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ABSTRACT:
Synthesis of novel ethyl 3-amino-5-(methylthio)-4-(5-substituted phenyloxazol-2-yl) thiophene-2-carboxylate derivatives from 3-amino-4-carbamoyl-5-(methylthio)thiophene-2-carboxylate was carried out by traditional as well as microwave irradiation green protocol. Ethyl 3-amino-5-(methylthio)-4-(5-substituted phenyloxazol-2-yl) thiophene-2-carboxylate derivatives were screened for antimicrobial screening against gram positive bacteria Staphylococcus aureus (ATCC 29737), gram negative bacteria Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853) and Candida albicans (MTCC 277), Aspergillus niger (MCIM 545) fungi.
KEYWORDS: Green synthesis, oxazole derivatives, thiophene-2-carboxylate, antimicrobial screening, microwave irradiation.
1. INTRODUCTION:
Synthesis of substituted oxazole derivatives is important because of their diverse range of biological activities in pharmaceutical areas1. Substituted oxazoles are important heterocycles that are biologically active molecules and synthetic bioactive molecules as well as in a number of organic building blocks including natural products, agrochemicals and pharmaceutical drugs2,3. Many of oxazole containing compounds like Martfragin A and Almazol D had been isolated from plants Martensa fragile and marine natural origins such as red algae4. Oxazole-containing compounds have been used as diabetes II treatment e.g. Aleglitazar, platelets aggregation inhibitor e.g. Ditazole, as part of tyrosine kinase inhibitor such as Mubritinib, and as COX-2 inhibitors such as Oxaprozin5. The wide range of biological activities of oxazoles includes antibiotics6, antiproliferative7, anti-inflammatory8, analgesic9, antibacterial, antifungal10, hypoglycaemic, antiproliferative, muscle relaxant11-12, HIV inhibitor activity13, RNA binding ligand activity14 and anti-tuberculosis15. Oxazole derivatives used as pesticides, fluorescent whitening agents, lubricants, dyes and pigments16-18. In addition, oxazole derivatives are useful synthetic intermediates and can be used as diversity scaffolds in combinatorial chemistry19 and also as peptidomimetics20. Thiophene substituted oxazole containing a-alkoxyacid derivatives were reported as dual PPARa/y agonists21. Thiophene substituted oxazole derivatives have proven their potency and selectivity as renal (A498), lung (NCI-H226), kidney (CAKI-1), and breast (MDA-MB-468, MCF7) carcinoma cell lines22. Thiophene containing oxazole and isooxazole compounds have been reported to exhibit anti-depressant, antianxiety activities, MAO inhibitors23. The biological activities of the thiophene based oxazole nucleus such anti-inflammatory, analgesic, antibacterial, antifungal anti-tuberculosis, muscle relaxant and HIV inhibitory properties have been explained in literature24.
2. MATERIALS AND METHODS:
All the chemicals and solvents have been purified by standard literature procedures and moisture was removed from the glass apparatus using CaCb drying tubes. The melting points determined in open capillary tubes with Gallenkamp melting point apparatus and are uncorrected. FT-IR spectra recorded on Bruker FTIR-TENSOR II spectrophotometer using...