INTRODUCTION:

Pyrimidine is 6- member heterocyclic ring compound composed of nitrogen and carbon. They are present through nature in various forms and are the building blocks of numerous natural compounds from antibiotics to vitamins and liposaccharides . The most commonly recognized pyrimidine are the bases of RNA and DNA, the most abundant being cytosine, thymine or uracil. The origin of term pyrimidine dates back to 1884 when pinner coined the term from a combination of the words pyridine and amidine because of the structural similarity to these compounds. ^[1] Pyrimidine is important class of organic compounds, some of which shows significant activity such as anti-tumor, antimicrobial, cardiovascular agent. In addition 2-thiouracil has certain biological activity as antibacterial antifungal, antiprotozoal and antiviral activity.

Mononuclear and condensed pyrimidine exhibits a wide range of medicinal activity. The mononuclear pyrimidine are comparatively difficult to synthesizes and purify than condensed analogues. ^[2]

The reaction mechanism of biginelli reaction is a series of bimolecular reaction leading to the desired dihydropyrimidine. The beginelli synthesis is a condensation reaction of α,β ketoesters, aldehyde and thiorea in the presence of Lewis or mineral acids to yield pyrimidine pyrimidine.[3-5].

MATERIALS AND METHODS:

All the chemicals and solvent were procured from commercial source. The reagent was purchased from Research lab, sigma Aldrich, loba chemie pvt. Ltd., Himedia laboratories. Melting points of all synthesized compounds was determined by open capillary method and are uncorrected. Thin layer chromatography was used to assess the course of reaction and the purity of the intermediate and the final compounds were confirmed by applying a single spot on TLC plate silica gel G by using chloroform / methanol (9:1) used as mobile phase .TLC plates were visualized using iodine chamber the IR spectra were recorded using KBR disc on Jasco FTIR-410.

Experimental procedure [6, 7]:

Procedure for preparation of Compounds 1:

A mixture of thiourea (0.76 gm, 0.01 mol), ethyl cyanoacetate (1.13 gm, 1.07 ml, 0.01 mole) and aldehydes (0.01 mol), anhydrous potassium carbonate (o.o1 mol) in absolute ethanol (25 ml) was heated under reflux for 12 hr. The reaction mixture was allowed to cool and formed precipitate was filtered. The residue was triturate with water and neutralized with acetic acid. The precipitate was filtered, washed twice with water, dried and crystallize from ethanol to give compounds 1 6-(4-chlorophenyl)-4-oxo-2-thioxo-1, 2, 3, 4-tetrahydropyrimidine-5-carbonitrile. 1 M.p-258-260 oc , yield 84.31 % , molecular formula C13H6N30SCl ,molecular wt- 263.28. IR- 1340-1015 (C-N), 1440, 1606 (C=C aromatic), 1686 (C=O), 2231(CN) & 3300(N-H Sec).

Procedure for preparation of Compounds 2:

A mixture of 1 (0.01 mol) and phosphorus pentachloride (0.01 mol) in phosphorus oxychloride (20 ml) was heated on a steam bath for 4 hr and the reaction mixture poured gradually on to crashed ice. The precipitate was filtered off, dried then crystallized from the proper solvent to give compounds 2.

4-chloro-6-(4-chlorophenyl)-2-thioxo-1, 2dihydropyrimidine-5-carbonitrile .2

m.p- 138-144oc , yield 73.02 %, molecular formula C11H5N3S Cl2 , molecular wt- 281.73 .IR -1330-1076 (C-N) , 1476,1403 (C=C Ar), 1691(C=N), 2231(CN),3300 ( Sec N-H ).

Procedure for preparation of compound 2a:

A mixture of compound 2 (0.01 mol) and 4-bromoaniline (0.01 mol) in isopropyl alcohol (30ml) was refluxed for 18 hr. The reaction was monitored by TLC. The reaction mixture was then refrigerated overnight. The product obtained was filtered, dried.

4-(4-bromophenylamino)-6(4-chlorophenyl)-2-thioxo-1,2-dihyropyrimidine-5-carbonitrile (2a)

m.p- 308-310^oc , yield 30.52 %, molecular formula , C₁₇H₁₀N₄SBrCl molecular wt- 406 .IR -2242 (C-N) , 1488 (C=C Ar), 1507 (c-c Ar) , 796 (C-Cl), 1092 (C=S).

Procedure for preparation of compound 2b:

A mixture of compound 2 (0.01 mol) and 4-nitroaniline (0.01 mol) in isopropyl alcohol (30ml) was refluxed for 18 hr. The reaction was monitored by TLC. The reaction mixture was then refrigerated overnight. The product obtained was filtered, dried.

4-(4-Nitrophenylamino)-6(4-chlorophenyl)-2-thioxo-1, 2-dihyropyrimidine-5-carbonitrile

m.p- 308-310^oC , yield 24.63 %, molecular formula , C₁₇H₁₀N₅SCl molecular wt- 382.3 .IR -2210 (C-N) , 1494 (C=C Ar), 1541 (c-c Ar) , 750 (C-Cl), 1110 (C=S), 1500 (Ar-NO2)

Procedure for preparation of Compounds 2c:

A mixture of 2, (0.01 mol) and hydrazine hydrate (0.01 mol) in methanol (10 ml) was stirring for 17 hr. The precipitate was filtered off, dried then crystallized from the proper solvent to give compounds 2c,

4-hydrazino-6-(4-chlorophenyl)-2-thioxo-1, 2-dihydropyrimidine-5-carbonitril. (2c)

M. p.160-164 OC, yield 46.55 , Molecular formula C11H8N5Cl Molecular weight 277 .IR 1486-1592(C=C Ar) , 1092 (C=S) 587 (C-Cl), 2924 (C-H Ar) , 2250 (CN ). H1 NHR chemical shift in DMSO 7.1-7.7(4H,Ar-H), 11.8(1-H,NH, D2O Exchangeable)

Procedure for preparation of compound 2d:

A mixture of compound 2 (0.01 mol) and 2, 4-dinitroaniline (0.01 mol) in isopropyl alcohol (30ml) was refluxed for 18 hr. The reaction was monitored by TLC. The reaction mixture was then refrigerated overnight. The product obtained was filtered, dried.

4-(2-,4-dinitrophenylamino)-6-(4-chlorophenyl)-2-thioxo1,2dihydropyrimidine-5-carbonitrile.

(2d) m.p- 162-164^oc , yield 52.38%, molecular formula C₁₇H₉N₆O₄SCl, , molecular wt- 427 .IR -2242 (C-N) , 1475(C=C Ar), 1508 (c-c Ar) , 650 (C-Cl), 1127 (C=S), 1396 (Ar-NO2) ,1647(C=N)

Procedure for preparation of compound 2e:

Mixture of compound 2 (0.01 mol) ,and anthranillic acid (1.37 gm , 0.01 mole) was reflux in butanol (50ml) for 12 hr , cooled ,filtered , dried and recrystallized from DMF / water to gives compound 2e.

10-oxo-3-(4-chlorophenyl)-1-thioxo-2,10-dihydro-1-H-pyrimido-(6-1-b)-quanazoline-4-carbonitrile .

m.p- 242-246^oc , yield 14 %, molecular formula C₁₈H₉N₄OSCl, , molecular wt- 364 .IR -2211 (C-N) , 1475(C=C Ar), 1507 (c-c Ar) , 797 (C-Cl), 1065 (C=S), 1652(C=N)

Anti- inflammatory screening:

In vivo anti-inflammatory activity study:

Animal used: Albino Wistar rats.

Method Used: Carrageenan-induced paw edema model.

Weight of rat – 183- 250 gm

Standard drug used – Dicleofenac sodium.

Dose of drug- 50 mg/kg

Procedure

1) Weight the animals and number them.

2) Make a mark on the hind paws just beyond tibio-tarsal junction, so that every time the paw is dipped in mercury column up to the fixed mark to ensure constant paw volume.

3) Note the initial paw volume of each rat by mercury displacement method.

4) Divide animal in to three groups (to 1^st gr. Inject standard drug, to 2^nd gr. Inject test compound and to 3^rd gr inject control i.e. 1% DMSO) each gr contain 6 animals.

5) After 30 min inject 0.1 ml of 1% carragenan in sub plantar region.

6) Note the paw volume of rat at 1hr, 2hr, 3hr, and 4hr after carragenan challenge using plethysmometer.

Following formula used to determine the % inhibition of paw edema of rat.

Observations of anti-inflammatory activity

Table no: 1: Observations of anti-inflammatory activity

Sr. no.	Compounds	0 Hrs	1Hrs	2Hrs	3Hrs	4Hrs	% inhibition of paw edema of rat. ( %)
1	2a	0.3 ±0.02	0.36±0.02	0.45±0.03	0.61±0.04	0.65±0.05	35
2	2b	0.3±0.01	0.45±0.02	0.51±0.01	0.62±0.02	0.64±0.02	43.33
3	2c	0.23±0.02	0.31±0.03	0.42±0.03	0.56±0.03	0.64±0.01	31.66
4	2d	0.36±0.01	0.47±0.02	0.50±0.05	0.52±0.01	0.54±0.01	70
5	2e	0.36±0.01	0.52±0.01	0.62±0.02	0.72±0.02	0.76±0.01	33.33
6	Control 1% carrageen	0.27±0.03	0.43±0.03	0.58±0.02	0.72±0.03	0.87±0.01	-
7	Standard	0.23±0.02	0.34±0.03	0.28±0.01	0.25±0.01	0.27±0.02	93.33

1) Anti-inflammatory activity

Figure no 1 : Graph of Anti-inflammatory activity of compound 2a-2e

RESULT AND DISCUSSION:

Dicleofenac sodium was used as standard for measurement of anti-inflammatory activity of 1, 2-disubstituted pyrimidine derivatives. In this method the % inhibition of edema of rat paw recorded as response latency.

Compound no. 2d showed significant reduced in paw volume of rat. These compounds exhibit good anti-inflammatory activity in comparison of all compounds.

REFERENCE:

1. Brown D.J Katrizsky, A.R .Rees, C.W. Boulton, (1984), A comprehensive heterocyclic chemistry; 3; 57-155.

2. Phaujdar, M.S.Kathravan, M. K. Briwal, J.B. Shah, A.K. Jain k.s . (2008), tet leet, 49,1269.

3. Wikipedia.com.

4. C.Oliver Kappe; (2005), The Biginelli Reaction, ISBN-978-3-527-30806-4.

5. Folkers.k; Fissekis, (1933), J.D.J Am chem., 55, 3784-3791.

6. Mosaad sayed Mohamed. et al, (2011), synthesis and antimicrobial evolution of some 6-aryl-5-cyano-2-thiouracil derivatives, 171-185.

7. O.A.Fathalla, (2009), Synthesis, antibacterial and anticancer evolution of some pyrimidine derivatives, 127-132.

8. Rama Krishna Kota, Synthesis and anti-inflammatory activity of novel pyrazolo [3, 4-d] pyrimidine, J. Chem. Pharm. Res., 2011, 3(4): 848-853.

Received on 14.07.2015 Modified on 21.07.2015

Asian J. Research Chem. 8(8): August 2015; Page 507-510

DOI: 10.5958/0974-4150.2015.00080.2