Reaction  2-R 5-oxo 5-H 6-Ethylcarboxylate 7-Phenyl -1 ,3,4-Thiadiazolo- [3,2-a] Pyrimidine  with Amin

Introduction

Condensed derivatives of 1,3,4-thiadiazolo[3,2- a]pyrimidinewere reported to possess a broadspectrum of biological activity^1-4, including antibacterial,antitumor, fungicidal, and herbicidal properties. However,thiadiazoles and their condensed analogs are still insufficientlystudied. In continuation of the search for substancespossessing increased ability to permeate through biologicalmembranes of various infectious species ^{5 – 7} and, in particular,for the new antibacterial drugs in these homologousseries of compounds.introduction of a substituent at position 6 of the.The introduction of a substituent at position 6 of the1,3,4-thiadiazolo [3,2-a] pyrimidine system efficientlyenhances the physiological activity of the oleculef^8-10.This replacement occurs in the reactions of 1,3,4 -thiadiazolo [3,2-a] pyrimidine derivatives withelectrophiles^11-13. In the present work, we studied the possibilities of thesynthesis of various derivatives of 1,3,4-thiadiazolo [3,2 -a] pyrimidine. In Firstwe hav synthesized 2-R5-oxo5-H6-EthylCarboxilate7-phenyl [1,3,4]thiadiazolo[3,2,-a]pyrimidine(3)  with Use2- R 5-amino  1,3,4- thiadiazole(1)andethyl 2- formyl 3- okco 3- phenyl propanoate(2). (Figure 1)

 

Figure 1. synthesis of 2-R7-phenyl 6- ethylcarboxylate 5-oxo 5-H 1,3,4-thiadiazolo [3,2- a]pyrimidine.  Click here to View Figure

 

And more2-R5-oxo5-H6-EthylCarboxilate7-phenyl [1,3,4]thiadiazolo[3,2,-a]pyrimidinereacted with  amin(4) until produced  2-R 5-oxo  5-H  6 -Carboxamid  7-phenyl  1,3,4-thiadiazolo-[3,2-a] pyrimidine(5).(Figure 2)

 

Figure 2.synthesof  2- R 5-oxo  5-H  6-Carboxamid 7-phenyl -1,3,4-thiadiazolo [3,2-a] pyrimidine. Click here to View Figure

 

In this regard synthes of  2-R 5-oxo  5-H  6-Carboxamid 7-phenyl -1,3,4-thiadiazolo [3,2-a] pyrimidinedo  with The aim of  2-R  5-oxo  5-H  6-ethylcarboxylate  7-phenyl  1 ,3,4-thiadiazolo [3,2-a] pyrimidine  and  amin in present  solvent C₂H₅OH.

Result and Discussion

 First, we tried synthesisof  2- R 5-oxo  5-H  6-Carboxamid 7-phenyl -1,3,4-thiadiazolo [3,2-a] pyrimidinewith 2-R  5-oxo  5-H  6-ethylcarboxylate  7-phenyl  1 ,3,4-thiadiazolo [3,2-a] pyrimidine  and amin in variousAlcohol. The reaction performed in the presence ofAlcohol shown in Table 1,

 

Table 1: Optimization of the reaction conditions Click here to View table

 

a Yields refer to isolated pure products.

this reaction doesnot take a in the present of catalyst .To show the generality and applicability of this procedure, we treated a wide variety of  2- R  5-oxo  5-H  6-ethylcarboxylate  7-phenyl  1 ,3,4- thiadiazolo [3,2-a] pyrimidine  and amin  in the presence of alcohol ethanol at 78^oC and obtained the desirable products in good to excellent yields (Table 2).

 

Table 2. synthesisof  2- R 5-oxo  5-H  6-Carboxamid 7-phenyl -1,3,4-thiadiazolo [3,2-a] pyrimidine with 2- R  5-oxo  5-H  6-ethylcarboxylate  7-phenyl  1 ,3,4- thiadiazolo [3,2-a] pyrimidine  and amina  Click here to View table

 

Experimental

A mixture of2-R  5-oxo  5-H  6-ethylcarboxylate  7-phenyl 1,3,4- thiadiazolo [3,2-a] pyrimidine (1 mmol), amin  (1 mmol) was stirred magnetically at 78^oC and the progress of the reaction was monitored by thin-layer chromatography (TLC). The reaction mixture was filtered .In all the cases, the product obtained after the usual work up gave satisfactory spectral data. 2-H 5-oxo  5-H  6-Carboxamid 7-phenyl -1,3,4-thiadiazolo [3,2-a] pyrimidine:¹H NMR (400 MHz, CDCl₃, δ ppm):6 (s, 2H, NH2) ;  7.14-7.30 (5H, Ph)7.50 (S, H).¹³C NMR (100 MHz, CDCl₃, δ ppm):118 (C), 126,4 (CH) , 126,4 (CH) ,128(CH), 128.7(CH), 128.7(CH), 136.9(C),140 (C),162,1(C), 163 (C), 168 (C), 172,6.

Conclusion

In conclusion, the alcohol has been employed  as a mild, and highly efficient solvent system for the convenient preparation of 2- R 5-oxo  5-H  6-Carboxamid 7-phenyl -1,3,4-thiadiazolo [3,2-a] pyrimidine in excellent yields from 2- R  5-oxo  5-H  6-ethylcarboxylate  7-phenyl  1 ,3,4- thiadiazolo [3,2-a] pyrimidine and amin. In addition low cost, recyclable solvent system. The advantages include low cost, mild reaction conditions and reactions carried out at room temperature with excellent yields.

Acknowledgement

The authors are thankful to the mazandran University Research Council for the partial support of this research and  thankful to DrHeshmatollahAlinezhad .

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