INTRODUCTION:

Indoles are found to be an important class of heterocycles and biologically active compounds such as pharmaceuticals, agrochemicals and alkaloids. Indole derivatives have therefore, captured wide attention of organic synthetic chemists. Medicine and biochemistry are also interested in many aspects of the indole chemistry. Acute, chronic inflammation and different type of arthritis are the inflammatory disorders which are a big blow to humanity and continual search for newer non-steroidal anti-inflammatory agents is the only way to fortify against this awful threat. The discovery of indomethacin¹ as a successful agent for clinical treatment of anti-inflammatory disorders has led to the exploration of indole moiety to obtain better anti-inflammatory agents. Furthermore indole and its analogs possess wide spectrum of biological activities, such as anti-inflammatory^2-4,anti-microbial⁵, anti-bacterial⁶, anticonvulsant^7-8 and cardiovascular⁹. Indole is a popular component of fragrances and the precursors of many pharmaceuticals.

Indazoles constitute an important class of heterocycles that display interesting biological properties¹⁰, such as anti-depressant¹¹, anti-inflammatory¹², analgesic, antipyretic¹³, dopamine antagonistic¹⁴, anti-tumor¹⁵, anti-emetic¹⁶, and anti-HIV activities¹⁷. The indazole ring system is also present in many other compounds such as herbicides, dyes and sweeteners.

In view of the importance of the Indole and Indazoles we undertook the synthesis of these title compounds.

MATERIALS AND METHODS:

The ¹H NMR and ¹³C spectra were recorded in the indicated solvent (CDCl₃ ) on a Varian 500 MHz and 200 MHz spectrometer with TMS as internal standard. All chemical shifts (δ) were reported in ppm. The Mass spectra were measured on a GC/MS-QP1000EX (EI, 70 eV) mass spectrometer. Infrared spectra were recorded in KBr on Schimadzu 470 spectrophotometer. The progress of the reaction was monitored by TLC silica gel.

Table.1

Compound	R
3a	6-Bromo
3b	7-Bromo

Table.2

Compound	R²	R¹
4a	Methyl	H
4b	Methyl	Cl
4c	Methyl	Br
4d	Phenyl	H
4e	Phenyl	Cl

Table.3

Compound	R	R²	R¹
5a	6-Bromo	1-methyl	1H
5b	7-Bromo	1-methyl	1H
5c	6-Bromo	1-phenyl	1H
5d	7-Bromo	1-phenyl	1H
5e	6-Bromo	1-methyl	3-chloro
5f	7-Bromo	1-methyl	3-chloro
5g	6-Bromo	1-phenyl	3-chloro
5h	7-Bromo	1-phenyl	3-chloro
5i	6-Bromo	1-methyl	3-Bromo
5j	7-Bromo	1-methyl	3-Bromo

Bromo-1-(prop-2-ynyl)-1H-indazoles (3a-b)

To a stirred solution of bromo-1H-indole (1 mmole) in DCM (20 ml), proporgyl bromide (2.5 m mole) and Di isopropyl ethylamine (2 m mole) were added and refluxed for 4-5 h at 60^oC. The solvent was evaporated in vacuum and added water. The product was extracted from DCM and washed with brine solution and dried.

6-Bromo-1-(prop-2-ynyl)-1H-indazole (3a)

¹HNMR (400MHz, CDCl₃): δ, ppm 8.03 (s, 1H), 7.50 (d, 1H, J=7.8Hz), 7.34 (d, 1H, J=7.8Hz, aromatic), 7.30 (t, 1H, aromatic), 5.18 (d, 1H, yne, J = 2.4 Hz), 2.42 (t,yne 1H)

¹³C NMR (100 MHz, CDCl₃): δ, ppm 139, 133, 127, 125, 123, 114, 108, 76, 74, 39.

MS: m/z=236 (M⁺¹)

7-Bromo-1-(prop-2-ynyl)-1H-indazole (3b)

¹HNMR (400MHz CDCl₃): δ, ppm 8.05 (s, 1H), 7.55 (d, 1H, J=7.8Hz), 7.45 (d, 1H, J=7.8Hz), 7.35 (t, 1H), 5.21 (d, 1H, J = 2.4 Hz), 2.45 (t, 1H)

¹³C NMR (100 MHz, CDCl₃): δ, ppm 140, 133, 127, 126, 124, 115, 109, 77, 75, 40.

MS: m/z=236 (M⁺¹)

Substituted-1-((1-tosyl/methylsulphonyl-1H-indol-2-yl) methyl)-1H-indazoles (5a-j)

To a solution of compound 3a (1 m mole) in DCM (50 ml), compound 4a (1.2 m mole) was added, stir the contents at RT for 2hrs, solvent was removed by distillation, crude product was taken in toluene (40 ml) and DMSO (20 ml) was added and refluxed for about 10h at 80^oC.After the completion of reaction, it was quenched with 1% HCl and extracted with DCM, dried and concentrated to obtained product.

6-Bromo-1-((1-methylsulphonyl-1H-indol-2-yl) methyl)-1H-indazole (5a)

¹HNMR (400MHz CDCl₃): δ, ppm 8.11(s,1H), 7.97 (d,1H), 7.45 (m,2H), 7.35 (m, 2H), 7.28 (m, 2H), 6.23 (s, 1H), 5.89 (s, 2H), 2.92 (s, 3H)

¹³C NMR (100 MHz, CDCl₃): δ, ppm 140, 136, 134, 134, 128, 127, 125, 125, 124, 123, 121, 114, 113, 113, 111, 108, 47, 40. MS: m/z=406 (M⁺¹)

7-Bromo-1-((1-methylsulphonyl-1H-indol-2-yl)methyl)-1H-indazole (5b)

¹HNMR (400MHz CDCl₃): δ, ppm 8.09 (s, 1H), 7.95 (d, 1H), 7.55 (m, 2H), 7.42 (m, 2H), 7.31 (m, 2H), 6.25 (s, 1H), 5.91 (s, 2H), 2.96 (s, 3H)

¹³C NMR (100 MHz, CDCl₃): δ, ppm 141, 137, 135, 134, 129, 128, 125, 125, 124, 124, 121, 114, 113, 111, 109, 47, 40.

Mass: m/z=406 (M⁺¹)

6-Bromo-1-((1-tosyl-1H-indol-2-yl)methyl)-1H-indazole (5c)

¹HNMR (400MHz CDCl₃): δ, ppm 8.21 (s, 1H), 8.08 (d, 1H), 7.45 (m, 2H), 7.30 (m, 2H), 7.28 (m, 4H), 7.24 (m, 2H), 6.21 (s, 1H), 5.79 (s, 2H), 2.31 (s, 3H)

¹³C NMR (100 MHz, CDCl₃): δ, ppm 141, 137, 135, 134,128, 128, 127, 127, 125, 125, 124, 124, 123, 123, 121 114, 113, 111, 47, 29.

MS: m/z=481 (M⁺¹)

7-Bromo-1-((1-tosyl-1H-indol-2-yl)methyl)-1H-indazole (5d)

¹HNMR (400MHz CDCl₃): δ, ppm 8.20 (s, 1H), 8.10 (d, 1H), 7.50 (m, 2H), 7.34 (m, 2H), 7.30 (m, 4H), 7.28 (m, 4H), 6.19 (s, 1H), 5.80 (s, 2H), 2.32 (s, 3H)

¹³C NMR (100 MHz, CDCl₃): δ, ppm 141,137, 135, 134, 128, 128, 127, 127, 125, 124, 124, 123, 123, 121, 114, 113, 111, 47, 30

MS: m/z=481 (M⁺¹)

6-Bromo-1-((3-chloro-1-methylsulphonyl-1H-indol-2-yl)methyl)-1H-indazole (5e)

¹HNMR (400MHz CDCl₃): δ, ppm 3.44 (s, 3H), 6.07 (s, 2H), 6.40 (s, 1H), 7.22 (t, 1H), 7.27 (d, 1H), 7.44 (dd, 1H), 7.67 (d, 1H), 7.73 (s, 1H), 7.90 (d, 1H), 8.60 (s, 1H)

¹³C NMR (100 MHz, CDCl₃): δ, ppm 148, 137, 137, 135, 130, 128, 127, 126, 125, 124, 123, 121, 117, 115, 112, 110, 50, 41.

MS: m/z=440 (M⁺¹)

7-Bromo-1-((3-chloro-1-methylsulphonyl-1H-indol-2-yl)methyl)-1H-indazole (5f)

¹HNMR (400MHz CDCl₃): δ, ppm 8.63 (s, 1H), 7.92 (d, 1H), 7.74 (s, 1H), 7.68 (d, 1H), 7.45 (dd, 1H), 7.29 (d, 1H), 7.25 (t, 1H), 6.43 (s, 1H), 6.09 (s, 2H), 3.44 (s, 3H)

¹³C NMR (100 MHz, CDCl₃): δ, ppm 149, 138, 136, 130, 128, 127, 126, 125, 124, 123, 122, 118, 115, 113, 110, 51, 41

MS: m/z=440 (M⁺¹)

6-Bromo-1-((3-chloro-1-tosyl-1H-indol-2-yl)methyl)-1H-indazole (5g)

¹HNMR (400MHz CDCl₃): δ, ppm 8.67 (s, 1H), 7.93 (d, 1H), 7.78 (s, 2H), 7.70 (d, 1H), 7.62 (d, 2H), 7.46 (dd, 1H), 7.29 (d, 1H), 7.25 (t, 1H), 7.09 (d, 2H), 6.45 (s, 1H),6.10 (s, 2H), 2.35 (s, 3H)

¹³C NMR (100 MHz, CDCl₃): δ, ppm 150, 139, 136, 130, 129, 128, 127, 126, 125, 125, 124, 123, 122, 118, 115, 113, 110, 51, 26

MS: m/z=515 (M⁺¹)

7-Bromo-1-((3-chloro-1-tosyl-1H-indol-2-yl)methyl)-1H-indazole (5h)

¹HNMR (400MHz CDCl₃): δ, ppm 8.68 (s, 1H), 7.95 (d, 1H), 7.72 (s, 2H), 7.71 (d, 1H), 7.64 (d, 2H), 7.45 (dd, 1H), 7.30 (d, 1H), 7.26 (t, 1H), 7.10 (d, 2H), 6.46 (s, 1H), 6.08 (s, 2H), 2.36 (s, 3H) ¹³C NMR (100 MHz, CDCl₃): δ, ppm 149, 140, 136, 130, 129, 128, 127, 126, 125, 125, 124, 123, 122, 118, 115, 113, 110, 51, 26

MS: m/z=515 (M⁺¹)

6-Bromo-1-((3-bromo-1-methylsulphonyl-1H-indol-2-yl) methyl)-1H-indazole (5i)

¹HNMR (400MHz CDCl₃): δ, ppm 8.60 (s, 1H), 7.91 (d, 1H), 7.72 (s, 2H), 7.69 (d, 1H), 7.45 (dd, 1H), 7.30 (d, 1H), 7.26 (t, 1H), 6.42 (s, 1H), 6.42 (s, 1H), 6.10 (s, 2H), 3.43 (s, 3H)

¹³C NMR (100 MHz, CDCl₃): δ, ppm 150, 139, 136, 130, 128, 127, 126, 125, 124, 123, 122, 118,115, 113, 110, 51, 42

MS: m/z=484 (M⁺¹)

7-Bromo-1-((3-bromo-1-methylsulphonyl-1H-indol-2-yl)methyl)-1H-indazole (5j)

¹HNMR (400MHz CDCl₃): δ, ppm 8.63 (s, 1H), 7.92 (d, 1H), 7.73 (s, 1H), 7.70 (d, 1H), 7.46 (dd, 1H), 7.30 (d, 1H), 7.25 (t, 1H), 6.41 (s, 1H), 6.08 (s, 2H), 3.45 (s, 3H)

¹³C NMR (100 MHz, CDCl₃): δ, ppm 149, 140, 136, 130, 128, 127, 126, 125, 125, 124, 122, 118, 115, 113, 111, 51, 41

MS: m/z=484 (M⁺¹)

Anti bacterial activity

Bacterial Cultures

Strains of Bacillus subtilis MTCC 441, Bacillus cereus ATCC 9372, Staphylococcus aureus ATCC 96, E.Coli ATCC 8739, Klebsielia pneumonia MTCC 109, Salmonella typhi ATCC 4420 were taken from department of microbiology, Kakatiya University Warangal. The bacterial cultures were developed by selective nutrient broth at 37oC and stored at 4^oCfor further use.

Preparation of standard bacterial suspensions

Initially, all the bacterial strains were inoculated on to enriched nutritive broth media and

Incubated at 35± 2^oC for 24 h 25%of turbidity at 580nm was taken in to consideration for antibacterial assay. Spectrophotometrically using Bausch and Lomb spectrophotometer comparable to McFarland turbidity standard. This level of turbidity is equivalent to approximately 3.0 × 108 CFU/ml (a stock standard from which a working standard was drawn with concentration of 1 × 108 CFU/ml). The antibacterial activity of these extracts was carried out according to the method described by Raman with slight modifications¹⁸. Each selective medium was inoculated with the test organism suspended in nutritive broth. Once the agar was solidified, it was punched with a six millimeters diameter wells and filled with 25 μL of the title compounds of various concentrations and corresponding wells with positive and negative control. The concentration of the methanolic extracts employed at concentrations 25, 50, 75 μg/ml simultaneously, gentamycin sulfate (10 μg/ml) is used as positive control.

The test was carried out in triplicate. The plates were incubated at 35 ±2°C for 24 h. The inhibition zone diameter was measured in mm.

RESULTS:

Antibacterial activity

Compounds which were synthesized, posses antibacterial activity. Among the compounds tested(5a-5j) 5g showed prominent antibacterial activity compared with that from other compound 5g noticed highest zone of inhibition 16mm against gram negative strain protius vulgaris where as other compounds are also showed significant zone of inhibitions against protius vulgaris (table ) according to the data obtained in the current study it has been understood that compounds from (5e-5j) are more effective than the compounds from (5a-5d).this might because of chloro group substituted additionally at 3^rd position of the ring. However some of the compounds have same functional group are also showed good activity. All the gram negative strains are more susceptible against tested compounds.

The zone of inhibition were represented in mm

Table.4

Microorganism	5a	5b	5c	5d	5e	5f	5g	5h	5i	5j	Gentamycin
*gram-positive*
Bacillussubtitis	4	2	5	4	8	11	9	8	7	9	19
Bacilluscereus	6	7	3	2	12	10	11	7	8	7	14
s.aureus	3	5	8	5	7	8	11	10	7	6	16
*Gram-negative*
E.coli	7	2	7	5	8	9	11	13	10	7	13
Protevs vulgaris	5	1	4	3	12	14	16	11	8	10	20
k. pneumonia	3	4	6	4	9	6	11	7	7	9	15

RESULTS AND DISCUSSION:

Current investigation is devoted towards the research and development of highly efficient heterocyclic molecules with biologically active. Our Efforts was mainly focused on the synthesis ofSubstituted-1-((1-tosyl/methylsulphonyl-1H-indol-2-yl) methyl)-1H-indazoles from compound (2) by using Grubbs first generation catalyst. All the synthesized compounds were characterized by elemental analysis, ¹HNMR, 13CNMR and Mass spectral data.

CONCLUSION:

The present study reports an efficient synthesis of title compounds in good yields and moderate to potent antibacterial activities.

ACKNOWLEDGEMENT:

We sincerely thank the Head Department of Chemistry, Kakatiya University for his support and encouragement

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Received on 10.03.2014 Modified on 30.03.2014

Asian J. Research Chem. 7(5): May 2014; Page 509-512