International Journal of Green and Herbal Chemistry

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108 IJGHC; 2012, Vol.1, No.2, 108-119.

E-ISSN: 2278-3229

International Journal of Green and Herbal Chemistry

Available online at www.ijghc.org

Green Chemistry

IJGHC; June-August, 2012; Vol.1.No.2, 108-119Research Article

Microwave Assisted Synthesis of Novel Benzotriazole

- Pyrazoline derivatives and its Pharmacological

EvaluationKalmendra Singh Sisodiya

1*, Manisha

2, Amit Sahu

3, V.K.Sharma

4and Bharat Parashar

5

1Department of Chemistry, Pacific University, Udaipur, India.

2Skyline Institute of Engineering and Technology, Greater Noida (U.P.), India3Department of Chemistry, Techno India NJR instituted of technology Udaipur, India

4Department of Chemistry, M.L. Sukhadia University, Udaipur, (Rajasthan)5Department of pharmaceutics, M.B.University; Solan (H.P.).

Received: 13 March 2012; Revised: 31 March 2012; Accepted: 8 April 2012

Abstract:A solvent free approach for organic synthesis is described here which

involve microwave exposure of neat reactants. A novel and simple method have

been developed for the synthesis of some Benzotriazole - Pyrazoline derivatives

under microwave irradiation. In addition, these compounds were obtained with

conventional heating procedures and microwave irradiation to compare them

with those obtained with solid support synthesis. All the compounds synthesized

were characterized by running TLC, Elemental analysis, IR, NMR and MS

spectra. Consequently, the solid support synthesis method provided nearly the

same and higher product yields in a very short period of time. These results

suggest that in addition, the use of solid supports in conjunction with microwave

leads to a higher yield, remarkable reactions rate enhancement and high

catalytic activity with the optimum utilization of energy. Solid support synthesis

method is more useful than the microwave irradiation method and conventional

method.

Keywords: Green chemistry, microwave irradiation, solid supported synthesis,

benzotriazole - pyrazoline derivatives, neat reaction technology


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109 IJGHC; 2012, Vol.1, No.2, 108-119.

INTRODUCTION

Classical methods require elaborate apparatus setup, longer heating time and large volume of organic

solvents and there is virtually no control over the energy input. Hazardous chemicals and by products of

various reactions increasing pollution in the environment. Keeping in view the need for avoiding

hazardous chemicals and solvents in chemical reactions, microwave technique was found to beaccelerating a wide variety of transformations.Neat reaction technology is a step forward in the direction

of solvent free reactions and an alternative approach that eliminates the use of a solid support as well as

solvent from the reaction. In recent years design of environmentally benign reactions is an important goal

in organic synthesis. Microwave induced Organic Reaction Enhancement (MORE) chemistry offers a

simple, non-conventional technique for the synthesis of a wide variety of compounds having medicinal,

pharmaceutical and commercial importance. In this expeditious and solvent free approach the reactants

were adsorbed over inorganic supports and exposed to microwave irradiation. In recent years the use of

microwaves1,2

has been well established as a pollution free technique which allows reaction to occur on a

preparative scale in open vessels under solvent free conditions which avoids the risk of high pressures and

explosions.Microwave activation rather than conventional heating is preferred, as solid supports are rather

poor thermal conductors but strong microwave absorbents, which results in lesser evaporation of solvents

preventing pollution3.

Further the reactions are generally faster and the products obtained are of high

purity4, 5

.

Pyrazole as well as pyrazolines containing compounds have been reported to show a broad spectrum of

biological activities such as antimicrobial6-9

, anti-tumor10,

and antiinflammatory11, 12

agents. Due to

bioactivity associated with pyrazole and pyrazolines containing compounds, researchers and chemist are

very much interested in pyrazole chemistry13-15

. Pyrazolone are associated with broad spectrum of

biological activities16

, Pyrazolone exhibit anti-inflammatory17

and analagics activity18

, anticancer

activity19

,20

antiamoebic activity21

, antitubercular activity22

and antitumor activity23

.

Synthesis of some Benzotriazole - Pyrazoline derivatives under microwave irradiation using diethylmalonate, acetyl acetone, 1- Chloro-hexane 2-4 dione, ethyl 2-cyanoacetate and phenyl isothiocynate by

solid support synthesis method, conventional heating procedures and microwave irradiation method were

done. The reaction carrierd out in absolute alcohol or DMF using conventional method required 4-10 h,

while microwave irradiation method require only 3.30-7 min and solid support method using silica gel

require only 4-6.50 min. The synthetic route of above mentioned compound is shown in Scheme 1,

(Table 1).

MATERIALS AND METHODS

Experimental Section: All the irradiation was carried out in a modified microwave oven (Kenstar, model

no: OM26.EGO). Melting points of synthesis compounds were determined in open capillaries in liquid

paraffin and are uncorrected. Purity of the compounds in addition to elemental analysis were verified by

percolated TLC using silica gel G as a adsorbent using ethyl acetate: n-hexane (7:3) as a eluent and spot

was detected by using iodine vapours. The IR (KBr pellets) spectra were recorded on a Perkin Elimer-

1800- spectrophotometer and H1NMR spectra were recorded on BRUKER DRX-300MHz

spectrophotometer, (TMS as a internal reference) and chemical shifts are expressed in . Mass spectra

were recorded on Jeol D30 spectrophotometer. Elemental analyses for C, H and N were conducted using a

Perkin -Elmer C, H, and N analyzer. Their result was found to be an in good agreement with the

calculated values (0.4%).

Synthesis of ethyl 2-(1H-benzo[d][1,2,3]triazol-1-yl) acetate (I)

Conventional Method: A mixture of Benzotriazole (0.01 mol), ethyl chloro acetate ( 0.01 mol) and

potassium carbonate 3.0 gm in acetone 50.0 mL was stirred for 6 hours. Completion of reaction was 5


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110 IJGHC; 2012, Vol.1, No.2, 108-120.

Synthesis of Compound (I) and (II)

HN

N

N

O

O

Cl

O

O-

N

NN

+K2CO3

O

NHH2N

N

NN

NH2NH2.H2O

( I ) (II)

Scheme No. 1

CH2(COOC2H5)2

CH3COCH

2COCH3

ClCH2COC

H2COCH2

CH3

CNCH2COOCH

2CH3

(ii)ClCH2COOC2H5

(i)Morpholine

CH2(C

OOC2H

5)2

CH3C

OOH

C6H5NCS

CH

3COCH

2COCH

2CH

3

Scheme-2

(2)

(1)

(8)

(7)

(6)

(5)

(4)

(3)

N

N

OO

N

N N

H2N

1-(2-(1H-benzo[d][1,2,3]triazol-1-yl)acetyl)-3-methyl-1H-pyrazol-5(4H)-

one

N

N

O

H3C

O

N

NN

1-(2-(1H-benzo[d][1,2,3]triazol-1-yl)acetyl)-3-amino-1H-pyrazol-5(4H)-one

1-(2-(1H-benzo[d][1,2,3]triazol-

1-yl)acetyl)-3-(chloromethyl)-1H-pyrazol-5(4H)-one

N

N

O

Cl

O

N

N

N

N

N

H3C

O

N

NN

CH3

2-(1H-benzo[d][1,2,3]triazol-1-yl)-1-(3,5-dimethyl-4,5-

dihydropyrazol-1-yl)ethanone

N

HN

O

O

O

N

NN

1-(2-(1H-

benzo[d][1,2,3]triazol-1-yl)acetyl)pyrazolidine-3,5-dione

1-(2-(1H-benzo[d][1,2,3]triazol-1-yl)acetyl)-2-acetylpyrazolidine-3,5-

dione

N

N

O

O

O

O

N

NN

1-(2-(1H-benzo[d][1,2,3]triazol-1-yl)acetyl)-4-phenylthiosemicarbazide

HN

NH S

HN

O

NN

N

(E)-N-(4-oxo-2-(phenylimino)thiazolidin-3-yl)-1H-benzo[d][1,2,3]triazole-1-

carboxamide

NN

NO

NH

S

N

N

O

2-(1H-benzo[d][1,2,3]triazol-1-

yl)acetohydrazide

O

NH

H2N

N

NN

(II)

The synthetic route of compounds (1-8)


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Table: 1- Comparative Analysis of Conventional and Microwave Methods

A.A= Acetic acid

Synthesis of 1-(2-(1H-benzo[d][1,2,3]triazol-1-yl) acetyl)pyrazolidine-3,5-dione. (1)

Conventional Method: A mixture of (II) (0.01 mol), diethyl malonate (0.01mol) and two to three drops of

glacial acetic acid were taken in a round bottom flask in 50 mL of ethyl alcohol and was refluxed for

about 6 hr on a water bath. After completion of the reaction as indicated by TLC, the reaction mixture was

cooled and treated with ice cold water. The brown colour oily mass obtained was cooled and the crud

product was recrystallized from ethanol to give afford 1. Physical characteristic of compound is recorded

in Table No 1.

Microwave Method in solvent: A mixture of (II) (0.01 mol), diethyl malonate (0.01mol) and two to

three drops of glacial acetic acid in 30 mL of ethyl alcohol was subjected to microwave irradiation at 360

W for 3 min with an intermittently at 30 sec intervals. After completion of the reaction as indicated by

TLC, the reaction mixture was cooled and treated with cold water. The brown colour oily mass obtainedwas cooled and the crud product was recrystallized from ethanol to give afford 1. Physical characteristic

of compound is recorded in Table No 1.

Solid Support Method: A mixture of (II)(0.01 mol), diethyl malonate (0.01mol) were dissolve in alcohol

and the mixture was absorbed on acidic alumina and was subjected to microwave irradiation at 500 W for

5.10 min with an intermittently at 10 sec intervals. After completion of the reaction as indicated by TLC,

the compound was separate out from di ethylethane and recrystallise from ethyl alcohol. Physical

characteristic of compound is recorded in Table No 1.

Physical and Elemental Analysis of Compound 1: Mol. Wt.259; M.P. 172-174 C; Yield: 88 %; Rf

:0.64; IR ( KBr cm

-1

): 3303 (-NH), 3035 (Aromatic CH-Ar. str. ), 2260 (N=N), 1735, 1730,1666,(C=O), ;

1H NMR (400 MHz, DMSO-d6) : 7.45- 7.80 (4H, m, Ar-H); 8.70 (s, H, NH), 4.75 (s,

Comp Molecular

formula

M.wt Condition Conventional

method

Microwave method m.

poC

Rf

In solvent On SolidSupport

Yield

(%)

R time(h) Yield

(%)

R time

(min)

Yield

(%)

R time

(min)

1 C11H9N5O3 259 A.A 70 6.00 82 3.00 88 6.10 17

2

0.64

2 C13H11N5O4 301 A.A 68 5.10 80 5.10 86 6.30 18

9

0.62

3 C13H13N5O 257 - 71 8.10 84 3.10 90 3.30 16

9

0.68

4 C12H10ClN5O2 291 - 72 5.22 81 3.30 88 5.30 20

1

0.61

5 C12H11N5O2 257 A.A 71 6.12 83 3.00 90 5.20 169

0.68

6 C11H10N6O2 258 - 73 4.55 84 3.00 92 2.20 18

2

0.66

7 C15H14N6OS 326 - 69 4.11 82 2.00 90 2.10 21

0

0.66

8 C16H12N6O2S 352 Morpholin

e

70 5.50 80 2.30 86 3.10 23

2

0.66


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112 IJGHC; 2012, Vol.1, No.2, 108-120.

2H, CH2 ) , 3.35 (s, 2H, CH2), MS (m/z+) [M+] 259; Anal.Calc.for C11H9N5O3; C, 50.97; H, 3.50; N,

27.02; Found: C, 51.26.; H, 3.30; N, 26.82.

Synthesis of 1- (2- (1H-benzo [d][1,2,3] triazol-1-yl)acetyl) -2-acetylpyrazolidine -3,5-dione

(2)

Conventional Method: A mixture of (II) (0.01 mol) and diethyl malonate (0.01 mol) in glacial aceticacid (5 mL) were taken in a round bottom flask and was refluxed for about 5 hr on a water bath . After

completion of the reaction as indicated by TLC, the reaction mixture was cooled and treated with cold

water. The solid that precipitated was filtered, washed with water and recrystallized from ethanol to

afford 2. Physical characteristic of compound is recorded in Table No 1.

Microwave Method in solvent: A mixture of (II) (0.01 mol) and diethyl malonate (0.01 mol) in glacial

acetic acid (5 mL) was subjected to microwave irradiation at 360 W for 5.10 min with an intermittently at

20 sec intervals. After completion of the reaction as indicated by TLC, the reaction mixture was cooled

and treated with cold water. The solid that precipitated was filtered, washed with water and recrystallized

from ethanol to afford 2. Physical characteristic of compound is recorded in Table No 1.

Microwave Method on Solid Support: Compound (II) (0.01 mol) and diethyl malonate (0.01 mol) were

dissolved in acetone and the solution was absorbed on acidic alumina and was subjected to microwave

irradiation at 500 W for 4.30 min with an intermittently at 10 sec intervals . After completion of the

reaction as indicated by TLC compound was separate out from acetone and allows drying. Product was

recrystallised with di methyl ether to afford 2. Physical characteristic of compound is recorded in Table

No 1.

Physical and Spectral Analysis of Compound 2: Mol. Wt.301; M.P. 189-191 C; Yield: 86 %; Rf :0.62;

IR ( KBr cm-1

): 3130 (Aromatic CH-Ar, str. ), 2270 (N=N), 1740,1693, 1670, 1640, (C=O), ;1H NMR

(400 MHz, DMSO-d6) : 7.32- 7.82 (4H, m, Ar-H); 4.60 (s, 2H, CH2 ) , 3.30 (s, 2H, CH2), 2.40 (s, 3H,

CH3) : MS (m/z+) [M

+

] 301; Anal. Calc.for C13H11N5O4; C, 51.83; H, 3.68; N, 23.25; Found: C,52.06.; H, 4.02; N, 23.72;

Synthesis of 2- (1H-benzo [d][1,2,3 ]triazol-1-yl) -1- (3,5-dimethy l-4,5-dihydropyrazol-1-yl)

ethanone(3)

Conventional Method: A mixture of 2-(1H-benzo[d][1,2,3]triazol-1-yl) acetohydrazide (II) (0.01 mol)

and acetyl acetone (0.01 mol) was taken in Erlenmeyer flask. The mixture was well stirred and then taken

in a round bottom flask and was refluxed for about 2 hr on a water bath. After completion of the reaction

as indicated by TLC the reaction- mixture was then allowed to stand at RT and the product formed was

washed with cold water and dissolved in methanol then filtered, dried and recrystallized from ethanol to

afford 3. Physical characteristic of compound is recorded in Table No 1.

Microwave Method in solvent: A mixture of 2-(1H-benzo[d][1,2,3]triazol-1-yl) acetohydrazide (II) (0.01

mol) and acetyl acetone (0.01 mol) was taken in Erlenmeyer flask. The mixture was well stirred subjected

to microwave irradiation at 360 W for 3.10 min with an intermittently at 10 sec intervals. After

completion of the reaction as indicated by TLC the reaction- mixture was then allowed to stand at RT and

the product formed was washed with cold water and dissolved in methanol then filtered, dried and

recrystallized from ethanol to afford 3. Physical characteristic of compound is recorded in Table No 1.

Microwave Method on Solid Support: A solution of (II) (0.01 mol) and acetyl acetone (0.01 mol) were

taken in beaker. The mixture was well stirred and then absorbed on neutral alumina and was subjected to

microwave irradiation at 500 W for 3.10 min with an intermittently at 20-25 sec intervals. After

completion of the reaction as indicated by TLC the compound was separate out from acetone and

recrystallized from ethanol to afford 3. Physical characteristic of compound is recorded in Table No 1.


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IR ( KBr cm-1

): 3110 (Aromatic CH-Ar, str. ), 2265 (N=N), 1690, (C=O), 1553(C=N), :1H NMR (400

MHz, DMSO-d6) : 7.32- 7.82 (4H, m, Ar-H); 5.71(s, 1H, CH) , 4.56 (s, 2H, CH2 ) , 3.42 (s, 2H, CH2),

3.35 (s, 3H, CH3), 2.40 (s, 3H, CH3 ): MS (m/z+) [M+] 257 ; Anal. Calc.for C13H13N5O; C, 60.69; H,

5.88; N, 27.22; Found: C, 60.92; H, 5.62; N, 27.50.

Synthesis of 1-(2-(1H-benzo[d][1,2,3]triazol-1-yl)acetyl)-3-(chloromethyl)-1H-pyrazol-

5(4H)-one (4)

Conventional Method: A mixture of (II) (0.01 mol), 1- Chloro-hexane 2-4 dione (0.012 mol) was taken

in a round bottom flask and was refluxed for about 5 hr on a water bath. TLC monitored the reaction.

After completion of the reaction, reaction- mixture was allowed to stand at RT and the product formed

was filtered, washed with water, dried and recrystallized from ethanol to afford 4. Physical characteristic


Microwave Method in solvent: A mixture of (II) (0.01 mol), 1- Chloro-hexane 2-4 dione (0.07 mol) was

taken in a borosil beaker (100 mL). The well-stirred mixture was irradiated inside the microwave oven for

a period of 3.30 minutes (at 480 W). TLC monitored the reaction. After completion of the reaction,reaction- mixture was allowed to stand at RT and the product formed was filtered, washed with water,

dried and recrystallized from ethanol to afford 4. Physical characteristic of compound is recorded in Table

No 1.

Microwave Method on Solid Support: Compound (II) (0.01 mol), 1- Chloro-hexane 2-4 dione (0.07

mol) were dissolved in alcohol and the mixture was absorbed on neutral alumina and was irradiated inside

the microwave oven for a period of 5.30 minutes (at 500W). TLC monitored the reaction. After

completion of the reaction, product was separate out from aceton recrystallized from ethanol to afford 4.

Physical characteristic of compound is recorded in Table No 1.

Physical and Spectral Analysis of Compound 4: Mol. Wt.291; M.P. 201-122 C; Yield: 88 %; Rf :0.61;IR ( KBr cm

-1): 3080 (Aromatic CH-Ar str. ), 2240 (N=N), 1695,1666 (C=O), 1606 (C=N), :

1H NMR

(400 MHz, DMSO-d6) : 7.7-7.8(m, 4H,), 2.80 (s, 2H, CH2), 3.45 (s, 2H, CH2): 7.32- 7.82 (4H, m, Ar-H);

5.71(s, 1H, CH) , 4.30 (s, 2H, CH2 ) , 3.22 (s, 2H, CH2), : MS (m/z+) [M+] 291 ; Anal. Calc.for C12H10

ClN5O2; C, 49.41; H, 3.46; N, 24.01; Found: C, 49.64; H, 3.16; 1-; N, 24.24.

Synthesis of 1-(2-(1H-benzo[d][1,2,3]triazol-1-yl)acetyl)-3-methyl-1H-pyrazol--(4H)-one (5)

Conventional Method: Compound (II), hexane-2, 4-dione (0.01 mol), and (0.005 mol) acetic acid was

mixed thoroughly. This mixture was taken in a round bottom flask and was refluxed for about 6 hr on a

water bath. Upon completion of the reaction (monitored by TLC), the reaction mixture was poured onto

crushed ice. The solid mass obtained was filtered and washed several times with water. Purification by

recrystallization with alcohol gave product 5. Physical characteristic of compound is recorded in Table

No 1.

Microwave Method in solvent: Compound (II), hexane-2, 4-dione (0.01 mol), and (0.00- mol) acetic

acid was mixed thoroughly. This mixture was subjected to microwave irradiation (by keeping inside a

microwave oven) for 3.0 min at 480 W power levels with intermitted irradiation for 30 second. Upon

completion of the reaction (monitored by TLC), the reaction mixture was poured onto crushed ice. The

solid mass obtained was filtered and washed several times with water. Purification by recrystallization

with alcohol gave product 5. Physical characteristic of compound is recorded in Table No 1.

Microwave Method on Solid Support: Compound (II), hexane-2,4-dione (0.01 mol), were dissolved in

acetone and absorbed on acidic alumina and irradiated inside the microwave oven for a periodof 5.20 minat 500 W power levels with intermitted irradiation for 30 second. Upon completion of the reaction

(monitored by TLC), the reaction mixture was poured onto crushed ice. The solid mass obtained was


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filtered and washed several times with water. Purification by recrystallization with alcohol gave product 5.


Physical and Spectral Analysis of Compound 5: Mol. Wt.257; M.P. 169-171 C; Yield: 90 %; R f :0.68;

IR ( KBr cm-1

): 3115 (Aromatic CH-Ar str. ), 2262 (N=N), 1680, 1606 (C=O), 1530 (C=N), ;1H

NMR (400 MHz, DMSO-d6) : 7.40- 7.88 (4H, m, Ar-H); 4.56 (s, 2H, CH2 ) , 3.42 (s, 2H, CH2), 3.35 (s,

3H, CH3), : MS (m/z+) [M+] 257 ; Anal. Calc.for C12H11N5O2; C, 56.03; H, 4.31; N, 27.22; Found: C,

56.36; H, 4.64; N, 27.46.

Synthesis of 1-(2-(1H-benzo[d][1,2,3]triazol-1-yl)acetyl)-3-amino-1H-pyrazol--(4H)-one (6)

Conventional Method: 2-(1H-benzo[d][1,2,3]triazol-1-yl) acetohydrazide (0.01 mol) (II)and (0.01) and

ethyl 2-cyanoacetate (0.01) in -0 mL ethanol were taken in a round bottom flask and was refluxed for

about 4hr on a water bath and reaction progress was monitored by TLC. Then crude product so obtained

was poured into ice-cold water, filtered, dried, and recrystallized from methanol to give product 6.


Microwave Method in solvent: 2-(1H-benzo[d][1,2,3]triazol-1-yl) acetohydrazide (0.01 mol) (II) and

(0.01) and ethyl 2-cyanoacetate (0.01) were mixed together to form a paste and then subjected to

microwave irradiation for 3.0 min at 400 W power level and reaction progress was monitored by TLC.

Then crude product so obtained was poured into ice-cold water, filtered, dried, and recrystallized from

methanol to give product 6. Physical characteristic of compound is recorded in Table No 1.

Solid Support Method: 2-(1H-benzo[d][1,2,3]triazol-1-yl) acetohydrazide (0.01 mol) (II) and (0.01) and

ethyl 2-cyanoacetate (0.01) were dissolved in alcohol and absorbed on alumina. The mixture was

subjected to microwave irradiation at 500 W for 4.20 min with an intermittently at 30-35 sec intervals.

After completion of the reaction indicated by TLC the compound was separate out from acetone and

recrystallize from alcohol to give product 6. Physical characteristic of compound is recorded in

Table No 1.Physical and Spectral Analysis of Compound 6: Mol. Wt.258; M.P. 182-183 C; Yield: 92 %; Rf :0.66;

IR ( KBr cm-1

): 3334, 3218(-NH2), 3140 (Aromatic CH-Ar str. ), 2262 (N=N), 1698, 1672 (C=O),

1554 (C=N), ;1H NMR (400 MHz, DMSO-d6) : 7.46- 7.68 (4H, m, Ar-H); 5.12 (s, 2H, NH2), 4.50 (s,

2H, CH2 ) , 3.42 (s, 2H, CH2),: MS (m/z+) [M+] 258 ; Anal. Calc.for C11H10N6O2; C, 51.16; H, 3.90; N,

32.54; Found: C, 51.36; H, 4.20; N, 32.74.

Synthesis of 1-(2-(1H-benzo[d][1,2,3]triazol-1-yl)acetyl)-4-phenylthiosemicarbazide (7)

Conventional Method: To a mixture of 2-(1H-benzo[d][1,2,3]triazol-1-yl) acetohydrazide (II) (0.01 mol )

and phenyl isothiocynate (0.01 mol e) in a 40 ml DMF was were taken in a round bottom flask and was

refluxed for about 4 hr on a water bath. TLC examined the progress of the reaction. The mixture waspoured into ice-cold water. The resulting solid was filtered, dried and recrystallized from benzene to give

product 7. Physical characteristic of compound is recorded in Table No 1.

Microwave Method in solvent: To a mixture of 2-(1H-benzo[d][1,2,3]triazol-1-yl) acetohydrazide (II)

(0.01 mol ) and phenyl isothiocynate (0.01 mol e) in a 20 ml DMF was taken in Erlenmeyer flask. The

mixture was irradiated under microwave for 2.00 min at 360 W powers with intermittent radiation of 15

sec interval. TLC examined the progress of the reaction. The mixture was poured into ice-cold water. The

resulting solid was filtered, dried and recrystallized from benzene to give product 7. Physical

characteristic of compound is recorded in Table No 1.

Microwave Method on Solid Support: 2-(1H-benzo[d][1,2,3]triazol-1-yl) acetohydrazide (II) (0.01 mol)

and phenyl isothiocynate (0.01 mol) were dissolved in acetone and the mixture was absorbed on neutral

alumina and was subjected to microwave irradiation at 500 W for 5.10 min with an intermittently at 15-20

sec intervals. After completion of the reaction the compound was separate out from acetone and


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115 IJGHC; 2012, Vol.1, No.2, 108-119.

recrystallize from alcohol to give product 7. Physical characteristic of compound is recorded in

Table No 1.

Physical and Spectral Analysis of Compound 7: Mol. Wt.326; M.P. 210-2111 C; Yield: 90 %; Rf

:0.66; IR ( KBr cm-1

): 3416,3372, 3312(-NH), 3089 (Aromatic CH-Ar str. ), 2262 (N=N), 1708 (C=O),

1100 (C=S), ;1H NMR (400 MHz, DMSO-d6) : 10.20 (s,H, HN-CO), 7.48- 7.80 (m, 9H, Ar-H); 4.34

(s,H,HN-Ph), 3.42 (s, 2H, CH2), 2.20 (s,H,HN-N); : MS (m/z+) [M+] 326 ; Anal. Calc.for; C15H14N6OS

; C, 55.20; H, 4.32; N, 25.75; Found: C, 55.20; H, 4.32; N, 25.75.

Synthesis of (E) -N- (4-oxo-2-(phenylimino) thiazolidin-3-yl)-1H-benzo[d][1,2,3]triazole-1-

carboxamide(8)

Conventional Method: A mixture of7 (0.01 mol) and ethylchloroacetate in presence of catalytic amount

of morpholine in 40 mL of ethanol were taken in a round bottom flask and was refluxed for about 5.50 hr

on a water bath. After completion of the reaction as indicated by TLC, the reaction mixture was cooled

and treated with ice-cold water and recrystallized from ethanol to give product 8. Physical characteristic


Microwave Method in solvent: A mixture of7 (0.01 mol) and ethylchloroacetate in presence of catalytic

amount of morpholine were mixed thoroughly. Than the mixture was irradiated under microwave oven for

2.30 min at 480 W with an intermitted irradiation for 30sec. interval. After completion of the reaction as

indicated by TLC, the reaction mixture was cooled and treated with ice-cold water and recrystallized from

ethanol to give product 8. Physical characteristic of compound is recorded in Table No 1.

Microwave Method on Solid Support: A mixture of 7 (0.01 mol) and ethylchloroacetate were mixed

thoroughly and dissolved in alcohol and the mixture was absorbed on basic alumina and subjected to

microwave irradiation at500 W for 4.10 min with an intermittently at 15-20 sec intervals. After

completion of the reaction as indicated by TLC the compound was separate out from acetone and 1,2

dichloro methane. Physical characteristic of compound is recorded in Table No 1.


IR ( KBr cm-1

): 3080 (Aromatic CH-Ar str. ), 2282 (N=N), 1698, 1649 (C=O), 740 (S-C-S), ;1H NMR

(400 MHz, DMSO-d6) : 10.20 (s, H, HN-CO), 9.67(s, H, HN) , 7.32- 7.88 (m, 9H, Ar-H); 4.10 (s, 2H,

CH2), : MS (m/z+) [M+] 352 ; Anal. Calc. for; C16 H12 N6 O2 S; C, 54.54; H, 3.43; N, 23.85; Found: C,

54.74; H, 3.24; N, 23.62.

BIOLOGICAL ASSAY

All the newly synthesized compounds were tested in vitro for antimicrobial activity against four bacterial

strains two-gram positive bacteria (Bacillus subtilis and staphylococcus aureus) and two-gram negativebacteria (Escherichia coli and P.aeruginosa) and antifungal activity against Candida albicans and

Asperigillus nigerat the concentration of 200,100,50, g/ml by using the cup plate agar disk diffusion

method24

,25

and determination of minimum inhibitory concentration (MIC) by broth dilution method.The

concentration used in screening was choosen after determining MIC of each compound. The

dimethylsulfoxide (DMSO) was used as a solvent. For this method, Mueller-Hinton agar was used as the

growth medium for the bacterial strains and Sabouraud agar was growth medium for fungal species. The

sterilized agar media were poured in to petridishes and allow solidifying. On the surface of the media

microbial suspension were spread with the help of sterilized triangular loop. (Inoculums of standard

suspension 0.1 mL of the test organism strain which contains 106 bacilli/mL)

A stainless steel cylinder of 9 mm diameter (pre sterilized) was used to bore the cavities. In to these wellwere added 0.1mL portion of the test compounds in solvent DMSO. The drug solution was allowed to

diffuse for about an hour in to the medium. The petridishes used for antibacterial screening were


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116 IJGHC; 2012, Vol.1, No.2, 108-120.

incubated at 37 1C for 24 h, while those for antifungal activity were incubated at 28 1C for 48-72 h.

DMSO was used as a control for all the type of microorganisms. The control showed no activity against

the strains of microorganisms used. Antimicrobial activity and antifungal activity was measured as a

function of diameter of zone of inhibition (mm). The result was compared with standard drugs

Ciprofloxacin for antibacterial activity and fluconazole for antifungal activity by measuring the zone of

inhibition in mm at 200,100 and 50 g/mL (Table -2 and Table-3). The lowest concentration, whichshowed no visible growth, was taken as an end point minimum inhibitory concentration (MIC). For

antibacterial activity, in present protocol 50 g/ml is considered as active as compared to the standard

drug Ciprofloxacin. For antifungal activity, 50 g/mL is considered as active as compared to standard

fluconazole

Table: 2. Antifungal Activities of the synthesized compounds (1-8).

Antifungal activity

Compounds C. albicans A. niger

50g

/ml

100

g/ml

200

g/ml

50g

/ml

100g

/ml

200g

/ml1 - ++ +++ - ++ ++

2 + ++ ++++ ++ +++ ++++

3 - ++ +++ - ++ +++

4 + ++ ++ + ++ ++

5 ++ ++ ++ ++ ++ ++

6 ++ +++ +++ ++ ++ +++

7 ++ +++ +++ +++ +++ +++

8 + +++ +++ - ++ +++

Fluconazole ++++ ++++ ++++ ++++ ++++ + + + +(-)< 6mm; (+) = 7 - 10 mm; (++) =11 15 mm; (+++) = 16 - 21mm; (++++) = 22 - 28mm.

RESULTS AND DISCUSSIONS

The compound ethyl 2-(1H-benzo[d][1,2,3]triazol-1-yl) acetate (I) was synthesized by microwave

radiation of mixture of Benzotriazole, ethyl chloro acetate and potassium carbonate in acetone. The M.P.

of the synthesized compound was checked by the given literature. The compound 2-(1H-

benzo[d][1,2,3]triazol-1-yl) acetohydrazide (II) was synthesized byethanolic solution of compound (I)

and hydrazine hydrate under microwave radiation of 240W. The purity of the compound was analyzed by

TLC using ethyl acetate: n-hexane (7:3) as a mobile phase. The final compounds (1-8) were synthesized

as given below. The structure of the synthesized compounds was confirmed on the basis of spectral and

elemental analysis.

The compound (1) 1-(2-(1H-benzo[d][1,2,3]triazol-1-yl) acetyl)pyrazolidine-3,5-dione is synthesized by

irradiating mixture of compound (II), diethyl malonate and 2-3 drops of glacial acetic acid. The IR

spectrum exhibited bands due to 1735, 1730, 1666 (C=O), and1H NMR gives shift at 4.75 (s, 2H, CH2),

3.35 (s, 2H, CH2 o) and molecular ion peak [M+] was found at 259 which confirmed the formation of

compound (1).

The compound (2) 1-(2-(1H-benzo[d][1,2,3]triazol-1-yl)acetyl)-2-acetylpyrazolidine-3,5-dione was

synthesized by irradiating mixture of compound (II), diethyl malonate and 5ml of glacial acetic acid. The

IR spectrum exhibited bands due to 1740,1693,1670,1640 (C=O),1H NMR gives shift at 4.60 (s, 2H,

CH2 ) , 3.30 (s, 2H, CH2), 2.40 (s, 3H, CH3) molecular ion peak [M+] was found at 301 which confirmed

the formation of compound (2).


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117 IJGHC; 2012, Vol.1, No.2, 108-119.

Table: 3. Antibacterial Activities of the synthesized compounds (1-8).

Antibacterial activity

Comp

ounds

E. coli P. aeruginosa B. subtitis S. aureus

50g

/ml

100g

/ml

200g

/ml

50g

/ml

100g

/ml

200g

/ml

50g

/ml

100g

/ml

200g

/ml

50g

/ml

100g

/ml

200g

/ml

1 _ ++ ++ _ + ++ _ ++ ++ _ _ +

2 _ ++ +++ _ _ + _ ++ +++ _ ++ +++

3 + ++ ++++ _ ++ ++ _ ++ +++ _ ++ ++

4 + +++ ++++ _ + ++ _ ++ ++++ _ ++ +++

5 _ + +++ _ + +++ _ ++ ++ _ ++ +++

6 _ ++ +++ _ + + _ ++ +++ _ _ +++

7 _ + +++ _ + +++ _ ++ +++ _ + +++

8 _ +++ ++++ + ++ +++ + ++ +++ _ + +++

Ciprofl

oxacin

++++ ++++ ++++ ++++ ++++ ++++ ++++ ++++ ++++ ++++ ++++ ++++

(-)< 6mm; (+) = 7 - 10 mm; (++) =11 15 mm; (+++) = 16 - 21mm; (++++) = 22 - 28mm.

The compound (3) 2-(1H-benzo[d][1,2,3]triazol-1-yl)-1-(3,5-dimethyl-4,5-dihydropyrazol-1-yl)ethanone

was synthesized by irradiating mixture of compound (II) and acetyl acetone. The IR spectrum exhibited

bands due to 1553(C=N) ,

1

H NMR (400 MHz, DMSO-d6) showed peaks due to 3.35(s, 3H, CH3), 2.40 (s,3H, CH3 ) ) and molecular ion peak [M

+] was found at 257 which confirmed the formation of compound

(3).

The compound (4) 1-(2-(1H-benzo[d][1,2,3]triazol-1-yl)acetyl)-3-(chloromethyl)-1H-pyrazol-5(4H)-one

was synthesized by microwave irradiation of mixture of compound (II) and 1- Chloro-hexane 2-4 dione.

The IR spectrum exhibited bands due to 1695, 1666 (C=O), 1606(C=N),1H NMR (400 MHz, DMSO-d6)

showed peaks due to 4.30 (s, 2H, CH2 ) , 3.22 (s, 2H, CH2) and molecular ion peak [M+] was found at

291; which confirmed formation of compound (4).

The compound (5) 1-(2-(1H-benzo[d][1,2,3]triazol-1-yl)acetyl)-3-methyl-1H-pyrazol-5(4H)-one was

synthesized by microwave irradiation of mixture of compound (II), hexane-2, 4-dione and acetic acid.

The IR spectrum exhibited bands due to 1680,1606(C=O),1530(C=N) and 1H NMR (400 MHz, DMSO-

d6) showed peaks due to 3.42 (s, 2H, CH2), 3.35 (s, 3H, CH3) and molecular ion peak [M+] was found at

257 which confirmed formation of compound (5).

The compound (6) 1-(2-(1H-benzo[d][1,2,3]triazol-1-yl)acetyl)-3-amino-1H-pyrazol-5(4H)-one was

synthesized by microwave irradiation of mixture of compound (II) and ethyl 2-cyanoacetate. The IR

spectrum exhibited bands due to 1698, 1672 (C=O), 1554(C=N) and NMR (400 MHz, DMSO-d6) showed

peaks due to 5.12 (s, 2H, NH2), 4.50 (s, 2H, CH2 ) , 3.42 (s, 2H, CH2) and molecular ion peak [M+] was

found at 258 which confirmed formation of compound (6).

The compound (7) 1-(2-(1H-benzo[d][1,2,3]triazol-1-yl)acetyl)-4-phenylthiosemicarbazide was

synthesized by microwave irradiation of mixture of compound (II) and phenyl isothiocynate in DMF .The IR spectrum exhibited bands due to 1100(C=S), NMR (400 MHz, DMSO-d6) showed peaks due to (s,


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118 IJGHC; 2012, Vol.1, No.2, 108-120.

2H, CH2), 2.20 (s, H, HN-N), and molecular ion peak [M+] was found at 326 which confirmed formation

of compound (7).

The compound (8) (E)-N-(4-oxo-2-(phenylimino) thiazolidin-3-yl)-1Hbenzo[d][1,2,3]triazole-1-

carboxamide was synthesized by irradiating mixture of compound (7) andethylchloroacetate in presence

of catalytic amount of morpholine. The IR spectrum exhibited bands due to1698, 1649(C=O), 740(S-C-S),

NMR (400 MHz, DMSO-d6) showed peaks due to 4.10 (s, 2H, CH2) and molecular ion peak [M+] was

found at 352 which confirmed formation of compound(8).

CONCLUSION

Most of the synthesized compounds were found to possess mild to moderate antibacterial and antifungal

activity except a couple of compounds which showed excellent activity, almost equivalent to the

compounds will take place which may lead to a potentially improved compounds.

ACKNOWLEDGEMENTS

The authors are thankful to Dr.Suman Jain, Director of shri ram college of Pharmacy, for providing

laboratory facilities authors are also thankful to Director, CDRI Lucknow, India for providing spectral and

analytical data. Special thanks to Dr. Ashok Kumar Sharma (A.D.) Regional Disease Diagnostic Center,

Kota (Rajasthan) for antimicrobial screening.

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*Correspondence Author: Kalmendra Singh Sisodiya; Department of Chemistry,

Pacific University, Udaipur, India.

Email:[email protected]

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