6
VENKATESAN ET AL.
The progress of reaction was checked by TLC. After reac-
tion was completed, the reaction mass was cooled to room
temperature and then discharged into cold water (200 mL)
and neutralized with ammonium hydroxide. The obtained
solid was filtered, washed with water and crystallized from
alcohol.
3-(4,5-diphenyl-1H-imidazol-2-yl)-10-methyl-10H-
phenothiazine (5a) mp. 252-255ꢀC; IR (KBr) νmax: 3421,
3057, 2962, 1602, 1462, 1450, 1334, 1257, 1139,
1072 cm−1; 1H NMR (400 MHz, DMSO-d6, ppm),
δH = 12.56 (s, 1H, NH); 7.92 (d, 1H, J = 8.0 Hz, Ar H of
phenyl ring); 7.87 (s, 1H, Ar H of phenyl ring); 6.98-7.55
(m, 15H, Ar H of phenothiazine and phenyl ring); 3.35
(s, 3H, CH3); 13C NMR (100.612 MHz, DMSO-d6, ppm),
δC = 145.14, 144.88, 144.78, 136.97, 135.18, 131.05,
128.62, 128.27, 123.28, 122.69, 122.30, 121.55, 114.77,
114.72, 35.26; HRMS (EI): m/z [M+] calcd. For
C28H21N3S: 431.1456; found: 431.1456.
3-(4,5-diphenyl-1H-imidazol-2-yl)-10-ethyl-10H-pheno-
thiazine (5b) mp. 235-238ꢀC; IR (KBr) νmax: 3421, 3132,
2987, 2935, 1604, 1462, 1382, 1328, 1251, 1136, 1072 cm−1;
1H NMR (400 MHz, DMSO-d6, ppm), δH = 12.61 (s, 1H,
NH); 7.89 (d, 1H, J = 8.4 Hz, Ar H of phenyl ring); 7.84
(s, 1H, o- Ar H of phenyl ring); 6.93-7.52 (m, 15H, Ar H
of phenothiazine and phenyl ring); 3.95 (d, 2H,
J = 6.0 Hz, CH2); 1.32 (t, 3H, J = 5.4 Hz, CH3); 13C NMR
(100.612 MHz, DMSO-d6, ppm), δC = 144.76, 144.25,
143.83, 128.38, 127.73, 127.68, 127.08, 124.72, 124.60,
123.49, 123.00, 122.58, 122.29, 115.54, 115.41, 41.20, 12.61;
HRMS (EI): m/z [M+] calcd. For C29H23N3S: 445.1613;
found: 445.1613.
121.56, 121.19, 115.68, 115.44, 114.81, 35.95; HRMS (EI):
m/z [M+] calcd. For C20H15N3S: 329.0987; found:
329.0987.
3-(1H-benzo[d]imidazol-2-yl)-10-ethyl-10H-pheno-
thiazine (6b) mp. 162-165ꢀC; IR (KBr) νmax: 3441, 2980,
2929, 2854, 1629, 1602, 1581, 1460, 1373, 1330, 1253,
1
1180, 1138 cm−1; H NMR (500 MHz, DMSO-d6, ppm),
δH = 8.10 (dd, 2H, J = 2.0 & 8.5 Hz, p- Ar H of phenyl
ring); 7.93 (d, 1H, J = 2.0 Hz, NH); 7.67-7.70 (m, 2H, C-2,
C-6 Ar H of ptz ring); 7.36 (q, 2H, J = 4.5 Hz, Ar H of
phenyl ring); 6.97-7.48 (m, 5H, Ar H of phenothiazine
ring); 4.01 (q, 4H, J = 6.5 Hz, CH2); 1.31 (t, 3H,
J = 6.75 Hz, CH3); 13C NMR (125.757 MHz, DMSO-d6,
ppm), δC = 149.86, 147.47, 143.47, 135.95, 128.48, 127.63,
127.49, 125.75, 124.32, 123.72, 123.69, 122.13, 120.68,
116.36, 116.06, 114.75, 41.96, 12.97; HRMS (EI): m/z
[M+] calcd. For C21H17N3S: 343.1143; found: 343.1142.
Procedure for the preparation of 2-(9H-carbazol-9-yl)-
N0-((10-methyl-10H-phenothiazin-3-yl)methylene)acet-
ohydrazide 7(a-b).
In a 50 mL round bottomed flask a mixture of 10-alkyl-
10H-phenothiazine-3-carbaldehyde 3(a-b) (1 mmol), 2-(9H-
carbazol-9-yl)acetohydrazide (1 mmol), 1 mL of glacial
acetic acid and methanol 25 mL were taken. The resulting
solution was refluxed for 3-4 hour. The progress of the reac-
tion was supervised by thin layer chromatography. After
reaction was completed, the reaction mass could cool at
room temperature and the solid separated was filtered off
and washed with large amount of methanol (40 mL) and
dried at room temperature.
2-(9H-carbazol-9- yl)-N0- ([10-methyl-10H-phenothiazin-
3-yl] methylene) acetohydrazide (7a) mp 172-175ꢀC; IR
(KBr) νmax: 3224, 3072, 2872, 1674, 1598, 1575, 1463, 1382,
1257, 1151 cm−1; 1H NMR (500 MHz, DMSO-d6, ppm),
δH = 11.63 (s, 1H, NH), 8.19 (s, 1H, N CH), 8.16-8.17 (split
peaks, 1H, C5-Ar H of carbazole ring), 7.99 (s, 1H,
C4-Ar H of carbazole ring), 7.65 (d, 1H, J = 2.0 Hz,
C1-Ar H of carbazole ring), 6.98-7.59 (m, 12H, Ar H of
carbazole and phenothiazine ring), 5.17 (s, 2H, NCH2), 3.36
(s, 3H, CH3); 13C NMR (125.757 MHz, DMSO-d6, ppm),
δC = 164.38, 147.27, 147.68, 146.91, 145.66, 144.99, 143.44,
141.34, 141.16, 129.01, 128.94, 128.40, 127.94, 127.60, 127.33,
126.18, 126.07, 125.39, 124.97, 123.37, 122.73, 121.98, 121.91,
120.55, 119.55, 119.34, 115.41115.17, 115.03, 109.88, 109.82,
44.15, 35.84; HRMS (EI): m/z [M+] calcd. For C28H22N4OS:
462.1514 found: 462.1513.
Procedure for the preparation of 3-(1H-benzo[d]
imidazol-2-yl)-10-alkyl-10H-phenothiazine 6(a-b).
In a 50 mL round bottom flask, a mixture of o-
phenylenediamine (1 mmol) and 10-alkyl-10H-phenothia-
zine-3-carbaldehyde (1 mmol) in DMF (10 mL) were mixed
and stirred in the presence of sodium metabisulfite
(Na2S2O5) catalyst (10 mol%) at 80ꢀC for 7 hours. The pro-
gress of reaction mixture was monitored by TLC. After reac-
tion was completed, the reaction mass was cooled and then
discharged into ice cooled water and the solid obtained was
filtered, washed with excess of H2O and dried. Column
chromatography was used to purify the crude product.
3-(1H-benzo[d]imidazol-2-yl)-10-methyl-10H-pheno-
thiazine (6a) mp. 173-175ꢀC; IR (KBr) νmax: 3419, 1629,
1
1581, 1460, 1340, 1259, 1087 cm−1; H NMR (500 MHz,
DMSO-d6, ppm), δH = 8.04 (dd, 1H, J = 2.0 & 8.5 Hz, p-
Ar H of phenyl ring); 7.96 (d, 1H, J = 2.0 Hz, NH);
7.01-7.36 (m, 8H, Ar H of phenothiazine and phenyl
ring); 7.68 (q, 2H, J = 3.25 Hz, C-2, C-6 Ar H of pheno-
thiazine ring); 3.32 (s, 3H, CH3); 13C NMR (125.757 MHz,
DMSO-d6, ppm), δC = 150.00, 148.31, 144.64, 136.25,
128.59, 127.55, 127.42, 125.52, 124.18, 123.74, 123.23,
2-(9H-carbazol-9-yl)-N0-([10-ethyl-10H-phenothiazin-
3-yl]methylene)acetohydrazide(7b).
mp 185-188ꢀC; IR (KBr) νmax: 3219, 3062, 2964, 2914,
1681, 1597, 1546, 1485, 1460, 1325, 1244, 1211, 1155,
1080 cm−1
;
1H NMR (500 MHz, DMSO-d6, ppm),
δH = 11.62 (s, 1H, NH), 8.16, (d, 2H, J = 7.5 Hz, N=CH &
C5-Ar H of carbazole ring), 7.97 (s, 1H, C4-Ar H of