Synthesis and evaluation of antimicrobial and anthelmintic activity of novel fluorinated 7-ethyl-10H-phenothiazines, their sulphones and ribofuranosides

Article abstract of DOI:10.1007/s12039-013-0551-2

A series of novel fluorinated 10H-phenothiazines were synthesized via Smiles rearrangement. 10H-phenothiazines on refluxing with 30% hydrogen peroxide in glacial acetic acid gave 10H-phenothiazines- 5, 5-dioxides (sulphones). These synthesized 10H-phenothiazines were then used as base to prepare ribofuranosides by treating them with sugar (β-D-ribofuranosyl- 1-acetate-2, 3, 5-tribenzoate). The synthesized compounds were screened for antimicrobial activity and anthelmintic activity. The structural assignments of ompounds were made on the basis of spectroscopic data and elemental analysis. Indian Academy of Sciences.

Full text of DOI:10.1007/s12039-013-0551-2

c
J. Chem. Sci. Vol. 126, No. 1, January 2014, pp. 197–204. ꢀ Indian Academy of Sciences.
Synthesis and evaluation of antimicrobial and anthelmintic activity
of novel fluorinated 7-ethyl-10H-phenothiazines, their sulphones
and ribofuranosides
NAVEEN GAUTAMa,∗, ABHILASHA YADAVb, NISHIDHA KHANDELWALb and
D C GAUTAMb
aLBS Government PG College, Kotputli, Jaipur 303 108, India
bDepartment of Chemistry, University of Rajasthan, JLN Marg, Jaipur 302 004, India
e-mail: ngautam70@yahoo.co.in; abhilashasuraj@gmail.com; nishidha.khandelwal@gmail.com;
drdcgautam@yahoo.co.in
MS received 9 November 2012; revised 30 September 2013; accepted 4 October 2013
Abstract. A series of novel fluorinated 10H-phenothiazines were synthesized via Smiles rearrangement.
10H-phenothiazines on refluxing with 30% hydrogen peroxide in glacial acetic acid gave 10H-phenothiazines-
5, 5-dioxides (sulphones). These synthesized 10H-phenothiazines were then used as base to prepare ribo-
furanosides by treating them with sugar (β-D-ribofuranosyl- 1-acetate-2, 3, 5-tribenzoate). The synthesized
compounds were screened for antimicrobial activity and anthelmintic activity. The structural assignments of
compounds were made on the basis of spectroscopic data and elemental analysis.
Keywords. 10H-phenothiazines; Smiles rearrangement; sulphones; ribofuranosides; antimicrobial activity;
anthelmintic activity.
1. Introduction
2. Experimental
A large number of publications and patents registered By thin-layer chromatography purity of compounds
worldwide gave much emphasis on the synthesis of was checked using silica gel ‘G’ as adsorbent, visu-
10H-phenothiazine derivatives.1–7 They possess wide alizing these by ultraviolet light or in an iodine
range of biological, medicinal and industrial applica- chamber. All the melting points were determined in
tions. These moieties are widely used as antiviral, anti- open capillary tubes and are uncorrected. IR spec-
malarial, antiinflammatory, anticancer, antituberclosis, tra were recorded in KBr on SHIMADZU 8400 S
central nervous system (CNS) activity. The folding FTIR spectrophotometer. Mass spectra were recorded
along nitrogen and sulphur axis in 10H-phenothiazine on WATERS (micro mass MS technologies) Q-T by
is a significant factor for biological activities.8–14 It electron spray ionization. 1H NMR and 13C NMR spec-
has stimulated our interest to convert phenothiazines to tra were recorded on JEOL AL 300 spectrometer at fre-
sulphones, to understand oxidation behaviour of 10H- quencies of 300.40 MHz and 75.45 MHz, respectively
phenothiazine and to investigate changes in infra-red in Me2SO-d6/CDCl3 using TMS (tetramethyl silane) as
and nuclear magnetic resonance spectra caused by the an internal standard. 19F NMR spectra were recorded in
conversion of sulphide linkage to sulphones. Besides CDCl3 using CF3COOH as standard compound.
this, ribofuranosides of 10H-phenothiazines have also
2.1 General procedure for the synthesis
of 1-nitro-10H-phenothiazines (5a)
been reported to possess biological activities. In the
preparation of ribofuranosides, ribosylation takes place
mostly by replacing hydrogen atom attached to nitrogen
4-Chloro-3, 5-dinitrobenzotrifluoride (2a) was added
in phenothiazines.
to a stirred suspension of 2-amino-5-ethylbenzenethiol
(1a) (0.01 mol), NaOH (0.01 mol) and 20 mL absolute
alcohol in round bottom flask. A reflux condenser was
fitted in the round bottom flask. The reaction contents
were refluxed for 2 h then concentrated, cooled and
filtered. The precipitate was washed well with hot H2O
∗For correspondence
and 20% EtOH and crystallized from Me2CO.
197

198
Naveen Gautam et al.
2.1a 7- Ethyl-3-trifluoromethyl-1-nitro-10H-pheno- for 4 h. The contents were then poured into a crushed
thiazine (5a): Orange solid; m.p. : 78◦C–80◦C, Yield ice containing beaker. The solid separated out was fil-
: 64% ; IR (KBr) : v 3360 (N–H), 1540 and 1320 (-NO2 tered, washed with cold H2O and finally with 30%
1
str.), 1330 and 1150 (–CF3), 1075 (C-S); H NMR EtOH and then crystallized from C6H6.
spectral data (300.40 MHz, Me2SO-d6, δ ppm from
TMS) : δ 8.46 (s, 1H, N-H), 7.29–6.34 (m, 5H, Ar-H),
2.72 (q, 2H, 3JHH = 7.5 Hz, CH2 of C2H5 at C7), 1.42
2.4a 7- Ethyl-1-trifluoromethyl-3-nitro-10H-pheno-
(t, 3H, 3JHH = 7.0 Hz, CH3 of C2H5 at C7); 13C NMR
thiazine (5b): Dark orange solid; m.p. : 85◦C–87◦C,
(75.45 MHz, CDCl3, δ ppm from TMS) : δ 138.70 (C-
1), 118.0 (C-2), 121.9 (C-3), 130.6 (C-4), 128.8 (C-6),
129.0 (C-7), 127.0 (C-8), 119.1 (C-9), 120.0 (C-4a),
118.9 (C-5a), 139.4 (C-9a), 144.0 (C-10a), 31.9 (CH2of
C2H5 at C7), 14.4 (CH3 of C2H5 at C7), 122.1 (CF3
Yield : 87% ; IR (KBr) : v 3400 (N–H), 1580,1370
(-NO2 str.), 1370 and 1190 (–CF3), 1073 (C-S) and;
1H NMR spectral data (300.40 MHz, Me2SO-d6, δ
ppm from TMS) : δ 8.25 (s, 1H, N-H), 7.36–6.81
3
(m, 5H, Ar-H), 2.60 (q, 2H, JHH = 7.4 Hz, CH2
1
at C3, q, JCF = 271.00 Hz);19F NMR (282.65 MHz,
3
of C2H5 at C7), 1.29 (t, 3H, JHH = 6.8 Hz, CH3
of C2H5 at C7) ; 13C NMR (75.45 MHz, CDCl3, δ
ppm from TMS) : δ 138.50 (C-1), 118.8 (C-2), 122.1
(C-3), 131.2 (C-4), 127.9 (C-6), 128.6 (C-7), 127.1
(C-8), 118.5 (C-9), 120.3 (C-4a), 118.2 (C-5a), 139.0
CDCl3) : δ –62.01 (s, 3F, CF3); MS (FAB) 10 kV, m/z
(rel. int.) : 340 (M+) (100), 323 [M–OH]+ (60), 310
[M–NO]+ (65), 294 [M–NO2]+ (40), 293 [M–HNO2]+
(50) etc.; Anal. Calcd for C15H11N2O2F3S: C, 52.94; H,
3.23; N, 8.23. Found : C, 52.64; H, 3.15; N, 8.75.
(C-9a), 148.0 (C-10a), 31.0 (CH2of C2H5 at C7), 14.7
1
(CH3 of C2H5 at C7), 122.8 (CF3 at C1, q, JCF
=
270.80 Hz);19F NMR (282.65 MHz, CDCl3) : δ –61.99
(s, 3F, CF3); MS (FAB) 10 kV, m/z (rel. int.) : 340
(M+) (100), 339 [M –H]+ (68), 311 [M–CH2CH3]+
(50),175 [M–C5H2NO2F3]+ (40) etc; Anal. Calcd for
C15H11N2O2F3S : C, 52.94; H, 3.23; N, 8.23. Found :
C, 53.12; H, 3.30; N, 8.35.
2.2 General procedure for the synthesis
of 2-amino-2ꢁ-nitrodiphenylsuphides (3b–d)
In a 50 mL round bottom flask, 2-amino-5-ethylben-
zenethiol (1a) (0.01 mol), which was dissolved in
20 mL EtOH, was added to anhydrous NaOAc
(0.01 mol) and halonitrobenzenes (2b–d) (0.01 mol)
(dissolved in 10 mL EtOH). The reaction mixture was
refluxed for 4–5 h, concentrated in an ice chamber
overnight. The precipitate separated out was filtered,
washed with 30% EtOH and recrystallised from MeOH.
2.4b 7-
Ethyl-3-fluoro-10H-phenothiazine
(5c):
Brown solid; m.p. : 87◦C–90◦C, Yield : 55% ; IR (KBr)
1
: v 3330 (N–H), 1078 (C-S) and 1105 (C-F str. ); H
NMR spectral data (300.40 MHz, Me2SO-d6, δ ppm
from TMS) : δ 8.27 (s, 1H, N–H), 7.87–6.53 (m, 6H,
3
2.3 General procedure for the synthesis
Ar-H), 2.59 (q, 2H, JHH = 7.5 Hz, CH2of C2H5 at
of 2-formamido-2ꢁ-nitrodiphenylsulphides (4b–d)
3
C7), 1.48 (t, 3H, JHH = 6.9 Hz, CH3 of C2H5 at C7);
13C NMR (75.45 MHz, CDCl3, δ ppm from TMS) :
The 2-amino-2ꢁ-nitrodiphenylsulphides (3b–d) (0.01
mol) obtained was refluxed for 4 h in 90% HCOOH
(20 mL) in a round bottom flask. The contents were
then poured into a beaker containing crushed ice and a
solid that separated out was filtered, washed with H2O
until the filtrate was neutralized and recrystallised from
C6H6.
1
δ 121.40 (C-1), 114.2 (C-2), 152.5 (C-3, d, JCF
=
249.4 Hz), 117.6 (C-4), 128.3 (C-6), 126.7 (C-7),
127.2 (C-8), 119.9 (C-9), 120.5 (C-4a), 118.6 (C-5a),
138.8 (C-9a), 138.2 (C-10a), 30.8 (CH2of C2H5 at C7),
14.0 (CH3 of C2H5 at C7);19F NMR (282.65 MHz,
CDCl3) : δ–109.50 (s, 1F, C–F); MS (FAB) 10 kV, m/z
(rel. int.) : 245 (M+) (100), 244 [M –H]+ (40), 216
[M–CH2CH3]+ (70), 175 [M–C4H3F]+ (50) etc; Anal.
Calcd for C14H12NFS : C, 68.57; H, 4.89; N, 5.71.
Found : C, 68.33; H, 4.90; N, 5.67.
2.4 General procedure for the synthesis
of 10H-phenothiazines (5b–d)
10H-phenothiazines15 synthesized by formyl deriva-
tives via Smiles rearrangement. Formyl derivatives 2.4c 2-Chloro-7-ethyl- 3-trifluoromethyl -10H-pheno-
(4b–d) (0.01 mol) in Me2CO (15 mL) were added to thiazine (5d): Red solid; m.p. : 90◦C–93◦C, Yield
alcoholic solution of KOH (0.2 g in 5 mL EtOH). The : 79% ; IR (KBr) : v 3190 (N–H), 1300 and 1160
1
contents were refluxed for 30 min. To this a second lot (–CF3), 1080 (C-S) and 810 cm−1 (C–Cl); H NMR
of KOH (0.2 g in 5 mL EtOH) was added and refluxed spectral data (300.40 MHz, Me2SO-d6, δ ppm from

Synthesis, biological activity of fluorinated 7-ethyl-10H-phenothiazines
199
TMS) : δ 8.42 (s, 1H, N-H), 7.26–6.73 (m, 5H, Ar- 2.5b 7- Ethyl -1-trifluoromethyl -3-nitro-10H-pheno-
3
H), 2.53 (q, 2H, JHH = 7.4 Hz, CH2 of C2H5 at C7), thiazine -5,5-dioxide (6b): Brown solid; m.p. : 220◦C,
3
1.25 (t, 3H, JHH = 6.8 Hz, CH3 of C2H5 at C7) ; yield : 59%, IR (KBr) : v 3410 (N–H), 1570 and 1390
13C NMR (75.45 MHz, CDCl3, δ ppm from TMS) : (-NO2 str.), 1390 and 1195 (–CF3), 1175 and 1158 (SO2
δ 119.20 (C-1), 128.9 (C-2), 118.5 (C-3), 126.9 (C- sym), 588 and 570 (SO2 bend), 1344, 1300 and 1260
1
4), 129.8 (C-6), 127.8 (C-7), 126.4 (C-8), 119.4 (C- (SO2 asym), and 1085 cm−1 (C–S); H NMR spec-
9), 117.4 (C-4a), 118.4 (C-5a), 140.0 (C-9a), 146.9 (C- tral data (300.40 MHz, Me2SO-d6, δ ppm from TMS)
10a), 31.6 (CH2of C2H5 at C7), 14.4 (CH3 of C2H5 : δ 8.50 (s, 1H, N-H), 7.56–6.90 (m, 5H, Ar-H), 2.90
1
3
at C7), 115.1 (CF3 at C3, q, JCF = 270.00 Hz);19F (q, 2H, JHH = 7.4 Hz, CH2of C2H5 at C7), 1.30 (t,
NMR (282.65 MHz, CDCl3) : δ –62.32 (s, 3F, CF3); 3H, JHH = 6.8 Hz, CH3 of C2H5 at C7); 13C NMR
3
MS (FAB) 10 kV, m/z (rel. int.) : 329 (M+) (100), 331 (75.45 MHz, CDCl3, δ ppm from TMS) : δ 139.0 (C-
(M+2) (32), 328 [M –H]+ (45), 300 [M–CH2CH3]+ 1), 126.3 (C-2) 122.3 (C-3), 130.9 (C-4), 127.5 (C-6),
(60), 175 [M–C5H2F3Cl]+ (50) etc; Anal. Calcd for 130.8 (C-7), 133.7 (C-8), 120.4 (C-9), 125.2 (C-4a),
C15H11NClF3S : C, 54.62; H; 3.34; N, 4.24. Found : C, 123.9 (C-5a), 138.3 (C-9a), 144.0 (C-10a), 32.1 (CH2of
54.85, H, 3.41; N, 4.32.
C2H5 at C7), 14.5(CH3 of C2H5 at C7), 123.1 (CF3 at C1,
q, 1JCF = 270.50 Hz);19F NMR (282.65 MHz, CDCl3)
: δ –61.96 (s, 3F, CF3); MS (FAB) 10 kV, m/z (rel. int.)
: 372 (M+) (100), 371 [M–H]+ (48), 308 [M–SO2]+
(56), 281 [M–SO2–HCN]+ (40) etc; Anal. Calcd for
C15H11N2O4F3S : C, 48.38; H, 2.95; N, 7.52, Found : C,
48.60; H, 3.01; N, 7.66.
2.5 General procedure for the synthesis
of 10H-phenothiazines-5,5-dioxides (sulphones) (6a–d)
In round bottom flask a mixture of substituted phe-
nothiazines (5a–d) (0.01 mol), glacial HOAc (20 mL)
and 5 mL of 30% H2O2 were refluxed for 15 min
at 50–60◦C. Heating was stopped and another lot of
H2O2 (5 mL) was added. The reaction mixture was
again refluxed for 4 h. The reaction contents were
then poured into a beaker containing crushed ice. The
residue obtained was filtered, washed with H2O and
crystallized from EtOH.
2.5c 7-Ethyl-3-fluoro-10H-phenothiazine-5,5-dioxide
(6c): Brown solid; m.p. : 190◦C, yield : 59%, IR
(KBr) : v 3340 (N–H), 1115 (C-F str. ), 1170 and 1144
(SO2 sym), 584 and 568 (SO2 bend), 1341, 1290 and
1
1260 (SO2 asym), and 1078 cm−1 (C–S); H NMR
spectral data (300.40 MHz, Me2SO-d6, δ ppm from
TMS) : δ 8.63 (s, 1H, N-H), 8.03–6.78 (m, 6H, Ar-H),
2.91 (q, 2H, 3JHH = 7.5 Hz, CH2 of C2H5 at C7), 1.50
(t, 3H, 3JHH = 6.9 Hz, CH3 of C2H5 at C7); 13C NMR
(75.45 MHz, CDCl3, δ ppm from TMS) : δ 121.2 (C-1),
2.5a 7- Ethyl -3-trifluoromethyl -1-nitro-10H-pheno-
thiazine-5,5-dioxide (6a): Dark yello solid; m.p. :
90◦C ; Yield : 67%, IR (KBr) : v 3390 (N–H), 1550 and
1340 (-NO2 str.), 1320 and 1170 (–CF3), 1180 and 1160
(SO2 sym), 585 and 567 (SO2 bend), 1340, 1301 and
1265 (SO2 asym), and 1085 cm−1 (C–S); 1H NMR spec-
tral data (300.40 MHz, Me2SO-d6, δ ppm from TMS)
: δ 8.96 (s, 1H, N-H), 7.49–6.60 (m, 5H, Ar-H), 2.88
1
121.0 (C-2), 153.5 (C-3, d, JCF = 249.1 Hz), 115.7
(C-4), 127.8 (C-6), 130.7 (C-7), 133.1 (C-8), 120.4
(C-9), 125.5 (C-4a), 123.5 (C-5a), 138.1 (C-9a), 137.0
(C-10a), 32.6 (CH2of C2H5 at C7), 14.4 (CH3 of C2H5
at C7);19F NMR (282.65 MHz, CDCl3) : δ –109.34 (s,
1F, C–F); MS (FAB) 10 kV, m/z (rel. int.) : 277 (M+)
(100), 276 [M–H]+ (55), 213 [M–SO2]+ (35), 186 [M–
SO2–HCN]+ (50) etc; Anal. Calcd for C14H12NO2FS :
C, 60.64; H, 4.33; N, 5.05, Found : C, 60.96; H, 4.42;
N, 4.96.
3
(q, 2H, JHH = 7.5 Hz, CH2of C2H5 at C7), 1.61 (t,
3
3H, JHH = 7.0 Hz, CH3 of C2H5 at C7); 13C NMR
(75.45 MHz, CDCl3, δ ppm from TMS) : δ 138.9 (C-
1), 125.9 (C-2),122.6 (C-3), 130.7 (C-4), 127.7 (C-6),
130.1 (C-7), 133.4 (C-8), 120.3 (C-9), 124.4 (C-4a),
123.8 (C-5a), 138.8 (C-9a), 140.0 (C-10a), 33.9 (CH2of 2.5d 2-Chloro-7-ethyl- 3-trifluoromethyl -10H-pheno-
C2H5 at C7), 14.6 (CH3 of C2H5 at C7), 114.5 (CF3 thiazine-5,5-dioxide (6d): Dark red solid; m.p. :
1
at C3,q, JCF = 270.70 Hz);19F NMR (282.65 MHz, 150◦C ; Yield : 62%, IR (KBr) : v 3210 (N–H), 1310
CDCl3) : δ –62.26 (s, 3F, CF3); MS (FAB) 10 kV, and 1180 (–CF3), and 830 cm−1 (C–Cl), 1180 and 1155
m/z (rel. int.) : 372 (M+) (100), 355 [M–OH]+ (60), (SO2 sym), 575 and 553 (SO2 bend), 1339, 1288 and
342 [M–NO]+ (48), 326 [M–NO2]+ (72), 325 [M– 1265 (SO2 asym), and 1090 cm−1 (C–S); 1H NMR spec-
HNO2]+ (51), 308 [M–SO2]+ (47) etc; Anal. Calcd for tral data (300.40 MHz, Me2SO-d6, δ ppm from TMS)
C15H11N2O4F3S : C, 48.38; H, 2.95; N, 7.52, Found : C, : δ 9.10 (s, 1H, N-H), 7.30–6.90 (m, 5H, Ar-H), 2.80
3
48.52; H, 2.99; N, 7.45.
(q, 2H, JHH = 7.4 Hz, CH2of C2H5 at C7), 1.40 (t,

200
Naveen Gautam et al.
[M–OH]+ (80), 755 [M–NO]+ (40), 739 [M–NO2]+
(40), 738 [M–HNO2]+ (55) etc.; Anal. Calcd for
C41H31N2O9F3S: C, 62.75; H, 3.94; N, 3.56. Found : C,
62.98; H, 4.01; N, 3.64.
3
3H, JHH = 6.8 Hz, CH3 of C2H5 at C7); 13C NMR
(75.45 MHz, CDCl3, δ ppm from TMS) : δ 120.80
(C-1), 136.1 (C-2),119.5 (C-3), 126.1 (C-4), 128.3 (C-
6),130.4 (C-7), 133.2 (C-8), 120.0 (C-9), 122.6 (C-4a),
123.6 (C-5a), 138.2 (C-9a), 146.0 (C-10a), 32.6 (CH2of
C2H5 at C7), 14.9 (CH3 of C2H5 at C7), 115.6 (CF3
2.6b N-(2ꢁ,3ꢁ,5ꢁ-tri-O-benzoyl-β-D-ribofuranosyl)-
7-ethyl-1-trifluoromethyl-3-nitro-10H-phenothiazine
(7b): Red solid; m.p. : 98◦C–101◦C, Yield : 77%
; IR (KBr) : v 1590 and,1350 (-NO2 str.), 1340 and
at C3, q, JCF = 270.30 Hz);19F NMR (282.65 MHz,
1
CDCl3) : δ –62.13 (s, 3F, CF3); MS (FAB) 10 kV,
m/z (rel. int.) : 361 (M+) (100), 363 (M+2) (55),
360 [M–H]+ (48), 297 [M–SO2]+ (35), 270 [M–SO2–
HCN]+ (55) etc; Anal. Calcd for C15H11NO2ClF3S : C,
49.79; H, 3.04; N, 3.87. Found : C, 49.90; H, 3.10;
N, 3.93.
1
1160 (–CF3), 1130 (C-O-C); H NMR spectral data
(300.40 MHz, Me2SO-d6, δ ppm from TMS) : δ 8.06–
3
7.18 (m, 5H, Ar-H), 2.72 (q, 2H, JHH = 7.4 Hz,
3
CH2of C2H5 at C7), 1.17 (t, 3H, JHH = 6.8 Hz, CH3
of C2H5 at C7) ; 13C NMR (75.45 MHz, CDCl3, δ ppm
from TMS) : δ 138.40 (C-1), 119.2 (C-2), 122.5 (C-3),
130.7 (C-4), 128.0 (C-6), 128.2 (C-7), 126.9 (C-8),
118.0 (C-9), 120.7 (C-4a), 118.6 (C-5a), 139.9 (C-9a),
148.0 (C-10a), 31.4 (CH2of C2H5 at C7), 15.0 (CH3
of C2H5 at C7), 81.4 (C-1ꢁ), 75.5 (C-2ꢁ), 72.2 (C-3ꢁ),
70.3 (C-4ꢁ),123.1 (CF3 at C1,q, 1JCF = 270.90 Hz);19F
NMR (282.65 MHz, CDCl3) : δ –62.21 (s, 3F, CF3);
MS (FAB) 10 kV, m/z (rel. int.) : 785 (M+) (100), 756
[M–CH2CH3]+ (60), 620 [M–C5H2NO2F3]+ (100) etc;
Anal. Calcd for C41H31N2O9F3S : C, 62.75; H, 3.94; N,
3.56. Found : C, 62.93; H, 3.99; N, 3.65.
2.6 Synthesis of substituted
N-(2ꢁ,3ꢁ,5ꢁ-tri-O-benzoyl-β-D-ribofuranosyl)
phenothiazines (7a–d)
In 20 mL C6H5CH3, β-D-ribofuranose-1-acetate-2, 3,
5-tribenzoate (0.002 mol) was added to the solution
of substituted 10H-phenothiazines (5a–d) (0.002 mol)
and the contents were refluxed in vacuum with stir-
ring on an oil bath at 155–160◦C for 15 min. Fur-
ther, removing vacuum the reaction was protected from
moisture by fitting a guard tube. Stirring was further
continued for 10 h and after every 1 h; a vacuum was
applied for 10 min. In CH3OH, obtained viscous mass
was dissolved and boiled for 10 min. and cooled to
room temperature. The reaction mixture was filtered
and by distillation the CH3OH was removed, under
reduced pressure. In Et2O, obtained viscous residue
was dissolved. The mixture was filtered, concentrated
and kept in refrigerator overnight to get crystalline
ribofuranosides.
2.6c N-(2ꢁ,3ꢁ,5ꢁ-tri-O-benzoyl-β-D-ribofuranosyl)-7-
ethyl-3-fluoro-10H-phenothiazine (7c): Dark red
solid; m.p. : 120◦C–125◦C, Yield : 34% ; IR (KBr)
1
: v 1270 (C-F str. ),1125 (C-O-C); H NMR spectral
data (300.40 MHz, Me2SO-d6, δ ppm from TMS) : δ
8.02–6.74 (m, 5H, Ar-H), 2.54 (q, 2H, 3JHH = 7.3 Hz,
3
CH2of C2H5 at C7), 1.32 (t, 3H, JHH = 6.7 Hz, CH3
of C2H5 at C7) ; 13C NMR (75.45 MHz, CDCl3, δ ppm
from TMS) : δ 122.00 (C-1), 114.8 (C-2), 153.0 (C-3,
2.6a N-(2ꢁ,3ꢁ,5ꢁ-tri-O-benzoyl-β-D-ribofuranosyl)-
7-ethyl-3-trifluoromethyl-1-nitro-10H-phenothiazine
(7a): Brown solid; m.p. : 80◦C–85◦C, Yield : 70%
; IR (KBr) : v 1500 and 1360 (-NO2 str.), 1380 and
1190 (–CF3), 1150 (C-O-C); H NMR spectral data
(300.40 MHz, Me2SO-d6, δ ppm from TMS) : δ 8.21–
1
d, JCF = 249.4 Hz), 118.1 (C-4), 128.7 (C-6), 127.0
(C-7), 127.6 (C-8), 120.3 (C-9), 120.9 (C-4a), 119.2
(C-5a), 139.5 (C-9a), 138.9 (C-10a), 31.3 (CH2 of
C2H5 at C7), 14.2 (CH3 of C2H5 at C7) 81.0 (C-1ꢁ), 75.1
(C-2ꢁ), 71.7 (C-3ꢁ), 70.9 (C-4ꢁ);19F NMR (282.65 MHz,
CDCl3) : δ –110.00 (s, 1F, C–F); MS (FAB) 10 kV,
m/z (rel. int.) : 690 (M+) (100), 689 [M –H]+ (55), 660
[M–CH2CH3]+ (65), 620 [M–C4H3F]+ (60) etc; Anal.
Calcd for C40H32NO7SF : C, 69.60; H, 4.64; N, 2.03.
Found : C, 69.64; H, 4.69; N, 2.08.
1
3
6.94 (m, 5H, Ar-H), 2.79 (q, 2H, JHH = 7.5 Hz,
3
CH2of C2H5 at C7), 1.36 (t, 3H, JHH = 7.0 Hz, CH3
of C2H5 at C7); 13C NMR (75.45 MHz, CDCl3, δ ppm
from TMS) : δ 139.00 (C-1), 118.4 (C-2),122.0 (C-3),
131.5 (C-4), 129.0 (C-6), 128.9 (C-7), 128.4 (C-8),
119.0 (C-9), 120.5 (C-4a), 119.0 (C-5a), 139.3 (C-9a),
143.8 (C-10a), 32.1 (CH2of C2H5 at C7), 14.7 (CH3 of
C2H5 at C7), 80.2 (C-1ꢁ), 74.1 (C-2ꢁ), 70.6 (C-3ꢁ), 69.5 2.6d N-(2ꢁ,3ꢁ,5ꢁ-tri-O-benzoyl-β-D-ribofuranosyl)-
(C-4ꢁ), 121.7 (CF3 at C3, q, JCF = 271.10 Hz); 19F 2-chloro-7-ethyl-3-trifluoromethyl-10H-phenothiazine
1
NMR (282.65 MHz, CDCl3) : δ –62.37 (s, 3F, CF3); (7d): Dark brown solid; m.p. : 136◦C–140◦C, Yield :
MS (FAB) 10 kV, m/z (rel. int.) : 785 (M+) (100), 768 45% ; IR (KBr) : v 1344 and 1165 (–CF3) and 805 cm−1

Synthesis, biological activity of fluorinated 7-ethyl-10H-phenothiazines
201
1
inoculums was observed with spectrophotometer at
555 nm. The end result of the test was the mini-
mum inhibition concentration of antimicrobial (test
solutions), which gave clear solution, i.e., no visual
growth.
(C–Cl); H NMR spectral data (300.40 MHz, Me2SO-
d6, δ ppm from TMS) : δ 8.42–6.98 (m, 5H, Ar-H),
3
2.55 (q, 2H, JHH = 7.5 Hz, CH2of C2H5 at C7), 1.28
(t, 3H, 3JHH = 7.1 Hz, CH3 of C2H5 at C7) ; 13C NMR
(75.45 MHz, CDCl3, δ ppm from TMS) : δ 119.70 (C-
1), 129.8 (C-2), 119.2 (C-3), 127.7 (C-4), 130.9 (C-6),
128.4 (C-7), 127.0 (C-8), 120.1 (C-9), 118.9 (C-4a),
118.2 (C-5a), 139.6 (C-9a), 147.5 (C-10a), 32.0 (CH2of
C2H5 at C7), 15.0 (CH3 of C2H5 at C7), 115.9 (CF3
3.1b Anthelmintic activity: The synthesized com-
pounds were screened for anthelmintic activity against
Eudrilus species of earthworms by Garg and Atal
method18 at 4 mg/mL concentrations. Five earthworms
of nearly equal size were placed in standard drug solu-
tion and test compound solutions at room tempera-
ture. Suspensions of samples were prepared by tritu-
rating synthesized compounds (200 mg) with Tween
80 (0.5%) and distilled water and the resulting mix-
tures were stirred using a mechanical stirrer for 30 min
and diluted to contain 0.4% w/v of test samples. Sus-
pensions of reference drug Mebendazole was prepared
with same concentrations in similar way. Another set
of five earthworms was kept as control in suspen-
sion of distilled water and Tween 80 (0.5%). The par-
alyzing and death times were noted and their mean
was calculated and compared with standard drug.
The time taken by worms to become motionless was
noted as paralysis time. The death time was ascer-
tained by placing earthworms in warm water (50◦C),
which stimulate the movement, if the worm was
alive.
1
at C3,q, JCF = 275.00 Hz);19F NMR (282.65 MHz,
CDCl3) : δ –62.32 (s, 3F, CF3); MS (FAB) 10 kV,
m/z (rel. int.) : 774 (M+) (100), 776 (M+2) (52), 773
[M –H]+ (40), 745 [M–CH2CH3]+ (65), 620 [M–
C5H2F3Cl]+ (60) etc; Anal. Calcd for C41H31NO7SF3Cl
: C, 63.60; H, 4.00; N, 1.80. Found : C, 63.64 ; H, 3.95 ;
N, 1.83.
3. Biological activity
3.1 In vitro antibacterial and antifungal assay
3.1a Minimum inhibitory concentrations: The syn-
thesized compounds were tested for their antimicro-
bial activity in the form of MIC’s. Minimum inhi-
bition concentration (MIC) is the lowest concentra-
tion of test compound which have been screened
for their antimicrobial (antibacterial and antifungal)
activity.16,17 At this lowest concentration of test com-
pounds, appears the inhibition of visible growth of
bacteria and fungi after 22–24 h, incubation at 37◦C.
The determination of the MIC involves a semi quan-
titative test procedure, which gives an approxima-
tion to the least concentration of an antimicrobial
4. Results and discussion
(test solution) needed to parent microbial growth. The 7-Ethyl-3-trifluoromethyl-1-nitro-10H-phenothiazine
MIC was determined by the liquid dilution method. (5a) was prepared by refluxing 2-amino-5-ethyl-
Two Gram-positive (Staphylococcus aureus and Bacil- benzenethiol (1a) with 4-chloro-3, 5-dinitroben-
lus subtilis) and two Gram-negative (Escherichia coli zotrifluoride (2a) in the presence of sodium hydrox-
and Pseudomonas aeruginosa) were used as qual- ide in alcohol via Smiles rearrangement in situ.
ity control strains. For the antifungal activities of 10H-phenothiazines (5b–d) were synthesized by sub-
the compounds Candida albicans and Aspergilius stituted 2-formamido-2ꢁ-nitrodiphenylsulphides (4b–d)
niger were tested. Ciprofloxacin and Griseofulvin via Smiles rearrangement. The formyl derivatives
were used as standard antibacterial and antifungal were synthesized by the formylation of 2-amino-2ꢁ-
agents, respectively. The stock solutions of test com- nitrodiphenylsulphides (3b–d), which in turn were pre-
pounds with 1 to 20 μg/mL concentrations were pre- pared by condensation of 2-amino-5-ethylbenzenethiol
pared with aqueous methanol (1:1). Inoculums of (1a) with o-halonitrobenzenes (2b–d) in ethanolic so-
the overnight culture were prepared. In a series of dium acetate solution. Their corresponding sulphones
tubes, 1 mL each of stock solutions of test com- (6a–d) were synthesized by refluxing 10H-pheno-
pound with different concentrations was taken and thiazines (5a–d) with 30 % H2O2 in glacial acetic
0.4 mL of the inoculums was added to each tube. acid. The spectral changes have been observed when
Further 4.0 mL of sterile water was added to each sulphides convert to sulphones (IR and NMR data
of the test tubes. These test tubes were incubated for in sec. 2.1, 2.4 and 2.5). The oxidation of 10H-
22–24 h at 37◦C and observed for the presence of phenothiazine to their corresponding sulphones causes
turbidity. The absorbance of the suspension of the appearance of specific absorption peak with the change

202
Naveen Gautam et al.
in the vibrational modes. These changes in the vibra- 4.1 Antimicrobial activity
tional modes could be elaborated by the strong electron
A series of novel heterocyclic compounds 5a–d, 6a–d
withdrawing oxygen atoms at the oxidized sulphide
linkage. Ribofuranosides (7a–d) were synthesized by
treatment of 10H-phenothiazines (5a–d) with β-D-
ribofuranosyl-1-acetate-2, 3, 5-tribenzoate in toluene
under vacuum (scheme 1).
The structures proposed for the synthesized com-
pounds were well-determined by elemental analy-
sis and spectral data. The synthesized compounds
were also screened for antimicrobial and anthelmintic
activities.
and 7a–b were synthesized. The minimum inhibitory
concentration (MIC) of the compounds varies from
9.50–19.30 μg/mL. Seven compounds of the obtained
series i.e., 5a, 5b, 6a, 6b, 6d and 7a showed good acti-
vity and remaining showed moderate activity against
bacteria E. coli. Compounds 6a, 6b and 6d showed
good and remaining showed moderate activity against
bacteria B. subtilis. For bacteria P. aeruginosa com-
pounds 5a, 6a, 6b, 6c, 7a and 7d showed good activity
NH2
SH
NO2
+
R3
R2
NH2 NO2
R3
R2
CH3COONa
C2H5OH
C2H5
X
C2H5
S
R1
x = F (2c)
R1
3b-d
2b-d
1a
x= Cl ( 2b & 2d )
C2H5OH/NaOH
x=Cl (2a)
Formylation
90% HCOOH
R1 =NO2
H
N
R1
1
CHO
9
10
5
2
8
R2
Acetone
NH NO2
R3
R2
3
R3
KOH/EtOH
C2H5
S
4
7
C2H5
S
6
5a-d
R1
4b-d
BzO
O
CO
CH3
O
BzO
O
B
z
30% H2O2/
gl.AcOH
Bz =Benzoyl group
Toluene under vaccum
155-160oC
7a-d
BzO OBz
3´
4´
BzO
2´
1´
H
N
R1
1
9
8
10
R2
O
2
R1
1
9
10
C2H5
3
R3
S
7
5
O
N
R2
R3
6
8
7
4
O
2
3
C2H5
S
5
6
4
6a-d
Compounds
5a, 6a, 7a
5b, 6b, 7b
R1
R2
H
H
H
Cl
R3
CF3
NO2
F
NO2
CF3
H
7c
5c, 6c,
5d, 6d,
H
CF3
7d
Scheme 1. Synthesis of Phenothiazine, their sulfones and nucleosides.

Synthesis, biological activity of fluorinated 7-ethyl-10H-phenothiazines
203
Table 1. Minimum inhibitory concentrations (μg/mL) of synthesized compounds.
Minimal inhibition concentrations of bacterial strains (MIC) in μg/mL
Compd. No.
E. coli
B. subtilis
P. aeruginosa
S. aureus
5a
5b
5c
5d
6a
6b
6c
6d
7a
7b
7c
7d
10.10 0.29 11.60 0.10 09.90 0.05
10.30 0.11 11.50 0.22 13.90 0.10
16.00 0.35 19.30 0.30 11.10 0.10
11.70 0.15 12.20 0.19 11.30 0.17
09.50 0.20 10.70 0.25 09.70 0.23
10.00 0.09 10.80 0.26 10.70 0.35
15.30 0.21 19.00 0.10 09.80 0.10
10.40 0.10 10.60 0.35 11.20 0.22
09.60 0.16 11.90 0.10 10.50 0.19
13.30 0.20 15.10 0.19 13.90 0.24
15.90 0.10 19.20 0.30 12.00 0.15
11.40 0.20 15.30 0.15 10.90 0.20
11.00 0.30
12.50 0.11
15.00 0.16
16.30 0.21
10.00 0.17
10.90 0.30
14.30 0.05
13.80 0.15
12.10 0.19
11.80 0.17
14.60 0.20
16.10 0.10
04.90 0.11
Ciprofloxacin 04.10 0.10 04.90 0.13 03.85 0.15
Table 2. MIC (μg/mL) of synthesized compounds.
Minimal inhibition concentrations of fungal strains (MIC) in μg/mL
Compd. No.
C. albicans
A. niger
5a
5b
5c
5d
6a
6b
6c
6d
7a
7b
7c
7d
10.10 0.13
11.10 0.17
13.10 0.18
11.00 0.10
09.50 0.20
10.50 0.20
12.70 0.11
10.30 0.29
09.90 0.35
13.30 0.22
15.80 0.17
10.50 0.30
03.10 0.08
09.80 0.22
16.40 0.31
16.80 0.08
12.70 0.18
09.70 0.22
15.00 0.10
16.00 0.35
12.30. 0.26
11.00. 0.17
16.00 0.26
13.70 0.15
12.40 0.20
04.80 0.10
Griseofulvin
Table 3. Anthelmintic activity of synthesized compounds.
Time in min
Paralyzing time
100 mg/mL
Death time
100 mg/mL
Compd. No.
200 mg/mL
50 mg/mL
200 mg/mL
50 mg/mL
5a
5b
5c
5d
6a
6b
6c
6d
7a
7b
7c
7d
13.00 1.00
11.00 1.00
13.16 1.25
12.00 1.00
15.00 0.77
13.26 1.08
15.16 1.24
12.85 1.22
12.20 1.00
14.00 1.10
13.95 1.25
11.60 1.20
12.50 1.04
18.00 1.00
15.00 1.00
17.00 1.00
16.00 1.10
18.69 0.79
18.55 1.05
18.00 0.78
15.00 1.09
16.50 1.20
17.33 1.52
18.10 1.00
16.40 1.10
16.00 0.98
25.00 0.33
22.50 0.50
25.00 0.70
21.00 1.00
23.36 1.00
23.45 0.93
22.78 0.60
20.03 0.68
21.00 1.00
25.50 1.32
23.60 0.70
20.20 1.05
21.80 1.34
20.00 1.00
21.16 1.04
18.16 0.76
19.50 0.50
20.16 1.22
15.40 0.77
21.11 0.77
13.15 0.67
19.10 0.55
20.50 0.50
18.00 0.76
16.50 0.50
15.26 0.84
32.66 1.52
27.16 0.76
25.16 0.76
28.16 0.76
24.13 1.09
22.20 1.00
25.88 1.00
16.16 0.84
26.06 0.76
26.66 2.08
24.90 1.00
24.10 0.50
22.65 0.90
40.21 0.25
35.23 0.91
37.53 0.55
35.50 0.50
34.12 0.60
29.25 1.00
32.22 0.63
20.00 0.70
34.50 0.50
38.50 0.50
35.35 0.55
30.95 0.50
30.55 1.00
Mebendazole

204
Naveen Gautam et al.
and remaining showed moderate activity. Compounds Acknowledgements
5a, 6a and 6b showed good activity and remaining
The authors thank the Department of Chemistry, Uni-
showed moderate activity against bacteria S. aureus.
Compounds 5a, 5d, 6a, 6d, 7a and 7d showed good
activity against fungi C. albicans and remaining showed
moderate activity. For fungi A. niger compounds 5a,
6a and 7a showed good activity and remaining showed
moderate activity. These results are presented in tables 1
and 2.
versity of Rajasthan, and Jaipur for providing necessary
facilities. The University Grants Commission (UGC)
Research Award Scheme, New Delhi is duly acknowl-
edged for financial support through them. Authors are
also thankful to Rajiv Academy for Pharmacy, Mathura
for assistance in carrying out the biological activities.
References
4.2 Anthelmintic activity
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5. Conclusion
All the synthesized 10H-phenothiazines, their sul-
phones and ribofuranosides showed good antifungal
and antibacterial activities. In antimicrobial activity,
the MIC values of antibacterial and antifungal screen-
ing predict that compounds 6a and 6b exhibited
good antibacterial activities against all the four
strains of bacteria. In fact, compounds 6a–d exhi-
bited significant antibacterial and antifungal activities
as compared to their phenothiazines 5a–d, respectively
due to electron withdrawing effect of oxygen in 6a–d.
In anthelmintic activity, compounds 5b, 5d, 6d 7a
and 7d showed significant paralytic time and com-
pounds 6b and 6d showed better death time of earth-
worms with that of standard drug Mebendazole.
18. Dahiya R and Pathak D 2007 Eur. J. Med. Chem. 42 772