Some reactions with ketene dithioacetals part I: synthesis of antimicrobial pyrazol

Pyrazolo[1,5-a]pyrimidines were synthesized via the reaction of ketene dithioacetals and 5-aminopyrazoles. The antibacterial and antifungal activities of some selected compounds are also reported.

Studies on aminopyrazoles: antibacterial activity of some novel pyrazol

Hydrazones 2a-d were prepared from diazotiazation of sulfanilamide or its derivatives followed by coupling with ethyl cyanoacetate. 3-Aminopyrazoles 3a-d were obtained by refluxing of 2a-d with hydrazine hydrate in ethanol. [Bis(-methylthio)methylene]malononitrile (4) was reacted with aminopyrazoles 3a-d in refluxing DMF containing triethylamine to yield the novel pyrazolo[1,5-a]pyrimidines 6a-d. The anilino derivatives 8a-h were obtained by fusion of compounds 6a-d with aromatic amines. When compounds 6a,c,d were subjected to the reaction with hydrazine hydrate, the hydrazino derivatives 9a-c were isolated. Also, the aminopyrazoles 3 were reacted with some electrophiles such as arylidenemalononitriles, ethoxymethylene malononitrile and ethyl ethoxymethylene cyanoacetate to yield the novel substituted pyrazolo[1,5-a]pyrimidines 13, 17 and 19, respectively. Structures of the new compounds were established by their elemental analyses and spectral data. Most of these compounds were also tested in vitro for their antibacterial activity against some gram positive and gram negative bacteria.

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.