Synthesis, Characterization of 3-Chloro 4-(4- Substituted Phenyl -1- (4- Nitro Phenylazetidin -2-one by Microwave Method and Evaluation of Their Antibacterial Activity

Y. Pradeep Kumar¹*, S. Chand Basha¹, K. Anusha², K. Madhuri², C. Gopinath³

¹Asst. Professor, Dept. of Pharmaceutical Chemistry, Annamacharya College of Pharmacy, New Boyanapalli, Rajampet, Kadapa (Dist) A.P, 516115.

²Dept. of Pharmaceutical Chemistry, Annamacharya College of Pharmacy, New Boyanapalli, Rajampet, Kadapa (Dist) A.P, 516115.

³HOD, Dept. of Pharmaceutical Chemistry, Annamacharya College of Pharmacy, New Boyanapalli, Rajampet, Kadapa (Dist) A.P, 516115.

*Corresponding Author E-mail: y.pradeepkumar36@gmail.com

ABSTRACT:

Non classical, High-speed, environmentally benign synthesis with microwaves has attracted researchers for organic synthesis was a considerable amount of attention in recent years. An expeditious one pot microwave irradiation method for preparation of 2- azetidinones is developed. This method has been assessed as greener methodology. In our present study, A series of six novel 2-azetidinones were synthesized, compounds were identified by melting point and thin layer chromatography , functional groups of synthesized compounds were confirmed by IR spectroscopy, compounds were evaluated for their antimicrobial activities. The activities were due to cyclic carbonyl group in 2-azetidinones. Some of the compounds have shown comparative antimicrobial activities against all the microbial strains.

KEYWORDS: Microwave synthesis, 2-Azetedinone, Anti bacterial activity.

INTRODUCTION:

2-Azetidines have been extensively investigated by the organic chemists due to their close association with various types of biological activities It is a four-membered cyclic lactam (ß-lactam) skeleton has been recognized as a useful building block for the synthesis of large number of organic molecules by exploiting the strain energy associated with it. The Staudinger reaction ([2+2] ketene-imine cycloaddition reaction) is regarded as one of the most fundamental and versatile methods for the synthesis of structurally diverse 2-azetidinone derivatives. Azetidine-2-ones also have great importance because of the use of ß -lactam derivatives as antibacterial agents recently, some other types of biological activity beside the antibacterial activity have been reported in compounds containing 2- azetidinone ring.

Efforts have been made in exploring such new aspects of β-lactam chemistry versatile intermediates for their synthesis of aromatic β- amino acid and their derivatives, peptides, polyamines, polyamino alcohols, amino sugars and polyamino ethers. The cyclic 2-azetidinone skeleton has been extensively used as a template to build the heterocyclic structure fused to the four membered rings. The β-lactam heterocycles are still the most prescribed antibiotics used in medicine. They are considered as an important contribution of science to humanity¹

The biological activity of β lactam antibiotics such as penicillins and cephalosporins are attributed to the presence of 2-azetidinone ring in them ². Compounds carrying azetidin-2- one ring are reported to exhibit certain biological activities likeantagonists³, hypoglycemic ⁴, anti-inflammatory ⁵, Antitubercular⁶, anaesthetic⁷, analgesic ⁸, antimalarial ⁹, antidepressant ¹⁰ and enzyme inhibition activity¹¹

Cycloaddition of monochloroacetylchloride with imine (schiff base) result in formation of 2-azetidinone (β-lactam).The reaction involves direct acylation of imine with monochloroacetylchloride. The reaction is carried out with base as triethylamine gives β- lactam ¹².

EQUIPMENTS:

Melting points were taken in digital melting point apparatus. The microwave assisted synthesis of 2-azetidinone derivatives were carried out in IFB 17 PG2S, 2450MHz, 90° C , Infrared spectra of the prepared compounds were recorded in KBr disc method on Shimadzu IR 8000 series spectrometer All the synthesized compounds are purified by recrystallization. The reactions were followed up and purity of compounds was monitored on pre- coated TLC plates using different solvent system and visualizing the spots in iodine chamber.

MATERIALS:

All the chemicals and solvents were obtained from E-Merck and S.D. Fine India (AR grade) and were used without further purification.

METHODOLOGY:

Microwave-enhanced chemistry is based on the efficient heating of materials by “microwave dielectric heating” effects. This phenomenon is dependent on the ability of a specific material (solvent or reagent) to absorb microwave energy and convert it into heat¹³. Microwave irradiation has gained popularity in the past decade as a powerful tool for rapid and efficient synthesis of a variety of compounds because of selective absorption of microwave energy by polar molecules. The application of Microwave irradiation to provide enhanced reaction rate and improved product field in chemical synthesis and it is providing quite successful in the formation of a variety of carbon- heteroatom bonds ¹⁴. Many researchers have described accelerated reaction rates, with a large number of papers that have appeared proving the synthetic utility of MORE chemistry in day to day organic synthesis. It can be termed as ‘e- chemistry’ because it is easy, effective, economical, and eco-friendly, and is believed to be a step toward achieving green chemistry objectives¹⁵. Within the framework of ‘Green Chemistry’ we have now developed an environmentally benign and novel approach for the synthesis of azetidine-2-ones.

Scheme: Figure: 1

General method for the preparation of compounds IIa-IIf:

P- nitro aniline 0.01mol (1.2 gms)was dissolved in 30 ml of ethanol containing few drops of glacial acetic acid .The appropriate aromatic aldehyde (0.01 mol) was added to the reaction mixture. It was heated in microwave for 90 seconds cooled and then poured into crushed ice .The solid obtained was filtered, washed with water and re crystallized with ethanol. Different aldehydes are shown in Table No.1

Mobile phase for TLC Benzene: Ethanol (7:3)

General method for the preparation of final compounds IIIa-IIIf:

To a stirred solution of step II products of P-nitro aniline (0.01 mol) ,tryethylamine (0.02 mol) in dioxan (dry 50ml) and monochloro acetyl chloride (0.02mol) was added drop wise at room temperature .The reaction mixture was stirred for 30 min and heated in micro wave for 60 seconds .A solid was obtained on removal of dioxan which was re crystallized from a mixture of ethanol and water. Functional groups of synthesized compounds were confirmed by performing IR spectroscopy, results were shown in Table No.3

Physical properties of synthesized compounds were shown in Table No.2

Mobile phase for TLC Chloroform: ethanol (8:2)

Figure: 1

SCHEME:

Table No 1: Different aromatic aldehydes used for the preparation of Schiff’s bases

Where R is

S.NO	COMPOUND	STRUCTURE
1.	Benzaldehyde
2.	p-Hydroxy benzaldehyde
3.	P-Chloro benzaldehyde
4.	P-Dimethyl benzaldehde
5.	3,4-Dimethoxybenzaldehyde
6.	p-Cyanobenzaldehyde

Table No 2: Physical properties of synthesized compounds

S.No	Compound code	% yield	Molecular formula	Molecular weight	Melting point	solubility	Rf value
1.	IIIa	72	C₁₅H₉O₃N₂Cl	299.5	188°C	Ethanol, Ethyl acetate, DMF, DMS	0.72
2.	IIIb	71	C₁₅H₉O₄N₂Cl	315.5	184°C	Ethanol, Ethyl acetate, DMF, DMS	0.68
3.	IIIc	70	C₁₅H₈O₃N₂Cl₂	333	194°C	Ethanol, Ethyl acetate, DMF, DMS	0.75
4.	IIId	65	C₁₇H₁₄O₃N₂Cl	342.5	186°C	Ethanol, Ethyl acetate, DMF, DMS	0.77
5.	IIIe	70	C₁₇H₁₄O₅N₂Cl	360.5	173°C	Ethanol, Ethyl acetate, DMF, DMS	0.70
6.	IIIf	62	C₁₆H₈O₃N₃Cl	324.5	182°C	Ethanol, Ethyl acetate, DMF, DMS	0.65

Table No 3: IR spectral values of synthesized compounds both Intermediates and final compounds.

S.no	Intermediate structure	IR Values	Final structure	IR Values
1.		(ArNo₂)15976, (ArCHstr)2943.3, (CN)14061, (NH-str)3277.06.		(Ar-No₂)1597.06, (Ar-CHstr)2943.3, (C=O) 1685.7, (C-Cl)852.59, (C-N)1406.1, (NH -str)3277.06.
2.		(ArNo₂)155806, (ArCHstr)2933.52, (CN)1471.1, (NH-str)3323.06.		(Ar-No₂) 1570.06, Ar-CH str)2941.44, , (C=O)1685.7, (C-Cl)852.59, (C-N)1406.1, (NH -str)3277.06
3.		(ArNo₂)1568 (ArCHstr)2958.80, (C-N)1406.1, (NH -str)3363.06.		(Ar-No₂) 1566, Ar-CH str) 2941.44, , (C=O)1685.7, (C-Cl)852.54, (C-N)1406.1, (NH -str)3277.06.
4.		(ArNo₂)1597 (Ar-CHstr)2941.44, (C-N)1406.1, (NH -str)3280.92.		(Ar-No₂) 1597, Ar-CH str) 2941.44, (C=O)1624.7, (C-Cl)852.54, (C-N)1406.1, (NH -str)3280.92.
5.		(ArNo₂)1570.06 (Ar-CHstr)2870.0, (C-N)1477.47, (NH -str)3254.2		(Ar-No₂) 1597, Ar-CH str) 2941.44, (C=O)1624.7, (C-Cl)852.54, (C-N)1406.1, (NH -str)3280.92.
6.		(ArNo₂)1570.06, (Ar-CHstr)2870.06, (CN)1477.47, (NH -str)3254.2, ( Arnitrile)2012.36		(Ar-No₂) 1597, Ar-CH str) 2941.44, (C=O)1624.7, (C-Cl)852.54, (C-N)1406.1, (NH -str)3280.92, ( Ar nitrile ) 2012.36

ANTIMICROBIAL ACTIVITY:

The in-vivo Antimicrobial activity was performed by Agar diffusion method. The new compounds were evaluated for in vitro anti bacterial activity against Gram-positive bacteria like Streptococcus aureus,. Bacillus subtilis, and Gram Negative bacteria like Vibrio cholerae, Pseudomonas aeruginosa, Agar nutrient broth was employed for bacterial growth.

From the microbial study it can be concluded that compounds bearing chloro, cyano, hyfroxy groups are more potent than remaining substituted compounds against Gram (+) and Gram (-) bacterias. All the synthesized compounds have structure activity relationship (SAR) because activity of compounds varies with substitution. On the basis of SAR it can be concluded that activity of compounds depends on electron withdrawing nature of substituted group. The sequence of the activity is as follow;

Cyano>Chloro>Hydroxy>N-Dimethylamino>3,4 Dimethoxy>Hydrogen

RESULT AND DISCUSSION:

A new method for the synthesis of various above azetidin-2-one derivatives using microwave irradiation offers significant improvements over existing procedures and thus helps facile entry into a synthesis of variety of azetidin-2-one derivatives. Also, this simple and reproducible technique affords various azetidin-2-one derivatives with short reaction times, excellent yields, and without formation of undesirable side products. The yields of different synthesized compounds were found to be in the range of 60-80% and the characterization was done by melting point, thin layer which confirm the completion of reaction. Functional groups were identified by performing IR spectroscopy , All the tested compounds showed good, moderate and poor biological activity.

CONCLUSION:

A new method for the synthesis of various above azetidin-2-one derivatives using microwave irradiation offers significant improvements over existing procedures and thus helps facile entry into a synthesis of variety of azetidin- 2-one derivatives. Also, this simple and reproducible technique affords various azetidin-2-one derivatives with short reaction times, excellent yields, and without formation of undesirable side products. The yields of different synthesized compounds were found to be in the range of 60-80% and the characterization was done by melting point . Characteristic IR bands show several functional vibration modes which confirm the completion of reaction. At present six derivatives were prepared and identified screened for antibacterial activity, In future we may fuse few more aldehydes to the p-nitro aniline and tested for their anti tubercular activity.

ACKNOWLEDGMENT:

I thankful to the Secretary C. Gangi Reddy Garu, Annamacharya Educational Trust, Principal Dr. C. Gopinath, Annamacharaya College of Pharmacy, Rajampet, Kadapa dist. for providing necessary facilities to carry out this research work and I much thank full to my beloved students who did this project very successfully.

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