3.1. Synthesis: 1-(substituted benzylideneamino)-3-methyl-1,3,4,5-tetrahydro-2H-benzo[d]azepin-2-one (T1-T15) derivatives
2-Phenylethyl bromide undergoes amino alkylation through mannich reaction with CH3NH2 and chloro acetyl chloride, gives 2-chloro-N-methyl-N-phenethylacetamide, which is further undergoing cyclization gives 3-methyl-1,3,4,5-tetrahydro-2H-benzo[d]azepin-2-one (Fig. 1). 3-methyl-1,3,4,5-tetrahydro-2H-benzo[d]azepin-2-one on reaction with isoamylnitrite yields 1-(hydroxyimino)-3-methyl-1,3,4,5-tetrahydro-2H-benzo[d]azepin-2-one which is on reduction in the presence of IPA, yields 1-amino-3-methyl-1,3,4,5-tetrahydro-2H-benzo[d]azepin-2-one. Hydroxyl imine group reduced to amine. 1-amino-3-methyl-1,3,4,5-tetrahydro-2H-benzo[d]azepin-2-one. di-p-toluoyl-1-tartaric acid and 1-amino-3-methyl-1,3,4,5-tetrahydro-2H-benzo[d]azepin-2-one. HCl was obtained by treatment with di-p-toluoyl-l-tartaric acid and con. HCl respectively. 1-amino-3-methyl-1,3,4,5-tetrahydro-2H-benzo[d]azepin-2-one. HCl undergoes nucleophilic addition reactions with different substituted benzaldehydes and yields final derivatives (1-(substituted benzylideneamino)-3-methyl-1,3,4,5-tetrahydro-2H-benzo[d]azepin-2-one) (T1-T15) after 6–12 hr reflux in DMSO solvent. Derivatives yielded 60–70% and were recrystallized with ethanol (Fig. 2).
Table 6
R Group Substitutions of compounds synthesized (T1-T15)
S. No
|
Compound
|
Substitution (R)
|
1
|
T1
|
H
|
2
|
T2
|
3-NO2
|
3
|
T3
|
3-Chloro
|
4
|
T4
|
4-methyl
|
5
|
T5
|
4-Bromo
|
6
|
T6
|
3,4,5-tri hydroxy
|
7
|
T7
|
2-hydroxy
|
8
|
T8
|
4-chloro
|
9
|
T9
|
3,4,5-tri methoxy
|
10
|
T10
|
2,4,6-tri chloro
|
11
|
T11
|
3-hydroxy
|
12
|
T12
|
4-iso propyl
|
13
|
T13
|
4-di methyl amine
|
14
|
T14
|
4-methoxy
|
15
|
T15
|
2, 4-di chloro
|
Spectral Interpretation of Synthesized Compounds
2-chloro-N-methyl-N-phenethylacetamide (Inter-2)
67.5%; 1H NMR: δ 2.58 (3H, s), 2.83 (2H, t), 3.35 (2H, t), 4.13 (2H, s), 7.04–7.35 (5H, 7.11 (dddd), 7.20 (tt), 7.28 (tdd)).; MASS: 212.0 M++1
3-methyl-1,3,4,5-tetrahydro-2H-benzo[d]azepin-2-one (Inter-3)
64.85% yield; 1H NMR: δ 2.87 (2H, ddd), 3.04 (3H, s), 3.55–3.71 (4H, 3.63 (ddd), 3.63 (d)), 7.03 (1H, ddd), 7.10–7.29 (3H, 7.17 (ddd), 7.18 (ddd), 7.23 (ddd)).; MASS: 176.0M++1
1-(hydroxyimino)-3-methyl-1,3,4,5-tetrahydro-2H-benzo[d]azepin-2-one (Inter-4)
62% yield; 1H NMR: δ 2.81 (2H, ddd), 3.06 (3H, s), 3.60 (2H, ddd), 7.17 (1H, ddd), 7.25–7.40 (2H, 7.32 (ddd), 7.33 (ddd)), 7.87 (1H, ddd).
1-amino-3-methyl-1,3,4,5-tetrahydro-2H-benzo[d]azepin-2-one (Inter-5, 6, & 7)
67% yield; 79% yield; 41% yield; 1H NMR: δ 2.80–2.96 (2H, 2.88 (ddd), 2.87 (ddd)), 3.07 (3H, s), 3.49–3.71 (2H, 3.56 (ddd, 3.63 (ddd)), 4.99 (1H, s), 7.04–7.18 (3H, 7.10 (td), 7.10 (ddd), 7.12 (td)), 7.26 (1H, ddd).
1-(benzylideneamino)-3-methyl-1,3,4,5-tetrahydro-2H-benzo[d]azepin-2-one (T1)
65% yield; 1H NMR: δ 2.83–3.02 (2H, 2.90 (ddd), 2.95 (ddd)), 3.08 (3H, s), 3.48–3.72 (2H, 3.56 (ddd), 3.63 (ddd)), 5.24 (1H, s), 7.08–7.34 (4H, 7.15 (ddd), 7.14 (ddd), 7.24 (ddd), 7.28 (ddd)), 7.37–7.52 (3H, 7.43 (tt), 7.45 (dddd)), 8.19 (2H, dddd), 8.42 (1H, s); MASS: 272.7 M++3.
Table 7
Physical Properties of synthesized compounds (T1-T15)
S. No
|
Compounds
|
Mol.
Formula
|
Mol.
weight
|
Melting point ( ˚C)
|
**Rf
values
|
1
|
T1
|
C18H18N2O
|
278.36
|
192–195
|
0.78
|
2
|
T2
|
C18H17N3O3
|
323.35
|
191–194
|
0.12
|
3
|
T3
|
C18H17ClN2O
|
312.80
|
98–100
|
0.52
|
4
|
T4
|
C19H20N2O
|
292.38
|
182–183
|
0.12
|
5
|
T5
|
C18H17BrN2O
|
357.25
|
175–178
|
0.86
|
6
|
T6
|
C18H18N2O4
|
326.35
|
105–107
|
0.53
|
7
|
T7
|
C18H18N2O2
|
294.35
|
102–105
|
0.57
|
8
|
T8
|
C18H17ClN2O
|
312.80
|
110 − 104
|
0.62
|
9
|
T9
|
C21H24N2O4
|
368.43
|
120–123
|
0.49
|
10
|
T10
|
C18H15Cl3N2O
|
381.68
|
99–102
|
0.55
|
11
|
T11
|
C18H18N2O2
|
294.35
|
98–101
|
0.62
|
12
|
T12
|
C21H24N2O
|
320.44
|
103–106
|
0.36
|
13
|
T13
|
C20H23N3O
|
321.42
|
110–113
|
0.10
|
14
|
T14
|
C19H20N2O2
|
308.38
|
108–111
|
0.58
|
15
|
T15
|
C18H16Cl2N2O
|
347.24
|
96–99
|
0.92
|
3.2. In Vitro Cytotoxicity Assay
The MTT assay was performed to screen the synthesized compounds on Vero and MDA MB 231 cells, and the results are shown in Table 8, Fig. 3. Even at higher concentrations of synthesized derivatives for treatment, no cytotoxicity was observed in normal cells. Title compounds have exhibited low to high in-vitro anticancer activity with MDA MB 231 cells. Four of the synthesized compounds have shown good IC50 values like T2 (35 µg/ml), T10 (36.606 µg/ml), T14 (11 µg/ml), T15 (22 µg/ml).
Chemical Structures of synthesized compounds (T1-T15)
Table 8
Cytotoxicity results of synthesized benzoazepinone derivatives
S. No
|
Compound
|
VERO (µg/ml)
|
MDA MB 231 (µg/ml)
|
1
|
T1
|
314.9
|
150
|
2
|
T2
|
58
|
35
|
3
|
T3
|
596
|
124
|
4
|
T4
|
304
|
153
|
5
|
T5
|
106
|
58
|
6
|
T6
|
96
|
91
|
7
|
T7
|
85
|
68
|
8
|
T8
|
94
|
63
|
9
|
T9
|
99
|
112
|
10
|
T10
|
76
|
36
|
11
|
T11
|
148
|
69
|
12
|
T12
|
104
|
61
|
13
|
T13
|
126
|
102
|
14
|
T14
|
31
|
11
|
15
|
T15
|
33
|
22
|
Standard
|
Raloxifene
|
15
|
6
|