
b
Table 3
Suzuki reaction of quinolinium/quinolone substrates with different aryl boronic
acids
Quinolinium/
quinolone
Boronic acid
Time (min) Product Isolated yield (%)
Heatinga
MWb
3c/4c
15
5a
65
75
B(OH)2
analytical grade. 8-Hydroxyquinoline derivatives (1a–e),
a, -
a0
dibromo-o-xylene (2), phase transfer catalyst (tetra butyl ammo-
nium bromide) and boronic acids were purchased from Aldrich
Chemical Ltd (USA).
3c/4c
3c/4c
12
13
5b
5c
70
64
82
76
MeO
Me
B(OH)2
B(OH)2
4.2. General reaction procedure for the synthesis of fused
tetra cyclic quinolinium (3a–e) and quinolones (4a–d)
3c/4c
3c/4c
17
17
5d
5e
55
58
65
68
B(OH)2
B(OH)2
O
Appropriate amount of 8-hydroxyquinoline analogue (1a–e)
(3.3 mmol) was dissolved in 50 mL of dichloromethane in a 250 mL
RB flask followed by the addition of 50 mL of 10% aqueous NaOH
solution, and was stirred at room temperature for about 30 min.
a,a
0-Dibromo-o-xylene (2) (10 mmol, 1:3 ratio with respect to the
S
substrate) was added successively to the stirred solution and stir-
ring continued for 10 min. Finally, a catalytic amount of tetrabu-
tylammonium bromide (Phase Transfer Catalyst) (0.3224 g,
1 mmol) was added to the solution and the reaction mixture was
stirred at ambient temperature for 10 h. During the course of re-
action, TLC was performed after every 2 h to monitor the progress
of the reaction. After completion of the reaction, the contents of the
reaction mixture were poured to a separating funnel; the organic
layer was separated followed by extraction of the aqueous layer
thrice with 25 mL of dichloromethane. The entire aqueous layer
was further extracted with n-butanol for collecting the rest of the
compounds. All the organic layers were mixed together, washed
thoroughly with water until free from alkali, dried over sodium
sulfate and evaporated to dryness in a rotary evaporator under
reduced pressure. The residue was chromatographed over silica gel
(60–120 mesh), eluting with a mixture of hexane–ethyl acetate and
ethyl acetate–methanol in different ratios yielded the respective
fused quinolinium cation (3a–e) and its quinolone (4a–d).
3d/4d
3d/4d
3d/4d
3d/4d
15
16
17
20
6a
6b
6c
6d
50
55
63
58
62
63
74
72
B(OH)2
MeO
Me
B(OH)2
B(OH)2
B(OH)2
B(OH)2
O
3d/4d
19
6e
60
75
S
a
Suzuki coupling reaction under heating condition was carried out in DMF/H2O
using Pd(PPh3)4 catalyst and Na2CO3 at 140 ꢁC.
b
Suzuki coupling reaction under MW condition was carried out at 150 W, 120 ꢁ
in open vessal mode, other conditions were same as in heating mode.
C
3. Conclusion
4.2.1. Compound 3a
Brown solid, 30% yield. Mp 236–238 ꢁC; Rf (1% MeOH–CHCl3)
In summary, we have demonstrated a facile one-pot synthesis of
a novel class of fused tetracyclic heteroaromatics having a benzox-
azocino ring system. We have also demonstrated the application of
0.25; IR (KBr, cmꢀ1 3417, 3055, 2061, 1593, 1527, 1451; 1H NMR
) n
(300 MHz, DMSO-d6)
7.21–7.34 (4H, m), 7.74 (1H, d, J¼7.5 Hz), 8.01 (1H, t, J¼7.8 Hz), 8.18–
d
5.46 (1H, d, J¼15.3 Hz), 6.01–6.09 (2H, m),

6946
K.B. Sahu et al. / Tetrahedron 65 (2009) 6941–6949
8.25 (3H, m), 9.25 (1H, d, J¼8.4 Hz), 10.05 (1H, d, J¼5.7 Hz); 13C
m/z calcd for
441.9088.
C
17H11Br2NO2Na: [MþNa]þ 441.9054; found:
NMR (75 MHz, DMSO-d6)
d
63.9 (CH2), 79.2 (CH2), 123.7 (CH), 128.0
(CH), 128.5 (CH), 129.4 (CH), 130.9 (CH), 131.0 (CH), 131.8 (CH), 132.1
(C), 132.8 (CH), 133.1 (C), 137.0 (2ꢂC), 148.7 (CH), 149.9 (C), 151.6
(CH). HRMS [ESI] m/z calcd for C17H14NO: [MꢀBr]þ 248.1075;
found: 248.1055.
4.2.7. Compound 3d
White solid, 35% yield. Mp 77–79 ꢁC; Rf (1% MeOH–CHCl3) 0.30;
IR (KBr, cmꢀ1 3428, 3056, 1584, 1503, 1385, 1363, 750; 1H NMR
) n
(300 MHz, DMSO-d6)
d
5.58 (1H, d, J¼15.3 Hz), 6.00 (2H, m), 7.33
4.2.2. Compound 4a
(4H, m), 7.77 (1H, d, J¼7.2 Hz), 8.32 (1H, dd, J¼6.0, 8.4 Hz), 8.71 (1H,
White solid, 60% yield. Mp 186–188 ꢁC; Rf (60% pet. ether–
s), 9.31 (1H, d, J¼8.4 Hz), 10.04 (1H, d, J¼5.7 Hz); 13C NMR (75 MHz,
chloroform) 0.50; IR (KBr, cmꢀ1
)
n
3446, 3011, 2908, 1647, 1580,
DMSO-d6) d 63.5 (CH2), 76.2 (CH2), 104.7 (C), 124.1 (CH), 127.0 (CH),
1454, 1244; 1H NMR (300 MHz, CDCl3)
d
5.11 (1H, d, J¼15.0 Hz),
128.5 (CH), 128.9 (C), 129.1 (C), 130.1 (CH), 131.7 (CH), 133.3 (C),
135.3 (2ꢂC),139.5 (CH),144.3 (CH),148.3 (C),151.8 (CH). HRMS [ESI]
m/z calcd for C17H12ClINO: [MꢀBr]þ 407.9652; found: 407.9662.
5.76–5.90 (2H, m), 6.31 (1H, d, J¼13.5 Hz), 6.64 (1H, d, J¼9.6 Hz),
6.97–6.99 (1H, m), 7.06–7.25 (4H, m), 7.34 (1H, d, J¼7.5 Hz), 7.45
(1H, d, J¼9.6 Hz), 7.52–7.55 (1H, m); 13C NMR
d 44.7 (CH2), 78.6
(CH2), 121.7 (CH), 122.8 (CH), 122.9 (C), 125.3 (CH), 125.4 (CH), 125.6
(CH), 128.0 (2ꢂCH), 132.5 (CH), 133.2 (C), 134.6 (C), 136.0 (C), 138.6
(CH), 146.6 (C), 162.1 (C). HRMS [ESI] m/z calcd for C17H13NO2Na:
[MþNa]þ 286.0844; found: 286.0855.
4.2.8. Compound 4d
White solid, 65% yield, Mp 162–164 ꢁC; Rf (60% pet. ether–
chloroform) 0.50; IR (KBr, cmꢀ1
)
n
3446, 1660, 1558, 1443, 1418,
1233,1143, 743; 1H NMR (300 MHz, CDCl3)
d
5.29 (1H, d, J¼15.3 Hz),
5.72 (1H, d, J¼15.3 Hz), 5.87 (1H, d, J¼13.5 Hz), 6.15 (1H, d,
J¼13.8 Hz), 6.76 (1H, d, J¼9.6 Hz), 7.05 (1H, m), 7.24 (2H, m), 7.59
(1H, m), 7.68 (1H, s), 7.96 (1H, d, J¼9.9 Hz); 13C NMR (75 MHz,
4.2.3. Compound 3b
Brown solid, 35% yield. Mp 76–78 ꢁC; Rf (1%MeOH–CHCl3) 0.20;
IR (KBr, cmꢀ1
DMSO-d6)
)
n
3432, 3073, 1585, 1527, 1153; 1H NMR (300 MHz,
CDCl3) d 46.4 (CH2), 77.7 (CH2), 95.9 (C), 120.9 (C), 123.7 (CH), 126.1
d
5.49 (1H, d, J¼15.0 Hz), 6.05–6.10 (2H, m), 7.22–7.38
(CH), 128.80 (CH), 128.82 (CH), 129.7 (C), 132.9 (CH), 133.0 (CH),
134.8 (2ꢂC), 135.2 (CH), 135.6 (C), 145.7 (C), 162.2 (C). HRMS [ESI],
m/z calcd for C17H11ClINO2Na: [MþNa]þ 445.9421; found:
445.9438.
(4H, m), 7.73 (1H, d, J¼7.2 Hz), 8.23 (2H, dd, J¼15.0, 8.4 Hz), 8.33
(1H, dd, J¼8.7, 5.7 Hz), 9.32 (1H, d, J¼8.7 Hz),10.15 (1H, d, J¼5.7 Hz);
13C NMR (75 MHz, DMSO-d6)
d 64.3 (CH2), 79.2 (CH2), 125.0 (CH),
127.9 (CH), 129.4 (CH), 129.5 (C), 129.7 (C), 131.03 (CH), 131.08 (CH),
131.8 (C), 132.0 (CH), 133.0 (CH), 134.4 (C), 136.9 (C), 144.9 (CH),
149.4 (C), 152.6 (CH). HRMS [ESI] m/z calcd for C17H13ClNO:
[MꢀBr]þ 282.0686; found: 282.0687.
4.2.9. Compound 3e
Gray crystalline solid, 40% yield. Mp 210–212 ꢁC; Rf (1% MeOH–
CHCl3) 0.20; IR (KBr, cmꢀ1
NMR (300 MHz, DMSO-d6)
)
n
3424, 3038, 1601, 1516, 1437, 1122; 1H
d
5.42 (1H, d, J¼14.7 Hz), 5.97 (2H, m),
4.2.4. Compound 4b
6.92 (1H, d, J¼14.4 Hz), 7.32 (3H, m), 7.60 (1H, d, J¼7.2 Hz), 7.92 (1H,
White crystal, 60% yield. Mp 176–177 ꢁC; Rf (60% pet. ether–
t, J¼8.1 Hz), 8.14 (3H, m), 9.06 (1H, d, J¼8.4 Hz); 13C NMR (75 MHz,
chloroform) 0.45; IR (KBr, cmꢀ1
)
n
3430, 3087, 2906, 1658, 1574,
DMSO-d6) d 24.7 (CH3), 57.2 (CH2), 78.7 (CH2), 127.3 (CH), 128.0
1448, 1243; 1H NMR (300 MHz, CDCl3)
d
5.10 (1H, d, J¼15 Hz), 5.78–
(2ꢂCH), 129.4 (CH), 130.2 (CH), 130.8 (CH), 131.0 (CH), 131.0 (C),
131.9 (C), 133.4 (CH), 134.6 (C), 137.4 (C), 146.8 (CH), 150.1 (C), 163.2
(C). HRMS [ESI] m/z calcd for C18H16NO: [MꢀBr]þ 262.1232; found:
262.1185.
5.90 (2H, m), 6.32 (1H, d, J¼13.5 Hz), 6.75 (1H, d, J¼9.9 Hz), 6.99–
7.02 (1H, m), 7.16–7.29 (4H, m), 7.50–7.53 (1H, m), 7.99 (1H, d,
J¼9.9 Hz); 13C NMR (75 MHz, CDCl3)
d 45.5 (CH2), 79.1 (CH2), 120.8
(C), 123.3 (CH), 124.0 (CH), 124.6 (C), 125.9 (CH), 126.2 (CH), 128.77
(CH), 128.83 (CH), 129.3 (C), 133.0 (CH), 134.9 (C), 135.3 (CH), 136.2
(C), 146.0 (C), 162.3 (C). HRMS [ESI] m/z calcd for C17H12ClNO2Na:
[MþNa]þ 320.0454; found: 320.0459.
4.2.9.1. Isolation and characterization of intermediate III from
3c. Quinolinium bromide 3c (0.5 mmol) was dissolved in 50 mL of
water in a 100 mL RB flask under argon atmosphere with contin-
uous stirring. A small amount of sodium borohydride was added
and stirring continued for about 5 min. The product III was
obtained by simple filtration of the reaction mixture followed by
washing with distilled water cautiously avoiding aerial oxidation
and kept under vacuum.
4.2.5. Compound 3c
Brown crystalline solid, 25% yield. Mp 151–152 ꢁC; Rf (1%
MeOH–CHCl3) 0.30; IR (KBr, cmꢀ1
)
n
3417, 3056, 2021, 1584,
1384, 1082; 1H NMR (300 MHz, DMSO-d6)
d
5.60 (1H, d,
J¼15.3 Hz), 6.03–6.1 (2H, m), 7.27–7.41 (4H, m), 7.78 (1H, d,
J¼7.5 Hz), 8.33 (1H, dd, J¼6.0, 8.7 Hz), 8.78 (1H, s), 9.27 (1H, d,
J¼8.7 Hz), 10.12 (1H, d, J¼5.7 Hz); 13C NMR (75 MHz, DMSO-d6)
Intermediate III was obtained as white powdered solid in
40%yield. Mp 140–141 ꢁC; Rf (60% pet. ether–chloroform) 0.50; 1H
NMR (300 MHz, CDCl3)
d
3.91 (2H, s), 4.60 (2H, s), 5.24 (2H, s), 7.05
50.8 (CH2), 58.2 (CH2), 77.7
d
64.5 (CH2), 76.7 (CH2), 121.0 (C), 125.4 (CH), 126.8 (C), 127.9
(7H, m); 13C NMR (75 MHz, CDCl3)
d
(CH), 129.5 (CH), 130.5 (C), 131.1 (CH), 131.8 (C), 132.8 (CH), 135.4
(C), 136.3 (C), 138.5 (CH), 146.8 (C), 147.9 (CH), 153.2 (CH). HRMS
[ESI] m/z calcd for C17H12Br2NO: [MꢀBr]þ 403.9286; found:
403.9345.
(CH2), 116.6 (C), 116.9 (C), 123.7 (C), 124.4 (CH), 124.8 (CH), 126.4
(CH),127.6 (CH),127.7 (CH),130.1 (CH),135.3 (C),135.7 (C),140.0 (C),
144.5 (C). MS [ESI] m/z for C17H13Br2NONa: [MþNa]þ 430.09.
4.3. General reaction procedure for the synthesis of
diarylated (5a–e) and mono arylated (6a–e) quinolones
by Suzuki cross coupling reaction
4.2.6. Compound 4c
White crystal, 65% yield, Mp 190–191 ꢁC; Rf (60% pet. ether–
chloroform) 0.50; IR (KBr, cmꢀ1
)
n
3431, 3071, 2927, 1658, 1556,
1422; 1H NMR (300 MHz, CDCl3)
d
5.38 (1H, d, J¼15.3 Hz), 5.73 (1H,
The Suzuki coupling reaction of dibromo quinolone (4c) with
benzene boronic acid, representative of the general reaction pro-
tocol, was carried out both in traditional heating and microwave
irradiation condition, RB flask was used for the former and micro-
wave vessel was used for the latter one.
d, J¼14.7 Hz), 5.85 (1H, d, J¼13.5 Hz), 6.28 (1H, d, J¼13.5 Hz), 6.75
(1H, d, J¼9.9 Hz), 7.04–7.07 (1H, m), 7.20–7.26 (2H, m), 7.53–7.56
(1H, m), 7.63 (1H, s), 7.91 (1H, d, J¼9.9 Hz); 13C NMR (75 MHz,
CDCl3)
d 46.0 (CH2), 76.9 (CH2), 119.4 (C), 121.4 (C), 121.6 (C), 123.6
(CH),126.3 (CH),128.9 (CH),129.0 (CH),130.6 (CH),132.8 (CH),134.8
(C), 135.8 (C), 136.4 (C), 137.8 (CH), 143.4 (C), 162.3 (C). HRMS [ESI],
Thus, for the standardization of the reaction in MW 0.1 g of (4c)
(0.23 mmol) was taken in a mortar followed by addition of benzene

K.B. Sahu et al. / Tetrahedron 65 (2009) 6941–6949
6947
boronic acid 0.0765 mg, (0.59 mmol), catalyst [Pd(PPh3)4]
(0.007 mmol), and base (Na2CO3) (1.8 mmol) and mixed well using
a pestle. The mixture was placed in microwave vessel with the
solvent DMF/H2O (10:1) and irradiated (150 W) for 10 min. The
reaction mixture transformed to brown-black and the bulk tem-
perature was found to be 120 ꢁC. After completion of the reaction,
the contents were cooled to room temperature. Water was added to
the mixture, the content was transferred to a separating funnel and
extracted with ethyl acetate. The organic layer was washed thor-
oughly with water until free from alkali, dried over anhydrous so-
dium sulfate, and evaporated to dryness in a rotary evaporator
under reduced pressure. The residue was chromatographed over
silica gel (60–120, mesh), eluting with a mixture of hexane–ethyl
acetate in different ratios.
The reaction that carried out under traditional heating condition
was performed in a 100 mL two-necked RB flask fitted with a guard
tube. The well-mixed mixture of the substrate, catalyst, reagent and
base was taken in the reaction flask followed by addition of the
solvent. The flask was placed on an oil bath with constant stirring
for 12 h at 140–145 ꢁC. After completion of the reaction, usual
workup followed by chromatographic separation yielded the
product. It was observed that the MW condition yielded higher
(76%, within 10 min) compared to the heating condition (55%, 12 h
with constant stirring) (Table 2).
138.0 (C), 143.0 (C), 162.9 (C). HRMS [ESI] m/z calcd for
C31H25NO2Na: [MþNa]þ 466.1783; found: 466.1767.
4.3.4. Compound 5d
White solid, Mp 195–196 ꢁC; Rf (60% pet. ether–chloroform)
0.45; IR (KBr, cmꢀ1 3442, 1657, 1589, 1455, 1425, 743; 1H NMR
) n
(300 MHz, CDCl3)
d
4.96 (1H, d, J¼15 Hz), 5.68 (1H, d, J¼15.3 Hz),
5.98 (2H, m), 6.61 (4H, m), 6.97 (1H, d, J¼6.9 Hz), 7.25 (3H, m), 7.57
(2H, s), 7.66 (1H, d, J¼6.9 Hz), 7.87 (1H, s), 8.07 (1H, d, J¼9.9 Hz); 13C
NMR (75 MHz, CDCl3)
d 47.2 (CH2), 76.8 (CH2), 109.8 (CH), 111.2
(CH), 111.5 (CH), 112.1 (CH), 118.9 (C), 120.5 (CH), 121.4 (CH), 125.2
(CH), 125.8 (C), 126.0 (C), 127.8 (2ꢂCH), 132.2 (CH), 134.5 (C), 135.1
(C), 135.2 (C), 136.1 (CH), 142.4 (CH), 142.7 (CH), 143.0 (C), 148.8 (C),
151.5 (C), 162.5 (C). HRMS [ESI], m/z calcd for C25H17NO4Na:
[MþNa]þ 418.1055; found: 418.1010.
4.3.5. Compound 5e
White solid. Mp 225–226 ꢁC; Rf (60% pet. ether–chloroform)
0.50; IR (KBr, cmꢀ1 3452, 1651, 1589, 1470, 1427, 790; 1H NMR
) n
(600 MHz, CDCl3)
d
4.70 (1H, d, J¼15.0 Hz), 5.46 (1H, d, J¼15.0 Hz),
5.99 (1H, d, J¼13.2 Hz), 6.30 (1H, d, J¼13.8 Hz), 6.62 (1H, d,
J¼10.2 Hz), 6.89 (1H, d, J¼7.2 Hz), 7.12 (1H, dd, J¼1.2, 5.4 Hz), 7.19
(1H, dt, J¼1.2, 7.8 Hz), 7.23 (1H, m), 7.28 (1H, s), 7.42 (1H, dd, J¼3.0,
5.4 Hz), 7.47 (1H, dd, J¼3.0, 4.8 Hz), 7.55 (1H, dd, J¼1.2, 4.8 Hz), 7.59
(1H, d, J¼7.2 Hz), 7.69 (1H, s), 7.70 (1H, s), 7.72 (1H, dd, J¼1.2,
4.3.1. Compound 5a
3.0 Hz); 13C NMR (150 MHz, CDCl3)
d 46.2 (CH2), 76.2 (CH2), 120.4
White solid, Mp 194–195 ꢁC; Rf (60% pet. ether–CHCl3) 0.60; IR
(C), 121.4 (CH), 124.1 (CH), 124.3 (CH), 125.61 (CH), 125.68 (CH),
125.72 (CH), 125.97 (CH), 128.1 (CH), 128.15 (CH), 128.4 (CH), 129.2
(CH), 132.0 (C), 132.5 (CH), 132.6 (C), 134.9 (C), 135.0 (C), 136.2 (C),
136.6 (CH), 137.5 (C), 139.3 (C), 143.2 (C), 162.8 (C). HRMS [ESI] m/z
calcd for C25H17NO2S2Na: [MþNa]þ 450.0598; found: 450.0594.
(KBr, cmꢀ1
CDCl3)
) n
3434, 1656, 1586, 1446, 1421, 701; 1H NMR (600 MHz,
4.58 (1H, d, J¼15.0 Hz), 5.33 (1H, d, J¼15.0 Hz), 5.98 (1H, d,
d
J¼13.8 Hz), 6.34 (1H, d, J¼13.8 Hz), 6.61 (1H, d, J¼10.2 Hz), 6.85 (1H,
d, J¼7.8 Hz), 7.13 (1H, s), 7.18 (1H, dt, J¼1.2, 7.8 Hz), 7.23 (1H, t,
J¼7.2 Hz), 7.32 (2H, m), 7.39 (1H, m), 7.43 (3H, m), 7.49 (2H, m), 7.57
(1H, d, J¼7.2 Hz), 7.61 (1H, d, J¼9.6 Hz), 7.66 (2H, m); 13C NMR
4.3.6. Compound 6a
(150 MHz, CDCl3)
d
46.1 (CH2), 76.2 (CH2), 120.2 (C), 121.4 (CH),
White solid. Mp 85–86 ꢁC; Rf (60% pet. ether–chloroform) 0.75;
125.7 (CH), 126.6 (CH), 127.7 (CH), 127.8 (CH), 128.09 (CH), 128.14
(CH), 128.4 (CH), 128.45 (CH), 129.3 (2ꢂCH), 129.86 (2ꢂCH), 129.90
(2ꢂCH), 132.5 (CH), 134.5 (C), 135.0 (C), 136.3 (C), 136.8 (CH), 137.4
(C), 137.7 (C), 137.9 (C), 139.0 (C), 143.0 (C), 162.8 (C). HRMS [ESI] m/z
calcd for C29H21NO2Na: [MþNa]þ 438.1470; found: 438.1484.
IR (KBr, cmꢀ1 3434, 1660, 1584, 1419; 1H NMR (300 MHz, CDCl3)
) n
d
4.47 (1H, d, J¼15 Hz), 5.27 (1H, d, J¼14.7 Hz), 5.91 (1H, d,
J¼13.5 Hz), 6.29 (1H, d, J¼13.5 Hz), 6.77 (2H, m), 7.18 (3H, m), 7.48
(4H, m), 7.60 (2H, m), 8.01 (1H, d, J¼9.6 Hz); 13C NMR (75 MHz,
CDCl3)
d 46.0 (CH2), 76.0 (CH2), 119.5 (C), 122.6 (CH), 125.4 (CH),
125.7 (CH), 128.19 (CH), 128.21 (CH), 128.27 (CH), 128.4 (C), 128.55
(2ꢂCH), 129.1 (2ꢂCH), 132.3 (CH), 134.5 (C), 134.8 (CH), 135.4 (C),
135.9 (C), 136.6 (C), 138.4 (C), 142.4 (C), 162.5 (C). HRMS [ESI], m/z
calcd for C23H16ClNO2Na: [MþNa]þ 396.0767; found: 396.0777.
4.3.2. Compound 5b
White solid, Mp 194–195 ꢁC; Rf (60% pet. ether–chloroform)
0.45; IR (KBr, cmꢀ1 3453, 1660, 1607, 1585, 1512, 1246, 836; 1H
) n
NMR (300 MHz, CDCl3)
d 3.84 (3H, s), 3.89 (3H, s), 4.59 (1H, d,
J¼15.0 Hz), 5.33 (1H, d, J¼15.0 Hz), 5.99 (1H, d, J¼13.5 Hz), 6.33 (1H,
d, J¼13.5 Hz), 6.62 (1H, d, J¼9.9 Hz), 6.84 (1H, d, J¼7.2 Hz), 6.96 (2H,
m), 7.02 (2H, m), 7.10 (1H, s), 7.20 (4H, m), 7.60 (4H, m); 13C NMR
4.3.7. Compound 6b
White solid. Mp 84–85 ꢁC; Rf (60% pet. ether–chloroform) 0.45;
IR (KBr, cmꢀ1
) n
3428, 1658, 1583, 1514, 1452, 1426, 1249; 1H NMR
(75 MHz, CDCl3)
d
46.1 (CH2), 55.3 (CH3), 55.3 (CH3), 76.0 (CH2),
(300 MHz, CDCl3)
d
3.90 (3H, s), 4.51 (1H, d, J¼15.0 Hz), 5.29 (1H, d,
113.8 (2ꢂCH),113.9 (2ꢂCH),120.07 (C), 120.9 (CH),125.7 (CH),126.5
(CH), 128.05 (CH), 128.07 (CH), 129.9 (C), 130.5 (2ꢂCH), 131.0
(2ꢂCH),131.3 (C),132.5 (CH),134.6 (C),135.0 (C),136.4 (C),136.9 (C),
137.0 (CH), 137.5 (C), 142.7 (C), 159.2 (C), 159.3 (C), 162.8 (C). HRMS
[ESI], m/z calcd for C31H25NO4Na: [MþNa]þ 498.1681; found:
498.1682.
J¼14.7 Hz), 5.92 (1H, d, J¼13.5 Hz), 6.29 (1H, d, J¼13.2 Hz), 6.78 (2H,
m), 7.04 (2H, m), 7.19 (3H, m), 7.54 (3H, m), 8.0 (1H, d, J¼9.9 Hz); 13C
NMR (75 MHz, CDCl3)
d 46.0 (CH2), 55.3 (CH3), 75.9 (CH2), 114.1
(2ꢂCH), 119.2 (C), 122.4 (CH), 125.4 (CH), 125.7 (CH), 128.2 (CH),
128.3 (CH), 128.4 (C), 128.8 (C), 130.4 (2ꢂCH), 132.4 (CH), 134.7 (C),
134.8 (CH), 135.5 (C), 136.0 (C), 138.1 (C), 142.4 (C), 159.6 (C), 162.6
(C). HRMS [ESI], m/z calcd for C24H18ClNO3Na: [MþNa]þ 426.0873;
found: 426.0910.
4.3.3. Compound 5c
White solid. Mp 104–105ꢁC; Rf (60% pet. ether–CHCl3) 0.75; IR
(KBr, cmꢀ1
CDCl3)
)
n
3445, 1659, 1586, 1426, 825; 1H NMR (300 MHz,
4.3.8. Compound 6c
d
2.40 (3H, s), 2.45 (3H, s), 4.60 (1H, d, J¼15 Hz), 5.32 (1H, d,
White solid. Mp 64–65 ꢁC; Rf (60% pet. ether–chloroform) 0.65;
J¼14.7 Hz), 6.0 (1H, d, J¼13.8 Hz), 6.33 (1H, d, J¼13.5 Hz), 6.60 (1H,
IR (KBr, cmꢀ1
) n
3434, 2922, 1660, 1583, 1450, 1421; 1H NMR
d, J¼9.9 Hz), 6.84 (1H, d, J¼7.2 Hz), 7.11 (1H, s), 7.27 (9H, m), 7.52
(300 MHz, CDCl3)
d
2.46 (3H, s), 4.50 (1H, d, J¼15.0 Hz), 5.29 (1H, d,
(3H, m); 13C NMR (75 MHz, CDCl3)
d
21.2 (CH3), 21.4 (CH3), 46.2
J¼15.0 Hz), 5.92 (1H, m), 6.29 (1H, d, J¼13.2 Hz), 6.78 (2H, m), 7.23
(CH2), 76.2 (CH2), 120.2 (C), 121.2 (CH), 125.8 (CH), 125.9 (C), 126.7
(CH), 126.9 (CH), 128.1 (CH), 128.2 (CH), 129.2 (CH), 129.3 (2ꢂCH),
129.5 (2ꢂCH), 129.7 (CH), 129.9 (CH), 132.6 (CH), 134.62 (C), 134.85
(C), 135.1 (C), 136.2 (C), 136.5 (C), 137.0 (CH), 137.5 (C), 137.6 (C),
(5H, m), 7.51 (3H, m), 8.01 (1H, d, J¼9.6 Hz); 13C NMR (75 MHz,
CDCl3)
d 21.3 (CH3), 46.0 (CH2), 75.9 (CH2), 119.3 (C), 122.4 (CH),
122.8 (C), 125.4 (CH), 125.7 (CH), 128.18 (CH), 128.21 (CH), 128.95
(2ꢂCH), 129.3 (2ꢂCH), 132.3 (CH), 132.6 (C), 133.6 (C), 134.6 (C),

6948
K.B. Sahu et al. / Tetrahedron 65 (2009) 6941–6949
134.8 (CH), 136.0 (C), 138.1 (C), 138.4 (C), 142.4 (C), 162.5 (C). HRMS
[ESI], m/z calcd for C24H18 ClNO2Na: [MþNa]þ 410.0924; found:
410.0929.
independent reflections 9386, unobserved (Fo<4s (Fo)) 4300, linear
absorption coeff.
m
¼71.9 cmꢀ1, Rint¼0.081, Rs¼0.083. After conver-
gence of refinements R1¼0.068, Rw¼0.164, GoF¼1.03.
4.3.9. Compound 6d
4.4.2. Crystal data for 4a
White solid. Mp 165–166 ꢁC; Rf (60% pet. ether–chloroform)
C17H13NO2, Mr¼263.28, light yellow block shaped crystals were
grown from CHCl3/Hexane. Dimensions of the specimen used for
X-ray experiments 0.62ꢂ0.60ꢂ0.20 mm. Space group triclinic
P1bar. Lattice constants (Å) a¼7.140(1), b¼8.596(1), c¼10.976(1),
0.55; IR (KBr, cmꢀ1 3428, 1660, 1586, 1443, 741; 1H NMR
) n
(300 MHz, CDCl3)
d
4.96 (1H, d, J¼15 Hz), 5.70 (1H, d, J¼15.3 Hz),
6.00 (2H, m), 6.62 (1H, d, J¼1.5 Hz), 6.73 (1H, d, J¼9.6 Hz), 6.97 (1H,
d, J¼6.9 Hz), 7.23 (3H, m), 7.59 (1H, s), 7.65 (1H, d, J¼6.9 Hz), 7.76
a
¼76.52(1)ꢁ,
b
¼79.99(1)ꢁ,
g
¼71.60(1)ꢁ, cell volume V¼617.9(1) Å3,
(1H, s), 8.01 (1H, d, J¼9.6 Hz); 13C NMR (75 MHz, CDCl3)
d
46.9
formula units/cell Z¼2, X-ray density rx¼1.415 g cmꢀ3
,
(CH2), 77.0 (CH2), 112.3 (CH), 112.5 (CH), 119.0 (C), 120.7 (CH), 122.3
(CH), 125.4 (CH), 126.8 (C), 128.0 (CH), 128.2 (CH), 128.8 (C), 132.5
(CH), 134.5 (C), 134.9 (CH), 135.4 (C), 135.7 (C), 142.0 (C), 142.9 (CH),
148.2 (C), 162.5 (C). HRMS [ESI], m/z calcd for C21H14ClNO3Na:
[MþNa]þ 386.0560; found: 386.0550.
2
qmax¼129.94ꢁ. Total/independent number of reflections 2282/
2099, Rint¼0.011, Rs¼0.011, unobserved (Fo<4
s (Fo)) 183, linear ab-
sorption coeff.
m
¼7.5 cmꢀ1. After convergence of refinements
R1¼0.051, Rw¼0.152, GoF¼1.15.
Acknowledgements
4.3.10. Compound 6e
White solid. Mp 124–126 ꢁC; Rf (60% pet. ether–chloroform)
We thank to the Council of Scientific and Industrial Research for
fellowships to K.B.S., A.H., P.P., P.S., S.N., R.P.. We are also thankful to
Dr. B. Achari, Emeritus Scientist, CSIR, for his valuable suggestions.
0.60; IR (KBr, cmꢀ1 3433, 1660, 1583, 1445, 1421; 1H NMR
) n
(600 MHz, CDCl3)
d
4.63 (1H, d, J¼15.0 Hz), 5.43 (1H, d, J¼15.0 Hz),
5.94 (1H, d, J¼13.2 Hz), 6.25 (1H, d, J¼13.8 Hz), 6.75 (1H, d,
J¼9.6 Hz), 6.86 (1H, d, J¼7.2 Hz), 7.17 (1H, dt, J¼1.2, 7.8 Hz), 7.22 (1H,
t, J¼7.2 Hz), 7.36 (1H, s), 7.47 (1H, dd, J¼3.0, 4.8 Hz), 7.51 (1H, dd,
J¼1.2, 4.8 Hz), 7.55 (1H, d, J¼7.8 Hz), 7.71 (1H, m), 8.00 (1H, d,
Supplementry data
1H and 13C NMR spectra of all new compounds associated with
this article can be found in the online version. Crystallographic data
in CIF format are available free of charge via the Internate at CCDC
704566/704567 contains the supplementary crystallographic data
for this paper. These data can be obtained free of charge via
www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cambridge
Crystallographic Data Centre, 12, Union Road, Cambridge CB2 1EZ,
UK; fax: þ44 1223 336033; or deposit@ccdc.cam.ac.uk). Supple-
mentary data associated with this article can be found in the online
version, at doi:10.1016/j.tet.2009.06.061.
J¼9.6 Hz); 13C NMR (150 MHz, CDCl3)
d 46.2 (CH2), 76.3 (CH2), 119.4
(C), 122.5 (CH), 124.6 (CH), 124.8 (CH), 125.7 (CH), 125.9 (CH), 128.2
(CH), 128.24 (CH), 128.3 (CH), 128.5 (C), 132.4 (CH), 133.0 (C), 134.6
(C), 134.8 (CH), 135.7 (C), 135.8 (C), 136.6 (C), 142.6 (C), 162.5 (C).
HRMS [ESI], m/z calcd for C21H14 ClNO2SNa: [MþNa]þ 402.0331;
found: 402.0330.
4.4. X-ray experiments, structure determination and
refinements
X-ray data collection for 3c was carried out on a Huber four
References and notes
circle diffractometer (Mo
monochromator) equipped with a Bruker APEX CCD area detector.
A total of 47,419 reflections (2
each with 600 frames in
K
a
radiation,
l
¼0.7107 Å, graphite
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q
ꢃ61.6ꢁ) were measured in six runs,
4
increments of 0.3ꢁ. Integration and
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merging with SAINT and XPREP, absorption correction with
SADABS.26 Structure solution (program SIR 200227) and refinement
(SHELXL28) ran routinely. C, N, O and Br atoms were refined an-
isotropically, isotropic displacement parameters were assigned to
the hydrogens, which were put into calculated positions according
to steric considerations. The asymmetric unit consist of two
[C17H12NO1Br2]þ cations, two Brꢀ anions and two water molecules.
The water hydrogens were not determined.
X-ray data collection for 4a was carried out on a Stoe four circle
diffractometer (Ni-filtered Cu K
with point detector within a hemisphere of reciprocal space
a
radiation,
l
¼1.5418 Å) equipped
(2
q
ꢃ130ꢁ) in the
u-2q-scan modus with variable scan range and
variable scan speed. 2 Standard reflections measured every 90 min
showed no significant variations during the data collection.
Structure solution and refinement (programs SIR 200227 and
SHELXL28) ran routinely. C, N and O atoms were refined aniso-
tropically, isotropic displacement parameters were assigned to the
hydrogens, which could all be located from a difference synthesis.
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4.4.1. Crystal data for 3c
[C17H12N1O1Br2]þꢂBrꢀꢂH2O, Mr¼504.01, brown block shaped
crystalswere grownfromCH3OH/MeCN. Dimensionsofthespecimen
used for X-ray experiments 0.70ꢂ0.55ꢂ0.30 mm. Space group
monoclinic P21/c. Lattice constants (Å) a¼16.356(3), b¼26.542(5),
c¼7.774(2),
b
¼93.12(3)ꢁ, cellvolume V¼3369.9(12) Å3, formulaunits/
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cell Z¼8, X-ray density rx¼1.979 g cmꢀ3, 2qmax¼61.58ꢁ. Number of

K.B. Sahu et al. / Tetrahedron 65 (2009) 6941–6949
6949
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