Synthesis of some pyridone derivatives

Chlorination of 6-aryl-3-cyano-2-pyridone-4-carboxylic acid (1) afforded the corresponding acid chloride (2) and the 2-chloro derivative (3). Esterification of (2) gave the corresponding esters (4a; b). Hydrazinolysis of (4a) afforded the respective pyridazinone derivative (5). Treatment of 6-aryl-2-chloro-3-cyano-4-pyridine carboxylic acid (3) with acetyl hydrazine, gave the triazinopyridine derivative (6), while treatment of 3 with sodium azide in DMF afforded the tetrazinopyridine derivative (7). Treatment of the N-acetyl derivative (1b) with thiosemicarbazide and/or hydroxylamine hydrochloride, yielded the correspoding semicarbazone and oxine derivatives (8) and (10), respectively. The reaction of 6-aryl-3-cyano-1,2-dihydro-2-thioxo-4-pyridinecarboxylic acid (1c) with ethylchloro acetate and/or thiourea yielded the mercapto ester derivative (11) and the corresponding pyrido [2,3-d] pyrimidine thione derivative (12). Condensation reaction of (1d) with anthranilic acid, afforded the quinazolone derivative (11). The reactivity of 11 towards hydrazine hydrate was investigated. The structural assignment of the new derivatives were based on IR, 1H NMR and mass data. Some of the new compounds were screened, in vitro, for antimicrobial activity and the results were encouraging.

Synthesis and antifungal activity of novel pyrano[2',3':4,5]thiazolo[2,3-b]quinazolines, pyrido[2',3':4,5]thiazolo[2,3-b]quinazolines and pyrazolo[2',3':4,5]thiazolo[2,3-b]quinazolines

The starting materials thiazolo[2,3-b]quinazolines (5a,b) were obtained in one pot synthesis by treating octahydroquinazoline (2) with chloroacetic acid and aromatic aldehydes. Thiazoloquinazoline (5) was reacted with CH2(CN)2/piperidine and CH2(CN)2/NaOH (CH3OH), to furnish pyrano[2',3':4,5]thiazolo[2,3-b]quinazolines (6a,b) and pyrido[2',3':4,5]thiazolo[2,3-b]quinazoline (7), respectively. Refluxing of 5a with NH2CSNH2/KOH and hydrazines in ethanol furnished the corresponding, [1,3]thiazino[4'5':4,5]thiazolo[2,3-b]quinazoline (10) and pyrazolo[3',4':4,5]thiazolo[2,3-b]quinazolines (11a,b), respectively. Antifungal activity was shown for some of the synthesized compounds.

Synthesis and evaluation of some new fluorinated hydroquinazoline derivatives as antifungal agents

The key intermediate octahydroquinazoline (1) was obtained in one pot synthesis by a modification of the Biginelli reaction. Compound 1 was allowed to react with phenacyl bromide and bromomalononitrile to furnish thiazolo[2,3-b]quinazoline 3 and 12, respectively. Interaction of compound 12 with formamide, formic acid and phenyl isothiocyanate yielded the corresponding pyrimidino[4',5':4.5]thiazolo[2,3-b] quinazolines 13, 14 and 17, respectively. The structure of the synthesized compounds were elucidated by elemental analyses and spectroscopic analyses. Some of the prepared compounds were tested for their antifungal activity in comparison with tioconazole as a reference fungicide.