N-{4-Bromo-2-[(3-bromo-1-phenyl-sulfonyl-1H-indol-2-yl)methyl]-5-methoxy phenyl}acetamide

Article abstract of DOI:10.1107/S0108270103001410

In the title compound, C₂₄H₂₀Br₂N₂O₄S, the indole ring system is planar and the S atom has a distorted tetrahedral configuration. The sulfonyl-bound phenyl ring is orthogonal to the indole ring system and the conformation of the phenylsulfonyl substituent with respect to the indole moiety is influenced by intramolecular C-H...O hydrogen bonds involving the two sulfonyl O atoms. The mean plane through the acetylamido group makes a dihedral angle of 57.0 (1)° with the phenyl ring of the benzyl moiety. In the crystal, glide-related molecules are linked together by N-H...O hydrogen bonds and C-H...π interactions to form molecular chains, which extend through the crystal. Inversion-related chains are interlinked by C-H...π interactions to form molecular layers parallel to the bc plane. These layers are interconnected through π-π interactions involving the five- and six- membered rings of the indole moiety.

Full text of DOI:10.1107/S0108270103001410

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
amide is reported to be a highly potent non-nucleoside inhi-
bitor of HIV-1 reverse transcriptase (Williams et al., 1993).
Indole derivatives also exhibit antitumour activities (Andreani
et al., 2001; Bradlow et al., 1999; Cirrincione et al., 1999; Tiwari
et al., 1994; Dashwood et al., 1994). Some of the indole alka-
loids extracted from plants possess interesting cytotoxic,
antitumour and antiparasitic properties (Quetin-Leclercq,
1994; Mukhopadhyay et al., 1981). In view of this wide range of
biological activities associated with indole derivatives, we have
undertaken the X-ray structure analysis of the title compound,
(I), in order to study its conformation in the solid state.
ISSN 0108-2701
N-{4-Bromo-2-[(3-bromo-1-phenyl-
sulfonyl-1H-indol-2-yl)methyl]-
5-methoxyphenyl}acetamide
T. Ravishankar,a K. Chinnakali,b² N. Arumugam,c P. C.
Srinivasan,d Anwar Usmane and Hoong-Kun Fune*
aDepartment of Physics, Deen Dayal Engineering College, Kunnavalam 600 210,
Thiruvallur District, Tamil Nadu, India, bDepartment of Physics, Anna University,
Chennai 600 025, India, cR&D Department, Amrutanjan Ltd, Chennai 600 004,
India, dDepartment of Organic Chemistry, University of Madras, Guindy Campus,
Chennai 600 025, India, and eX-ray Crystallography Unit, School of Physics,
Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
Correspondence e-mail: hkfun@usm.my
In compound (I), the indole ring system is planar, with atom
Ê
C4 deviating by a maximum of 0.022 (4) A from the weighted
least-squares plane through that ring; the dihedral angle
formed by the planes of the benzene and pyrrole rings is
Received 6 January 2003
Accepted 16 January 2003
Online 18 February 2003
Ê
1.0 (2) A. The angles at the fused benzene ring of the indole
moiety show the same trend as that observed by Benassi et al.
(1991) in benzocyclopentanes (average values given in square
brackets): C8ÐC3ÐC4 120.2 (3) and C3ÐC8ÐC7 121.4 (3)ꢀ
[ꢁ 120.6 (6)ꢀ], C3ÐC4ÐC5 118.4 (4) and C8ÐC7ÐC6
116.5 (4)ꢀ [ꢂ 118.6 (2)ꢀ], C4ÐC5ÐC6 120.9 (4) and C5ÐC6Ð
C7 122.6 (4)ꢀ [ꢃ 120.8 (2)ꢀ], C2ÐC3ÐC8 106.6 (3) and N1Ð
C8ÐC3 107.3 (3)ꢀ [" 110.4 (1)ꢀ], and C2ÐC3ÐC4 133.2 (3)
and N1ÐC8ÐC7 131.3 (3)ꢀ [ꢄ 128.9 (4)ꢀ].
In the title compound, C24H20Br2N2O4S, the indole ring
system is planar and the S atom has a distorted tetrahedral
con®guration. The sulfonyl-bound phenyl ring is orthogonal to
the indole ring system and the conformation of the phenyl-
sulfonyl substituent with respect to the indole moiety is
in¯uenced by intramolecular CÐHÁ Á ÁO hydrogen bonds
involving the two sulfonyl O atoms. The mean plane through
the acetylamido group makes a dihedral angle of 57.0 (1)ꢀ with
the phenyl ring of the benzyl moiety. In the crystal, glide-
related molecules are linked together by NÐHÁ Á ÁO hydrogen
bonds and CÐHÁ Á Áꢀ interactions to form molecular chains,
which extend through the crystal. Inversion-related chains are
interlinked by CÐHÁ Á Áꢀ interactions to form molecular layers
parallel to the bc plane. These layers are interconnected
through ꢀ±ꢀ interactions involving the ®ve- and six-
membered rings of the indole moiety.
As observed in other related structures (Yokum &
Fronczek, 1997; Sankaranarayanan et al., 2000), atom N1 is
slightly out of the plane de®ned by atoms S1, C1 and C8
2
Ê
[deviation 0.141 (2) A]. The NÐCsp bond lengths, viz. N1Ð
Ê
C1 [1.423 (4) A] and N1ÐC8 [1.422 (4) A], are longer than
Ê
the mean value reported for atoms with planar
N
Ê
Ê
[1.355 (14) A] and pyramidal [1.416 (18) A] con®gurations
(Allen et al., 1987). This bond-length increase may be a result
of the electron-withdrawing character of the phenylsulfonyl
group.
Atom S1 has a distorted tetrahedral con®guration, with the
angles O2ÐS1ÐO1 [120.1 (2)ꢀ] and N1ÐS1ÐC9 [104.5 (1)ꢀ]
deviating signi®cantly from ideal tetrahedral values. Similar
distortions in the sulfonyl group have been reported and are
Comment
Indole derivatives have been found to exhibit interesting
antibacterial and antifungal properties (Wang & Ng, 2002;
Singh et al., 2000; Tsotinis et al., 1997; Quetin-Leclercq et al.,
1995). Polyhalogenated indole derivatives exhibit marked
antimicrobial activity against Gram-positive and Gram-nega-
tive bacteria and fungi (Piscopo, Diurno, Mazzoni, Ciaccio &
Veneruso, 1990; Piscopo, Diurno, Mazzoni & Ciaccio, 1990).
Pyrido[1,2-a]indole derivatives have been identi®ed as potent
inhibitors of human immunode®ciency virus type 1 (Taylor et
al., 1999), and 5-chloro-3-(phenylsulfonyl)indole-2-carbox-
attributed to the repulsive interaction between the short S
O
bonds (Sankaranarayanan et al., 2001; Seshadri et al., 2002).
The conformation of the phenylsulfonyl group with respect to
the indole moiety is described by the torsion angles O1ÐS1Ð
N1ÐC1 [36.3 (3)ꢀ], O2ÐS1ÐN1ÐC8 [ 35.2 (3)ꢀ] and N1Ð
S1ÐC9ÐC10 [116.1 (3)ꢀ]. This conformation is in¯uenced by
the intramolecular CÐHÁ Á ÁO hydrogen bonds, C7ÐH7Á Á ÁO2
and C15ÐH15AÁ Á ÁO1, involving sulfonyl atoms O1 and O2,
which lie almost in the plane of the indole system (Fig. 1 and
Table 2). The sulfonyl-bound phenyl ring is orthogonal to the
² Additional correspondence author, email: kali@annauniv.edu.
Acta Cryst. (2003). C59, o137±o140
DOI: 10.1107/S0108270103001410
# 2003 International Union of Crystallography o137

organic compounds
Figure 1
The molecular structure of (I), showing the intramolecular interactions
(dashed lines). Displacement ellipsoids are drawn at the 50% probability
level and H atoms are shown as small spheres of arbitrary radii.
Figure 2
A view of the molecular network of (I) down the a axis. For clarity, only
the H atoms involved in the hydrogen bonds (dashed lines) are shown.
indole ring system, forming a dihedral angle of 89.09 (8)ꢀ. The
SÐN, SÐO and SÐC distances are comparable with the
values reported for related phenylsulfonylindoles (Sankara-
narayanan et al., 2001; Seshadri et al., 2002)
interactions involving atom C22 and the phenyl ring of the
3
The conformation of the attachment of the benzyl substi-
tuent to the indole ring system is described by the N1ÐC1Ð
C15ÐC16 torsion angle of 85.9 (3)ꢀ; the C1ÐC15ÐC16ÐC17
torsion angle of 38.6 (4)ꢀ shows how the phenyl ring of the
benzyl moiety is oriented. The mean plane through the
acetylamido group makes a dihedral angle of 57.0 (1)ꢀ with the
phenyl ring of the benzyl moiety. The low value [10.1 (5)ꢀ] of
the C20ÐC19ÐO3ÐC22 torsion angle is in agreement with
the tendency shown by the methoxy group to be coplanar with
phenyl, as is usually seen in all the anisoles (Domiano et al.,
1979). The sum of the angles around atom N2 is 360ꢀ, indi-
cating sp2 hybridization. The N2ÐC21 bond length of
benzyl moiety of the symmetry-related molecule at (x,
z
y,
2
12). Neighbouring inversion-related chains are interlinked
by CÐHÁ Á Áꢀ interactions involving atom C12 and the benzene
ring of the indole moiety at ( x, 1 y, z), to form layers
parallel to the bc plane (Fig. 2). This interaction results in the
formation of centrosymmetrically CÐHÁ Á Áꢀ-bonded dimeric
pairs (Table 2). Since the sulfonyl phenyl ring is orthogonal to
the indole moiety, the benzene ring of the indole moiety and
the symmetry-related phenyl rings are arranged to form a
T-shaped structure, with their centroids separated by
3
Ê
1.420 (4) A is closer to the average CarÐNsp (pyramidal)
2
value of 1.419 (17) A than to the CarÐNsp (planar) value of
Ê
Ê
1.353 (7) A (Allen et al., 1987). This is probably due to some
lack of accuracy in the previous data, while the lack of ꢀ
conjugation of the N atom with the phenyl ring is indicated by
the lack of coplanarity of the acetylamido group and the
phenyl ring of the benzyl moiety. The mean planes through the
phenyl rings of the benzyl and phenylsulfonyl groups are tilted
by 28.7 (1)ꢀ and the centroids of these rings are separated by
Ê
4.095 (2) A, indicating the absence of ꢀ±ꢀ interactions.
However, a weak intramolecular CÐHÁ Á Áꢀ interaction is
observed between these rings, with atoms C10 and H10
separated from the centroid of the phenyl ring of the benzyl
Ê
moiety by 3.244 (4) and 2.92 A, respectively, with the angle
subtended at atom H10 being 102ꢀ.
In the crystal of (I), glide-related molecules are linked
together by NÐHÁ Á ÁO hydrogen bonds (Table 2) to form
molecular chains which extend through the crystal. The
molecular chain structure is further stabilized by CÐHÁ Á Áꢀ
Figure 3
A view of the CÐHÁ Á Áꢀ hydrogen-bonded dimers and ꢀ±ꢀ interactions
in (I).
ꢁ
o138 T. Ravishankar et al.
C24H20Br2N2O4S
Acta Cryst. (2003). C59, o137±o140

organic compounds
Ê
5.123 (2) A. This distance is slightly larger than the separation
Data collection
Ê
of 5.10 A reported for normal T-shaped ꢀ±ꢀ-stacking inter-
Siemens SMART CCD area-
detector diffractometer
! scans
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
Tmin = 0.343, Tmax = 0.436
15 276 measured re¯ections
5984 independent re¯ections
3727 re¯ections with I > 2ꢇ(I)
Rint = 0.031
actions (Hobza et al., 1994). These dimeric pairs are packed
along the cell diagonal such that the indole moieties of the
(1 x, 1 y, 1 z) adjacent pairs face each other, with the
centroids of the ®ve- and six-membered rings separated by
3.769 (2) A, an indication for ꢀ±ꢀ interactions (Fig. 3). In
addition to these interactions, a short intermolecular contact
ꢅmax = 28.3ꢀ
h = 13 ! 11
k = 33 ! 17
l = 12 ! 11
Ê
Re®nement
Re®nement on F2
R[F2 > 2ꢇ(F2)] = 0.041
wR(F2) = 0.097
S = 1.00
5984 re¯ections
w = 1/[ꢇ2(Fo2) + (0.0316P)2
+ 2.3420P]
Ê
of 3.247 (4) A is observed between atom Br1 and atom C13 of
the molecule translated one unit along the c axis.
where P = (Fo2 + 2Fc2)/3
(Á/ꢇ)max = 0.001
3
Ê
Áꢈmax = 0.85 e A
3
Ê
0.74 e A
301 parameters
H-atom parameters constrained
Áꢈmin
=
Extinction correction: SHELXTL
(Sheldrick, 1997)
Extinction coef®cient: 0.0023 (3)
Experimental
To a solution of [3-bromo-1-(phenylsulfonyl)indol-2-yl]methanol
(3.6 g, 10 mmol) in chloroform (200 ml) was added a solution of
4-bromo-3-methoxyacetanilide (2.34 g, 10 mmol) in the same solvent
(25 ml), followed by anhydrous magnesium sulfate (10 g) and boron
tri¯uoride etherate (2.0 ml). The resulting solution was re¯uxed for
3 h. Water (100 ml) was then added, and the organic layer was
separated and washed with 20% hydrochloric acid (1 Â 50 ml),
followed by washing with water and saturated bicarbonate solution.
The solvent was removed by distillation after drying over anhydrous
sodium sulfate. The residue was chromatographed on a silica-gel
column (350 mesh) and eluted successively with 20% ethyl acetate in
hexane, followed by 25% and then ®nally with 30%. The 30% ethyl
acetate in hexane eluant gave 2-arylmethylindole, which was then
crystallized from hexane±chloroform (2:1) to give crystals of (I) (m.p.
455±457 K).
Table 2
Hydrogen-bonding geometry (A, ).
ꢀ
Ê
Cg1 and Cg2 denote the centroids of the C3±C8 and C16±C21 rings,
respectively.
DÐHÁ Á ÁA
DÐH
HÁ Á ÁA
DÁ Á ÁA
DÐHÁ Á ÁA
C7ÐH7Á Á ÁO2
0.93
0.93
0.97
0.97
0.97
0.86
0.93
0.96
0.93
2.35
2.50
2.34
2.50
2.89
2.05
2.92
2.85
2.88
2.928 (5)
2.886 (5)
2.886 (4)
2.936 (4)
3.346 (3)
2.843 (3)
3.244 (5)
3.661 (6)
3.784 (5)
120
105
115
107
110
154
102
143
164
C10ÐH10Á Á ÁO1
C15ÐH15AÁ Á ÁO1
C15ÐH15AÁ Á ÁN2
C15ÐH15BÁ Á ÁBr1
N2ÐH2NÁ Á ÁO4i
C10ÐH10Á Á ÁCg2
C22ÐH22BÁ Á ÁCg2i
C12ÐH12Á Á ÁCg1ii
Symmetry codes: (i) x; 32 y; z 21; (ii) x; 1 y; z.
Crystal data
3
C24H20Br2N2O4S
Mr = 592.30
Dx = 1.620 Mg m
Mo Kꢁ radiation
Cell parameters from 4221
re¯ections
The H atoms were ®xed geometrically and allowed to ride on the
Ê
corresponding non-H atoms, with an NÐH distance of 0.86 A and
Ê
CÐH distances in the range 0.93±0.96 A. The isotropic displacement
Monoclinic, P21=c
Ê
a = 10.2647 (11) A
b = 24.976 (3) A
ꢅ = 2.3±25.0ꢀ
ꢆ = 3.46 mm
T = 293 (2) K
Ê
parameters were set equal to 1.5Ueq(C) for methyl H atoms and
1.2Ueq(C) for all other H atoms. Rotating group re®nement was used
for the methyl groups.
1
Ê
c = 9.7963 (11) A
ꢂ = 104.760 (2)ꢀ
3
Ê
V = 2428.6 (5) A
Z = 4
Block, colourless
0.34 Â 0.30 Â 0.24 mm
Data collection: SMART (Siemens, 1996); cell re®nement: SAINT
(Siemens, 1996); data reduction: SAINT; program(s) used to solve
structure: SHELXTL (Sheldrick, 1997); program(s) used to re®ne
structure: SHELXTL; molecular graphics: SHELXTL; software used
to prepare material for publication: SHELXTL, PARST (Nardelli,
1995) and PLATON (Spek, 2002).
Table 1
Selected geometric parameters (A, ).
ꢀ
Ê
S1ÐO2
S1ÐO1
S1ÐN1
S1ÐC9
O4ÐC23
1.419 (2)
1.425 (2)
1.675 (3)
1.759 (3)
1.221 (4)
N1ÐC8
N1ÐC1
N2ÐC23
N2ÐC21
1.422 (4)
1.423 (4)
1.350 (4)
1.420 (4)
TR thanks the authorities of Deen Dayal Engineering
College for their support. AU thanks Universiti Sains
Malaysia for a Visiting Postdoctoral Fellowship. HKF thanks
the Malaysian Government and Universiti Sains Malaysia for
research grant R&D No. 305/PFIZIK/610961.
O2ÐS1ÐO1
O2ÐS1ÐN1
O1ÐS1ÐN1
O2ÐS1ÐC9
O1ÐS1ÐC9
120.06 (15)
106.12 (15)
106.70 (13)
109.40 (15)
108.91 (16)
N1ÐS1ÐC9
C5ÐC6ÐC7
C6ÐC7ÐC8
C1ÐC15ÐC16
104.48 (14)
122.6 (4)
116.5 (4)
115.9 (2)
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: NA1592). Services for accessing these data are
described at the back of the journal.
O2ÐS1ÐN1ÐC8
O1ÐS1ÐN1ÐC8
O2ÐS1ÐN1ÐC1
O1ÐS1ÐN1ÐC1
O2ÐS1ÐC9ÐC14
O1ÐS1ÐC9ÐC14
35.2 (3)
164.4 (2)
165.4 (2)
36.3 (3)
49.4 (3)
177.6 (3)
O2ÐS1ÐC9ÐC10
O1ÐS1ÐC9ÐC10
N1ÐC1ÐC15ÐC16
C1ÐC15ÐC16ÐC17
C22ÐO3ÐC19ÐC20
130.6 (3)
2.4 (3)
85.9 (3)
38.6 (4)
10.1 (5)
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C24H20Br2N2O4S
Acta Cryst. (2003). C59, o137±o140