Mechanism of unusual formation of 3-(5-phenyl-3H-[1,2,4]dithiazol-3-yl)chromen-4-ones and 4-oxo-4H-chromene-3-carbothioic acid N-phenylamides and their antimicrobial evaluation.
6/6,7-Substituted 3-formylchromones (9a-e) react with 2 equivalents of 2-phenyl-4-dimethylamino-1-thia-3-azabuta-1,3-diene (10) or thiobenzamide (11) in refluxing toluene to furnish novel substituted 3-(5-phenyl-3H-[1,2,4]dithiazol-3-yl)chromen-4-ones (12a-e). However, reactions of substituted 2-anilino-3-formylchromones (15a-d) with thiobenzamide (11, 2 equivalents) in refluxing xylene furnish 4-oxo-4H-chromene-3-carbothioic acid N-phenylamide (17a-d) in high yields. A mechanistic rationalization of the conversion of 2-anilino-3-formylchromones (15a-d) to N-phenylamides (17a-d), and 3-formylchromones (9a-e) to the corresponding thioaldehydes, is proffered. All the compounds (12a-e, 17a-d) display very high antifungal and antibacterial activities against a number of strains. Dithiazole 12d exhibits a very high antifungal activity (MIC 5 microg/ml) against Geotrichum candidum, better than fluconazole (MIC 09 microg/ml) and also possesses good antibacterial activity (MIC 52 microg/ml) against Shigella flexneri.
Department of Pharmaceutical Sciences, Bio-Organic and Photochemistry Laboratory, Guru Nanak Dev University, Amritsar, Punjab, India.
Tilak
T
Raj
Richa Kaur
RK
Bhatia
Rakesh Kumar
RK
Sharma
Vivek
V
Gupta
Deepak
D
Sharma
Mohan Paul Singh
MP
Ishar
D000577:Amides / Q000737:chemistry* / Q000494:pharmacology*; D000890:Anti-Infective Agents / Q000737:chemistry* / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects; D002867:Chromones / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005658:Fungi / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D013057:Spectrum Analysis; D013329:Structure-Activity Relationship
D000577:Amides; D000890:Anti-Infective Agents; D002867:Chromones