Synthesis of some novel heterocyclic compounds composed of thiadiazole, AZO and phenolic moieties and study of their antimicrobial property

Abstract

Heterocyclic compounds are highly essential to life as they play a vital role in the metabolism of all living cells, e. g., pyrimidines and purines are the bases of genetic material of DNA; the essential amino acids like pyroline,histidine and tryptophan; vitamin and co-enzyme precursors such as thiamine, riboflavin, pyridoxine, folic acid and biotin; the B12 and E families of vitamin. Heterocycles constitute a unique class of compounds, whether natural or man-made, show interesting biological activities and are often present as key components in the biological processes. Generally, the biological activities of these heterocycles are because of the presence of one or more basic heterocyclic moieties. In view of these, a series of novel heteronuclear thiadiazole derivatives containing phenol and azo moieties 1C-6C have been achieved by the cyclization of thiosemicarbazones 1B-6B with acetic anhydride. The structures of the newly synthesized compounds were characterized by chemical and spectroscopic methods such as IR, 1H NMR and 13C NMR. The synthesized compounds2C, 3C, 4C and 5C have been screened for their antimicrobial activity against Gram-positive bacteria Staphylococcus aureus(+), Gram- negative bacteria Bacillus subtilis (-), Escherichia coli (-), Pseudomonas aeruginosa (-), Salmonella typhimurium (-), Citrobacter freundii (-) and fungi Aspergillus niger, Tricodarmaharzianum. All the compounds showed moderate to good activity.

1. Synthesis of 1-[4-(4-Hydroxy-phenylazo)-phenyl]-ethanone 1A

1A

2. Synthesis of 2-(1-(4-((4-hydroxyphenyl)diazenyl)phenyl)ethylidene) hydrazinecarbothioamide 1B

O HO N N C + CH3

1-[4-(4-Hydroxy-phenylazo)-phenyl]-ethanone 1A

S

H2N C N H Ethanol 2 drops HCl

NH2

HO N N C

CH3 H

N N C

S

NH2

2-(1-(4-((4-hydroxyphenyl)diazenyl)phenyl) ethylidene)hydrazinecarbothioamide 1B

3. Synthesis of N-(4-acetyl-5-(4-((4-hydroxyphenyl)diazenyl)phenyl)-5-methyl-4,5-dihydro- 1,3,4-thiadiazol-2-yl)acetamide 1C

CH3

O

CH C

HO N N C H N N

C NH2 S

(AcO)2O 90°C

3 N N

S C N H

O

C CH3

(2E)-2-(1-(4-((4-hydroxyphenyl) N diazenyl)phenyl)ethylidene)hydrazinecarbothioamide N 1B

OH N-(4-acetyl-5-(4-((4-hydroxyphenyl)diazenyl)phenyl) -5-methyl-4,5-dihydro-1,3,4-thiadiazol-2-yl)acetamide 1C

The Diverse of my compound is

O

N O

C C N CH3 H

N N X= C6H5OH, pClC6H4OH, oClC6H4OH, X pCH3C6H4OH ,oCH3C6H4OH, C12H7OH

Antimicrobial activity

The synthesized compounds2C, 3C, 4C and 5C have been screened for their antimicrobial activity against Gram-positive bacteria Staphylococcus aureus(+), Gram-negative bacteria Bacillus subtilis (-), Escherichia coli (-), Pseudomonas aeruginosa (-), Salmonella typhimurium (-), Citrobacter freundii (-) and fungi Aspergillus niger, Tricodarmaharzianum. All the compounds showed moderate to good