INTRODUCTION:

1, 5-Benzodiazepines:

1, 5-Benzodiazepines are bi cyclic compounds with two nitrogen atoms at 1 and 5 positions in a seven membered ring fused to a benzene ring. Benzo di azepines have attracted greater attention as an important class of heterocyclic compounds in the field of drugs and pharmaceuticals. This nucleus is a pharmacophoric scaffold and represent a class of heterocycles with a wide range of biological applications[1]. Many of them are widely used as anticonvulsant, antianxiety, sedative, anti depressive, hypnotic and neuroleptic agents[2-5]. Some heterocycles containing benzodiazepines moiety were reported to possess anti inflammatory[6], antiviral[7], anti-HIV-1[8], antimicrobial[9] and antitumor[10] activities.

Other than their biological importance, benzodiazepines are valuable synthons for the preparation of fused ring compounds, such as triazolo[11], thiazolo[12], imidazo[13] and pyrimido-benzodiazepines[14]. It has been noticed that introduction of an additional ring to the benzodiazepine core tends to exert profound influence in conferring novel biological activities in these molecules[11-15]. Although many methods for synthesizing benzodiazepine ring systems have been reported, they continue to receive a great deal attention[ 16-20 ]. The core structure of benzodiazepines. "R" labels denote common locations of side chains, which give different benzodiazepines their unique properties[21-22]. A benzodiazepine (sometimes colloquially "benzo"; often abbreviated "BZD") is a psychoactive drug whose core chemical structure is the fusion of a benzene ring and a di azepine ring. The first benzodiazepine, chlordiazepoxide (Librium), was discovered accidentally by Leo Sternbach in 1955, and made available in 1960 by Hoffmann– La Roche, which has also marketed diazepam (Valium) since 1963[23] . Benzodiazepines enhance the effect of the neurotransmitter gamma-amino butyric acid (GABA-A), resulting in sedative, hypnotic (sleep-inducing), anxiolytic (antianxiety), anticonvulsant, and muscle relaxant properties; also seen in the applied pharmacology of high doses of many shorter-acting benzodiazepines are amnesic-dissociative actions. These properties make benzodiazepines useful in treating anxiety, insomnia, agitation, seizures, muscle spasms, alcohol withdrawal and as a premedication for medical or dental procedures. 1, 5-Benzodiazepines are bicyclic compounds with two nitrogen atoms at 1 and 5 positions in a seven membered ring fused to a benzene ring [Fig 1]. Basically 1, 5- benzodiazepines are the 2, 3-benzo annelated derivatives of 1, 4-diazepines [24].

Benzodiazepines are numbered as shown in figure 2

Fig 2

Biological Importance of 1, 5-Benzodiazepines :

The ascendancy of the 1, 5-benzodiazepines in chemical literature is doubtless a consequence of their easy accessibility and the activity they show against a variety of targets including peptide hormones (such as CCK), interleukin converting enzymes (ICE), and potassium blockers (IK). The enormous amount of research work that has been conducted in the pharmaceutical laboratories on these compounds during last several decades derives its inspiration from the discovery of the remarkable tranquilizing, CNS depressants [25], anti-inflammatory [26], antispasmodic, antidepressive [27], antifungal, antibacterial, antifeedant, analgesic, anticonvulsant, muscle relaxant, hypnotic and sedative activity etc. observed with certain members of this heterocyclic system. of particular importance are the substituted and tricyclic derivatives which are not only used as anxiolytic or antineoplastic agents but their novel application is continuously emerging. The recent demonstration that some of their derivatives can serve as potential agents in the control and treatment of AIDS has stimulated further interest in these compounds from yet another perspective. Table- 1 gives the list of substituted and tricyclic 1, 5-benzodiazepines whose antineoplastic and anti-HIV activity has appeared in the literature.

In spite of their importance from a pharmaceutical, industrial, synthetic point of view comparatively few methods for their preparation are reported in the literature, a great number of which have appeared only very recently. These include condensation reactions of o-phenylene di amines with α, β unsaturated carbonyl compounds [28], β halo ketones [29] or ketones in the presence of BF₃-Etherate [30],NaBH₄ [31],Poly phosphoric acid [32], SiO₂[33], MgO and POCl₃ [34], Yb(OTf)₃ [35],

Al₂O₃/P₂O₅[36].

Table-1 Pharmacological Properties of Substituted and Tricyclic Derivatives of 1, 5-Benzodiazepines:

S.NO	Structure of the compounds	Name of the compounds	Pharmacological properties
1		Pirenzepine	Act selectively as Muscarinic receptor(M1) antagonist
2		Nevirapine	Act as Anti-HIV agent
3		Clobazam	Act as Antiepileptic agent

MATERIALS AND METHODS:

Melting points were determined in open-end capillaries and are uncorrected. Compounds were checked for their purity by TLC on silica gel G plates and spots were located by iodine vapors. ¹H NMR spectra were recorded on Bruker Advance II 400 NMR Spectrometer using TMS as internal standard. The mass spectra were obtained on a JEOL 5x102/DA-6000 mass spectrometer. The IR spectra were recorded on Perkin-Elmer spectrum RX IFT-IR System using KBr pellets. Elemental analyses of the newly synthesized compounds were carried out on Perkin Elmer model 2400 C H N analyzer. All the compounds gave satisfactory elemental analysis within ±0.4% of theoretical values.

Scheme I:

The synthetic route was depicted in scheme I The title compounds 13(a-g) were synthesized in nine sequential steps using different reagents and reaction conditions, the 13(a-g) were obtained in moderate yields. The structure were established by spectral (IR, ¹H-NMR, ¹³C-NMR and mass) and analytical data.

Synthetic Scheme I:

Reagents and Reaction conditions: (a)Methane Sulfonic acid, Sodium nitrate,0⁰C-RT (b) Pd(PPh₃)_4, Sodium carbonate in ethanol and toluene,(c)1,4 di oxane, TEA, Reflux (d)Fe Powder, Acetic acid (e) potassium peroxomonosulphate in methanol, water, (f) P₂S₅,Pyridine,100⁰C, CH₃CN, K₂CO₃, 80⁰C, (g)hydrazine hydrate, Ethanol, Reflux (h) Tri ethyl ortho acetate (i) Aceto nitrile,K₂CO₃,120⁰C,MW Irradiation, 1 hr

Synthetic Scheme II:

Nucleophile Structure	Final Compound Structure
12a

EXPERIMENTAL SECTION:

All reactions were carried out under argon in oven-dried glassware with magnetic stirring. Unless otherwise noted, all materials were obtained from commercial suppliers and were used without further purification. All solvents were reagent grade. THF was distilled from sodium benzophenone ketyl and degassed thoroughly with dry argon directly before use. Unless otherwise noted, organic extracts were dried with anhydrous Na₂SO₄,filtered through a fritted glass funnel, and concentrated with a rotary evaporator (20–30 Torr). Flash chromatography was performed with silica gel (60–120 mesh) by using the mobile phase indicated. The NMR spectra were measured with a 400 MHz Bruker Avance spectrometer at 400.1 and 100.6 MHz, for ¹H, for ¹³C, respectively, in CDCl₃ solution with tetra methyl silane as internal standard. Chemical shifts are given in ppm (δ) and are referenced to the residual proton resonances of the solvents.

Synthesis of 4-bromo-2-fluoro-1-nitrobenzene (3) [37] :

In a 50 ml RB-flask was charged with commercially available 1-bromo-3-fluoro-benzene (0.1 m. mol) and methane sulfonic acid (10 ml). The reaction was vigorously stirred and sodium nitrate ( 0.15 m. mol) was added in small portions to the reaction mixture while the temperature was maintained below 30⁰ C. After addition of sodium nitrate, the reaction was stirred at RT for 5 hours. The reaction mixture was poured into 150 ml ice-water and the aqueous layer was extracted with dichloromethane (2.x. 50 ml). The organic extracts were washed once with saturated NaHCO₃/H₂O (150 ml). The combined extracts were dried (Na₂SO₄), filtered, and evaporated to dryness in vacuum. The crude product was distilled (bp 85⁰ C., 2.3 torr) to afford as a light yellow oil, which solidified upon standing at room temperature in a yield of 81% . 4-bromo-2-fluoro-1-nitrobenzene could be obtained pure by re crystallization from a little warm methanol.

Melting Point: 185-186⁰C

¹H NMR (DMSO-d_6, δ ppm, 400 M.Hz) δ 7.7(1H,d,C_H-F), 7.9( 1H, d, J=8.3 HZ), 8.2 (1H,d, J=8.3 HZ) The EIMS m/z values and corresponding percentage were as follows: 220 (M⁺ 100%), 222 (M+2, 100%) Indicates compound contains one bromine atom present.

IR(KBr,cm-¹): 3110 cm^-1 (ArC-H stret), 1550 cm^-1 (C=C Stret), 1340 cm^-1 ( C-F Stretching), 550 cm^-1 (C-Br Stretch), 1515 and1345 cm^-1 ( doublet, N-O Stretching in nitro group), 1140 cm^-1 (C-N Stretching) Wave numbers respectively.

Synthesis of 2-fluoro-4-methyl-1-nitrobenzene (4) [38]:

To a solution of 4-bromo-2-fluoro-1-nitrobenzene (2) (2 m.mol) in toluene (15 ml) and ethanol (5 ml) was added 2,4,6-trimethyl-1,3,5,2,4,6-trioxatriborinane (3) (4m.mol), sodium carbonate (2.4 m.mol) and tetrakis (triphenylphosphine) palladium(0) (0.09 m.mol) and the reaction was degassed with nitrogen for 15 minutes The mixture was heated at 95⁰C in a pressure tube for 12 h. The reaction mixture was cooled and was quenched with water (15 ml) and the mixture was extracted with ethyl acetate (2 x 15 ml). The combined organic extracts were dried with sodium sulfate and concentrated under reduced pressure to afford 2-fluoro-4-methyl-1-nitrobenzene (4) (83percent yield) as a yellow solid.

Melting Point: 53-54⁰C

¹H NMR (CDCl₃-d_1, δ ppm, 400 M.Hz) δ 7.05 (1H,d,C_H-F), 7.3( 1H, d, J=8.3 HZ), 8.2 (1H,d, J=8.3 HZ), 2.3 (3H,S, -CH₃) The EIMS m/z values and corresponding percentage were as follows: 156 (M+H 100%), 157 (M+1, 7.6%) . IR(KBr,cm-¹): 3100 cm^-1 (ArC-H stret), 1620 cm^-1 (C=C Stret), 1340 cm^-1 ( C-F Stretching),2900 cm^-1 (SP³C-H Stretch), 1525 and1350 cm^-1 ( doublet, N-O Stretching in nitro group), 1160 cm^-1 (C-N Stretching) Wave numbers respectively.

Synthesis of methyl 3-(3-bromophenyl)-3-(5-methyl-2-nitrophenylamino) propanoate (6) [39] :

The mixture of 2-fluoro-4-methyl-1-nitrobenzene (4) (1 m.mol) and methyl 3-amino-3-(3-bromophenyl) propanoate (5) (1 m.mol,) in water (4 ml) was stirred magnetically at 100⁰C (oil-bath) for 3 h (TLC) followed by addition of In (2.5 m.mol.), HOAc (5 m.mol.) and stirring was continued for a further 1 h. The reaction mixture was cooled to room temperature, neutralized (till effervescence ceases) with solid NaHCO₃ and extracted with EtOAc (2 × 5 ml). The combined EtOAc extracts were washed with water (5 ml), dried (Na₂SO₄) and concentrated under rotary vacuum evaporation. The crude product was adsorbed on silica gel (230–400) and purified by flash chromatography (hexane–EtOAc, 90 : 10) to obtain analytically pure product 6 (Yield 52%).

¹H NMR (DMSO-d_6, δ ppm, 400 M. Hz) δ 8 (1H,d, J= 7.2 HZ,Ortho to nitro group), 6.8( 1H, d, J=7.2 HZ, Ortho to methyl group), 2.3 (3H,S,-CH₃), 7.5 (1H,S),7.3-7.5(4H,Ar-H,m),4.6 (1H,t, J=7.3 HZ), 2.9(2H,d, J=7.3 HZ), 3.8(3H,S, O=C-O-CH₃), 3.2 (1H,bs, -NH) The EIMS m/z values and corresponding percentage were as follows: 392(M⁺ 100%), 394 (M+2, 97%) Indicates compound contains one bromine atom present. IR(KBr,cm-¹): 3340 cm^-1 (-N-H Stretch),3100 cm^-1 (ArC-H stret), 1610 cm^-1 (C=C Stret),2900 cm^-1 (SP³C-H Stretch), 1555 and1370 cm^-1 ( doublet, N-O Stretching in nitro group), 550 cm^-1 (C-Br Stretch), 1740 cm^-1 (C=O Strtch in Ester group), 1150 cm^-1 (C-O Stretching), Wave numbers respectively.

Synthesis of 4-(3-bromophenyl)-7-methyl-4,5-dihydro-1H-benzo[b][1,4]diazepin-2(3H)-one (7) [40] : Compound (6) (1 m.mol) and iron powder(7 m.mol) and acetic acid(14 m.mol) were suspended in aqueous ethanol(8:2 Ethanol: water) and heated at reflux about 70-80⁰c for 5-6 hrs. Mean time this mixture would be stirred for 1 minute every half hour with a glass rod and the yellow solution become reddish brown slowly. The reaction mixture was cooled to room temperature and alkalinised by addition of concentrated ammonia, insoluble material was removed by filtration through celite and the filtrate was evaporated under reduced pressure. The resulting solid was extracted with Ethyl acetate for column chromatography. Column chromatography was performed using silica gel(200-300 mesh) eluting with ethyl acetate and petroleum ether(3:1 v/v) to give amine 7 as a colourless liquid. Yield 76%

¹H NMR (DMSO-d_6, δ ppm, 400 M.Hz) δ 7 (1H,d, J= 7.2 HZ), 6.5( 1H, d, J=7.2 HZ, Ortho to methyl group), 2.4 (3H,S,-CH₃), 6.5 (1H,S),7.3-7.5(3H,Ar-H,m),4.2 (1H,t, J=7.3 HZ), 2.9(2H,d, J=7.3 HZ), 3.8(1H,bs), 8.2 (1H,bs, -NH) The EIMS m/z values and corresponding percentage were as follows: 392(M⁺ 100%), 394 (M+2, 97%) Indicates compound contains one bromine atom present. IR(KBr,cm-¹): 3340 cm^-1 (-N-H Stretch),3100 cm^-1 (ArC-H stret), 1610 cm^-1 (C=C Stret),2900 cm^-1 (SP³C-H Stretch), 550 cm^-1 (C-Br Stretch), 1680 cm^-1 (C=O Stretch in cyclic amide ring), 1180 cm^-1 (C-N Stretching), Wave numbers respectively.

Synthesis of 4-(3-bromophenyl)-7-methyl-1H-benzo[b][1,4]diazepin-2(3H)-one (8) [41]:

The mixture of 4-(3-bromophenyl)-7-methyl-4,5-dihydro-1H-benzo[b][1,4]diazepin-2(3H)-one (7) (1 m.mol) and potassium peroxomonosulphate (1.5 m.mol) in Methanol, Water (2:1) (10+5 ml) was stirred magnetically at RT for 3 h (TLC) followed by addition of EtOAc (2 × 15 ml). The combined EtOAc extracts were washed with water (15 ml), dried (Na₂SO₄) and concentrated under rotary vacuum evaporation. The crude product was adsorbed on silica gel (230–400) and purified by flash chromatography (hexane–EtOAc, 90 : 10) to obtain analytically pure product 8 (Yield 62%) as a liquid.

¹H NMR (DMSO-d_6, δ ppm, 400 M.Hz) δ 7.6 (1H,d, J= 7.2 HZ), 7.2( 1H, d, J=2 HZ, Ortho to methyl group), 2.4 (3H,S,-CH₃), 9 (1H,d, J=7.2 HZ),7.4-7.95(4H,Ar-H,m), 3.5(2H,S), 8(1H,bs),

The EIMS m/z values and corresponding percentage were as follows: 328(M⁺ 100%), 330 (M+2, 97%) Indicates compound contains one bromine atom present.

IR(KBr,cm-¹): 3340 cm^-1 (-N-H Stretch),3100 cm^-1 (ArC-H stret), 1630 cm^-1 (C=N Stret),2920 cm^-1 (SP³C-H Stretch), 550 cm^-1 (C-Br Stretch), 1680 cm^-1 (C=O Stretch in cyclic amide ring), 1180 cm^-1 (C-N Stretching), Wave numbers respectively.

Synthesis of 4-(3-bromophenyl)-7-methyl-1H-benzo[b][1,4]diazepine-2(3H)-thione [42a] and 4-(3-bromophenyl)-7-methyl-2-(methylthio)-1H-benzo[b][1,4]diazepine (9) [42 b]:

To a solution compound (8) (0.1 m.mol) in 10 ml dry toluene was added P₂S₅ (0.5m.mol). and the mixture was stirred at 70C for 3 h. After cooling at room temperature, the precipitate was removed by ﬁltration and the ﬁltrate was concentrated in vacuo. The residue was puriﬁed by column chromatography onsilicagel(hexane/AcOEt=8/1) to give 4-(3-bromophenyl)-7-methyl-1H-benzo[b][1,4]diazepine-2(3H)-thione as a yellow syrup. YIELD 57% Then A suspension of the 4-(3-bromophenyl)-7-methyl-1H-benzo[b][1,4]diazepine-2(3H)-thione (1 m.mol ) obtained above, K₂CO₃ (2 m.mol), and methyl iodide (2 m.mol) in CH₃CN (5ml) was stirred at 50⁰C for 3 h. After cooling at room temperature, the mixture was concentrated in vacuum. The residue was partitioned between AcOEt (20 ml) and H₂O (15 ml). The organic layer was washed with saturated NaCl Solution (15ml), and dried and concentrated in vacuum. The residue was puriﬁed by column chromatography on silica gel (hexane/ AcOEt=20/1) to give Compound (9) as a yellow syrup. yield 85%

¹H NMR (DMSO-d_6, δ ppm, 400 M.Hz) δ 7.4 (1H,d, J= 7.2 HZ), 7.9( 1H, d, J=7.2 HZ), 2.4 (3H,S,-CH₃), 7 (1H,d, J=2 HZ),7.4-7.95(4H,Ar-H,m), 4.7(1H,S), 4(1H,bs), 2.5 (3H,S,-S-CH₃)

The EIMS m/z values and corresponding percentage were as follows: 358(M⁺ 100%), 360 (M+2, 97%) Indicates compound contains one bromine atom present.

IR(KBr,cm-¹): 3340 cm^-1 (-N-H Stretch),3100 cm^-1 (ArC-H stret), 1630 cm^-1 (C=N Stret),2920 cm^-1 (SP³C-H Stretch), 550 cm^-1 (C-Br Stretch), 1180 cm^-1 (C-N Stretching), Wave numbers respectively.

Synthesis of 4-(3-bromophenyl)-2-hydrazinyl-7-methyl-1H-benzo[b][1,4]diazepine (10) [43] :

To a solution of (9) (1 m.mole) in Ethanol (10 ml), Hydrazine hydrate (98 %) (1.5 m. mole) was added. The mixture was refluxed for four hours. The solvent was evaporated, water (10 ml) was added and the mixture was extracted with chloroform. The solvent was evaporated and the residue was purified from column chromatography. yield 63%

Melting Point : 167-169⁰C

¹H NMR (DMSO-d_6, δ ppm, 400 M.Hz) δ 7.4 (1H,d, J= 7.2 HZ), 7.9( 1H, d, J=7.2 HZ), 2.4 (3H,S,-CH₃), 7 (1H,d, J=2 HZ),7.4-7.95(4H,Ar-H,m), 3.8(1H,S), 4(1H,bs)

The EIMS m/z values and corresponding percentage were as follows: 342(M⁺ 100%), 344 (M+2, 97%) Indicates compound contains one bromine atom present.

IR(KBr,cm-¹): 3340 and 3430 cm^-1 two bands indicates –NH₂ Group), 3100 cm^-1 (ArC-H stret), 1630 cm^-1 (C=N Stret), 560 cm^-1 (C-Br Stretch), 1170 cm^-1 (C-N Stretching), Wave numbers respectively.

Synthesis of 5-(3-bromophenyl)-1,8-dimethyl-3H-benzo[b][1,2,4]triazolo[4,3-d][1,4]diazepine (11) [44]:

To a solution of (10) (1 m.mole) , Tri ethyl ortho acetate (1.5m. mole),acetic acid 2 ml was added. The mixture was refluxed at 120⁰C for 18 hours. The solvent was evaporated, water (10 ml) was added and the mixture was extracted with chloroform. The solvent was evaporated and the residue was purified from column chromatography. yield 75%

Melting Point : 127-129⁰C

¹H NMR (DMSO-d_6, δ ppm, 400 M.Hz) δ 7.4 (1H,d, J= 7.2 HZ), 7.5( 1H, d, J=7.2 HZ), 2.4 (3H,S,-CH₃), 7.6 (1H,d, J=2 HZ), 7.4-7.85(4H,Ar-H,m), 5(1H,S), 10(1H,bs), 2.5 (3H,S)

The EIMS m/z values and corresponding percentage were as follows: 366(M⁺ 100%), 368 (M+2, 97%) Indicates compound contains one bromine atom present.

IR(KBr,cm-¹): 3340 cm^-1 (-N-H Stretch),3100 cm^-1 (ArC-H stret), 1630 cm^-1 (C=N Stret),2920 cm^-1 (SP³C-H Stretch), 540 cm^-1 (C-Br Stretch), 1180 cm^-1 (C-N Stretching) Wave numbers respectively.

Synthesis of methyl 3-amino-3-(3-bromophenyl) propanoate (5) [45] :

3-Bromo Benzaldehyde (1 m.mol), Di ethyl Malonate (2 m.mol) and ammonium acetate (2 m.mol) were added to the solution of anhydrous ethanol (30 ml) and heated to 80⁰C for 17 h. A lot of precipitated solid was filtered and dried in vacuo at 40⁰ C for 24 h to give a light white solid.

Melting Point: 153-154⁰C

Synthesis of 4-(3-(1,8-dimethyl-3H-benzo[b][1,2,4]triazolo[4,3-d][1,4]diazepin-5-yl)phenyl)morpholine (13a), 3-(1,8-dimethyl-3H-benzo[b][1,2,4]triazolo[4,3-d][1,4]diazepin-5-yl)-N-(4-fluorobenzyl)aniline (13b), 1,8-dimethyl-5-(3-(4-(trifluoromethyl)benzylthio)phenyl)-3H-benzo[b][1,2,4]triazolo[4,3-d][1,4]diazepine (13c), 4-(3-(1,8-dimethyl-3H-benzo[b][1,2,4]triazolo[4,3-d][1,4]diazepin-5-yl)phenyl)thiomorpholine (13d), 5-(3-(benzylthio)phenyl)-1,8-dimethyl-3H-benzo[b][1,2,4]triazolo[4,3-d][1,4]diazepine (13e), 5-(3-(4-fluorobenzylthio)phenyl)-1,8-dimethyl-3H-benzo[b][1,2,4]triazolo[4,3-d][1,4]diazepine (13f), 3-(1,8-dimethyl-3H-benzo[b][1,2,4]triazolo[4,3-d][1,4]diazepin-5-yl)-N-(4 (trifluoromethyl)benzyl)aniline (13g) [46] :

A mixture of 5-(3-bromophenyl)-1,8-dimethyl-3H-benzo[b][1,2,4]triazolo[4,3-d][1,4]diazepine (11) (0.1 m.mol), the appropriate nucleophiles 12 (a-e) (0.15 m.mol), K₂CO₃ (0.5 m.mol) in 4 ml aceto nitrile was placed in a sealed vial, The mixture was heated at 90⁰C or 120⁰C using MW irradiation for 30 min, The reaction mixture was diluted with water, extracted with ethyl acetate, dried over sodium sulphate, filtered and evaporated to dryness . The crude product was purified by column chromatography.

Table 2: Characterisation data of 4-(3-(1,8-dimethyl-3H-benzo[b][1,2,4]triazolo[4,3-d][1,4]diazepin-5-yl)phenyl)morpholine (13a), 3-(1,8-dimethyl-3H-benzo[b][1,2,4]triazolo[4,3-d][1,4]diazepin-5-yl)-N-(4-fluorobenzyl)aniline (13b), 1,8-dimethyl-5-(3-(4-(trifluoromethyl)benzylthio)phenyl)-3H-benzo[b][1,2,4]triazolo[4,3-d][1,4]diazepine (13c), 4-(3-(1,8-dimethyl-3H-benzo[b][1,2,4]triazolo[4,3-d][1,4]diazepin-5-yl)phenyl)thiomorpholine (13d), 5-(3-(benzylthio)phenyl)-1,8-dimethyl-3H-benzo[b][1,2,4]triazolo[4,3-d][1,4]diazepine (13e), 5-(3-(4-fluorobenzylthio)phenyl)-1,8-dimethyl-3H-benzo[b][1,2,4]triazolo[4,3-d][1,4]diazepine (13f), 3-(1,8-dimethyl-3H-benzo[b][1,2,4]triazolo[4,3-d][1,4]diazepin-5-yl)-N-(4-(trifluoromethyl)benzyl)aniline (13g)

IR SPECTRAL DATA :

The IR (KBr) spectral data of Synthesised compounds were given in the Table 3

Table: 3 IR data of Synthesised compounds 13 (a-g) :

Comp	M.P. /^oC	Molecular Weight (m/z)	YIELD(%)	Molecular Formula	Found % (Calculated %)
Comp	M.P. /^oC	Molecular Weight (m/z)	YIELD(%)	Molecular Formula	C	H	N
13a	110-112⁰C	374[M+H]	63	C₂₂H₂₃N₅O	70.74(70.76)	6.2(6.21)	18.7(18.73)
13b	143-145⁰C	412[M+H]	62	C₂₅H₂₂FN₅	73(72.98)	5.3(5.4)	16.97(17)
13c	liquid	479[M+H]	65	C₂₆H₂₁F₃N₄S	65.23(65.3)	4.4(4.5)	11.6(11.70)
13d	liquid	412[M+Na]	61	C₂₂H₂₃N₅S	67.5(67.9)	5.93(5.95)	17.92(17.95)
13e	150-152⁰C	411.5[M+H]	60	C₂₅H₂₂N₄S	73.1(73.13)	5.3(5.4)	13.63(13.65)
13f	liquid	429 [M+H]	63	C₂₅H₂₁FN₄S	69.8(70)	4.85(4.95)	12.98(13.07)
13g	liquid	462[M+H]	62	C₂₆H₂₂F₃N₅	67.6(67.7)	4.7(4.8)	15.3(15.2)

Table: 4 ¹H –NMR data of Synthesised compounds 13 (a-g) :

Compound	¹H-NMR (DMSO-d₆) (δ ppm)
13a	δ 7.4 (1H,d, J= 7.2 HZ), 7.5( 1H, d, J=7.2 HZ), 2.4 (6H,S,2× CH₃), 7.6 (1H,d, J=2 HZ), 7-7.5(4H,Ar-H,m), 5(1H,S), 10(1H,bs), 3.2 (4H,m,Ortho to nitrogen atom in morpholine ring),3.7(4H,m, ortho to oxygen atom in morpholine ring)
13b	δ 7.4 (1H,d, J= 7.2 HZ), 7.5( 1H, d, J=7.2 HZ), 2.4 (6H,S,2× CH₃), 7.6 (1H,d, J=2 HZ), 7-7.5(8H,Ar-H,m), 5(1H,S), 10(1H,bs), 4(1H,bs), 4.4(2H,S)
13c	δ 7.4 (1H,d, J= 7.2 HZ), 7.5( 1H, d, J=7.2 HZ), 2.4 (6H,S,2× CH₃), 7.6 (1H,d, J=2 HZ), 7-7.6(8H,Ar-H,m), 5(1H,S), 10(1H,bs), 4(1H,bs), 4.4(2H,S)
13d	δ 7.4 (1H,d, J= 7.2 HZ), 7.5( 1H, d, J=7.2 HZ), 2.4 (6H,S,2× CH₃), 7.6 (1H,d, J=2 HZ), 7-7.5(4H,Ar-H,m), 5(1H,S), 10(1H,bs), 3.8 (4H,m,Ortho to nitrogen atom in thio morpholine ring),2.8(4H,m, ortho to Sulphur atom in thio morpholine ring)
13e	δ 7.4 (1H,d, J= 7.2 HZ), 7.5( 1H, d, J=7.2 HZ), 2.4 (6H,S,2× CH₃), 7.6 (1H,d, J=2 HZ), 7-7.6(9H,Ar-H,m), 5(1H,S), 10(1H,bs), 4(1H,bs), 4.4(2H,S)
13f	δ 7.4 (1H,d, J= 7.2 HZ), 7.5( 1H, d, J=7.2 HZ), 2.4 (3H,S,2× CH₃), 7.6 (1H,d, J=2 HZ), 7-7.6(9H,Ar-H,m), 5(1H,S), 10(1H,bs), 4(1H,bs), 4.3(2H,S)
13g	δ 7.4 (1H,d, J= 7.2 HZ), 7.5( 1H, d, J=7.2 HZ), 2.4 (6H,S,2× CH₃), 7.6 (1H,d, J=2 HZ), 7-7.5(8H,Ar-H,m), 5(1H,S), 10(1H,bs), 4(1H,bs), 4.4(2H,S)

Table: 5 ¹³C –NMR data of Synthesised compounds 13 (a-g) :

Structure of the compound(With numbering)	¹³CNMR (100 M.HZ, DMSO-d_6, δ ppm)
	124, 138, 129, 131, 125, 128, 140, 130, 150, 152, 13, 23, 133, 117, 130, 115, 150, 113, 53, 66 The signals are due to C₁ , C₂ , C₃ , C₄ , C₅ , C₆ , C₇ ,C₈ ,C₉ ,C₁₀ ,C₁₁ ,C₁₂ ,C₁₃ ,C₁₄ ,C₁₅ ,C₁₆, C₁₇ ,C_18,C₁₉, C₂₀ respectively.
	124, 138, 129, 131, 125, 128, 140, 130, 150, 152, 13, 23, 133, 115,130,113, 148, 111, 48, 135, 128,116,160 The signals are due to C₁ , C₂ , C₃ , C₄ , C₅ , C₆ , C₇ ,C₈ ,C₉ ,C₁₀ ,C₁₁ ,C₁₂ ,C₁₃ ,C₁₄ ,C₁₅ ,C₁₆, C₁₇ ,C_18,C₁₉, C_20,C₂₁,C₂₂,C₂₃ respectively.
	124, 138, 129, 131, 125, 128, 140, 130, 150, 152, 13, 23, 133, 125,130,128, 138, 125, 40, 140, 129,126,130,125 The signals are due to C₁ , C₂ , C₃ , C₄ , C₅ , C₆ , C₇ ,C₈ ,C₉ ,C₁₀ ,C₁₁ ,C₁₂ ,C₁₃ ,C₁₄ ,C₁₅ ,C₁₆, C₁₇ ,C_18,C₁₉, C_20,C₂₁,C₂₂,C_23, C₂₄ respectively.
	124, 138, 129, 131, 125, 128, 140, 130, 150, 152, 13, 23, 133, 117, 130, 115, 150, 113, 53, 30 The signals are due to C₁ , C₂ , C₃ , C₄ , C₅ , C₆ , C₇ ,C₈ ,C₉ ,C₁₀ ,C₁₁ ,C₁₂ ,C₁₃ ,C₁₄ ,C₁₅ ,C₁₆, C₁₇ ,C_18,C₁₉, C₂₀ respectively.
	124, 138, 129, 131, 125, 128, 140, 130, 150, 152, 13, 23, 133, 125,130,128, 138, 125, 40, 140, 129,126,130The signals are due to C₁ , C₂ , C₃ , C₄ , C₅ , C₆ , C₇ ,C₈ ,C₉ ,C₁₀ ,C₁₁ ,C₁₂ ,C₁₃ ,C₁₄ ,C₁₅ ,C₁₆, C₁₇ ,C_18,C₁₉, C_20,C₂₁,C₂₂,C_23, respectively.
	124, 138, 129, 131, 125, 128, 140, 130, 150, 152, 13, 23, 133, 125,130,128, 138, 125, 40, 140, 129,126,160 The signals are due to C₁ , C₂ , C₃ , C₄ , C₅ , C₆ , C₇ ,C₈ ,C₉ ,C₁₀ ,C₁₁ ,C₁₂ ,C₁₃ ,C₁₄ ,C₁₅ ,C₁₆, C₁₇ ,C_18,C₁₉, C_20,C₂₁,C₂₂,C_23, respectively.
	124, 138, 129, 131, 125, 128, 140, 130, 150, 152, 13, 23, 133, 115,130,113, 148, 111, 48, 145, 128,124,130,125 The signals are due to C₁ , C₂ , C₃ , C₄ , C₅ , C₆ , C₇ ,C₈ ,C₉ ,C₁₀ ,C₁₁ ,C₁₂ ,C₁₃ ,C₁₄ ,C₁₅ ,C₁₆, C₁₇ ,C_18,C₁₉, C_20,C₂₁,C₂₂,C₂₃ , C₂₄respectively.

BIOLOGICAL ACTIVITY:

Antioxidant activity:

The free radical scavenging activity of the synthesised compounds was studied in vitro by 1,1 di phenyl 2-picryl hydrazyl (DPPH) Assay method [47]. Stock solution of the drug was diluted to different concentrations in the range of 100-200 μg/ml in methanol. Methonalic solution of the synthesised compounds 2 ml was added to 0.003% (w/v) methanol solution of DPPH (1ml) . The mixture was shaken vigorously and allowed to stand for 30 min. Absorbance at 517 nm was determined and the percentage of scavenging activity was calculated. Ascorbic acid was used as the standard drug. The inhibition ratio (I %) of the tested compounds was calculated according to the following equation :

I % = (Ac-As) × 100

Where Ac is the absorbance of the control and As is the absorbance of the Sample. The in vitro scavenging assay of DPPH radicals was performed spectrophotometrically [48] with ascorbic acid as positive control. Percentages of DPPH radical scavenging activity was tabulated in

Table 6 . The percentage scavenging effects of the compound 13e at 100, 150, 200 μg/ml are 51.1,60.8, 68.1 respectively. Ascorbic acid presented a scavenging effect of 98.2% at the concentration of 200 μg/ml . Novel compounds 13e, 13d, 13a showed more antioxidant activity when compared to other compounds in the series. The order of activity was 13e>13d>13a>13f>13b>13c>13g

Table 6 DPPH radical scavenging activity of the tested compounds:

Compound	Scavenging effect (%) Concentration of the tested compounds (μg/ml)
Compound	100	150	200
13a	37	48	53.6
13b	32.2	43.4	54.9
13c	23	33	41.2
13d	51	60.5	68
13e	52	61.7	69.4
13f	35	46.3	52.1
13g	22	32	39
Ascorbic acid	73	86	98.2

RESULTS AND DISCUSSIONS:

Characterization:

The IR spectrum of the title Compounds 13(a-g) has given stretching vibration at 3100cm^-1, due to the stretching vibration corresponding to Ar-H Stretching vibrations. The absorption peak at 2935 cm^-1 is due to The stretching vibration corresponding to the SP³ C-H ( methyl gp).The strong Intensity absorption at 3350cm^-1 is due to The stretching vibration of -NH, 1360 cm^-1 is due to The stretching vibration of C-F in –CF₃ group. The weak Intensity absorption at 1620 cm^-1 corresponds to a C=N Stretching vibration.1150cm^-1 corresponding to C-O Stretching.

It has been observed from chemical structure of compound 13(a-g) that different pair of protons. The protons of Methyl group which is attached to benzene ring appeared as a singlet at δ =2.3 ppm, The protons of methylene group appeared as a multiplet at δ =3.8 ppm,. The protons attached benzene ring appeared between δ =7.5-7.9 ppm respectively. The chemical shifts of the final compound carbon vary from δ = 165to 23 ppm. The carbon nucleus under the influence of a strong electronegative environment appeared down field, The carbon chemical shift of the methyl group at δ= 23ppm. The carbon chemical shift of the Tri Fluoro methyl group at δ= 125 ppm. Readily available starting materials and simple synthesizing procedures make this method very attractive and convenient for the synthesis of 1,5 Benzo di azepine derivatives. Formation of products was confirmed by recording their Elemental analysis,¹H NMR, ¹³C, FT-IR, mass spectra. The Elemental analysis data showed good agreement between the experimentally determined values and the theoretically calculated values with in ±0.4% .

Anti oxidant screening:

The results of Anti oxidant studies of newly synthesized compounds reveal that the compounds possess significant Antioxidant activities. The results of these studies are given in Table 6. From Anti Oxidant screening results, it has been observed that compounds 13e and 13d possess good activity.

CONCLUSION:

Hetero cyclic compound containing 1, 5- Benzodiazepine nucleus plays most important role in the field of clinical therapeutics. It shows wide range of activities for medication purpose. Vast number of 1, 5-Benzodiazepines containing compounds have been synthesized and evaluated for their biological activity. In conclusion, a series of new 1, 5-Benzodiazepines analogs 13 (a-g) were synthesized in good yield, Characterized by different spectral studies and their antioxidant activity have been evaluated. Among the synthesized compounds 13e, 13d showed excellent antioxidant activity, Electron withdrawing group –-CF₃ showed less antioxidant activity when compared to other compounds in the series. [Table 6].

ACKNOWLEDGEMENT:

The authors are thankful to Sri Krishnadevaraya University, Anantapuramu for providing Research facilities.

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Received on 06.02.2016 Modified on 17.02.2016

Asian J. Research Chem. 9(2): Feb., 2016; Page 89-98

DOI: 10.5958/0974-4150.2016.00017.1