Synthesis and biologically important of 2-mercaptobenthiazole (MBT)-clubbed Chalcone derivatives

. In this present work base catalyzed method used for formation of Chalcone of(E)-4-(3-(4-hydroxyphenyl)acryloyl)-5-methyl-2( p -tolyl)-1H-pyrazol-3(2H)-one ( II ) reacted with derivatives of

There are numerous biologically active bicyclic molecules containing two hetero atoms. 2-Mercaptobenzothiazole (MBT) is an important scaffold known to be associated with several biological activities, and its derivatives are manufactured worldwide for a wide variety of applications S-acethydrazide hydrazine [20], S-acyl [21]. MBT and their derivatives have attracted much attention of chemists and pharmacologists because of their broad spectrum of biological activities and applications as antifungal and antibacterial activities [22], fungicide, insecticide, sensitizer, and anti-scorching agent [23].

ILCPA Volume 63
Step-3 Synthesis of titled compounds (III a-f ) Scheme-1 Synthesis of compounds of (III a-f )

RESULT AND DISCUSSION
The synthetic route of the compounds is outlined in scheme-1. A series of titled compounds (III a-f ) were synthesized in three steps. Derivatives of S-benzo[d]thiol-2yl-2-chloroethanethioate (I af ) was prepared by reaction between different benzothiazole-2-thiol (where, initially prepare by different 2-amino benthiozole and carbon di-sulphide with KOH in EtOH) with chloro acetyl chloride and K 2 CO 3 IN DMF. Synthesis of(E)-4-(3-(4-hydroxyphenyl) acryloyl)-5-methyl-2(ptolyl)-1H-pyrazol-3(2H)-one (II) were prepared by reacting 1H pyrazole containing acetaphenone with p-hydroxybenzaldehyde where NaOH was used as a base catalyst. This product (II) on reaction with the derivatives of (I a-f ) resulted in the formation of titled compounds (III a-f ) in good yield.

IR spectra
The IR spectra of the titled compound (III a-f ) (molecular formula C 29 H 23 N 3 O 5 S 2 ) has given a weak absorption stretching vibration band observed at 2753 cm -1 confirmed the presence of methylene group in the final product. A sharp intensified band at 1647 cm -1 proves the presence of carbonyl group in the structure. The presence of (-C=C-) in the aromatic ring was proved by absorbance at 1537 cm -1 . The carbonyl functional group present in vicinity to the Chalcone (-CH=CH-) has shown a sharp and intense absorption peak at 1669 cm -1 . Another stretching vibration at 1591cm -1 in the spectra of compounds (III a-f ).

MATERIAL AND METHOD
Melting points were determined in open capillary tubes and were uncorrected. The IR spectra were recorded by a perkin-Elmer 237 spectrophotometer and 1H NMR was recorded in DMSO with TMS as internal standard on Bruker. AM 400. Mass spectra were recorded on M S route JMS 600-H. All the synthesized compounds were purified by recrystalization method. All the chemicals and solvents were A.R Grade and were used without further purification.

GENERAL PROCEDURE
Preparation of benzothiazole-2-thiol Substituted 2-amino thiophenol (0.01mol) was taken in R.B.F containing ethanol (40ml) and KOH (0.01mol), CS 2 (0.02mol) was added to the well-stirred solution and reflux for 12-15h.The ethanol was then distilled off and cooled to room temp. The content was poured into ice coldwater and acidifies with dilute HCL till the precipitates were obtained. The separated solid was washed with cold water and dried to get desired product. The formation of titled intermediate was confirmed by the TLC.

CONCLUSION
In the present work, all the titled compounds were synthesized by condensation of Chalcone with derivatives of 2-marcaptobenzthiazole. All the synthesized compounds were studied for antimicrobial activity. Compound 3c and 3e shows good activity. All the synthesized compounds were characterized by spectral data.