Open AccessStudies on quinazolines, part IV: Fused mesoionic heterocycles from 3‐amino‐2‐aryl‐4(3 H )‐quinazolinethiones
Author(s) -
Wasfy A. A. F.
Publication year - 2003
Publication title -
heteroatom chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.283
H-Index - 42
eISSN - 1098-1071
pISSN - 1042-7163
DOI - 10.1002/hc.10172
Subject(s) - malononitrile , chemistry , triethylamine , methiodide , mesoionic , phenyl isothiocyanate , medicinal chemistry , formamide , isothiocyanate , phenacyl bromide , aryl , isoxazole , thiazole , bromide , cyanoacetamide , quinazoline , organic chemistry , catalysis , alkyl
The 3‐amino‐4(3 H )‐quinazolinethiones 2a–c react with phenyl isothiocyanate in DMF, giving N,N‐disubstituted thioureas 3a–c . When 2a–c are treated with phenyl isothiocyanate in dry acetonitrile in the presence of triethylamine, the mesoionic compounds 4a–c are isolated. The methiodide 5a reacts with carbon nucleophiles such as malononitrile and/or ethyl cyanoacetate in the presence of triethylamine to give the corresponding 1,2,4‐triazoles 6a,b . On the other hand, compounds 2a–c react with CS 2 –K 2 CO 3 combination to furnish 1,3,4‐thiadiazolo[3,2‐c]‐4‐quinazolinium‐2‐mercaptides 7a–c . Treatment of the methiodide 8a with malononitrile in the presence of potassium t‐butoxide provides a mixture of 2‐[2‐(2‐nitrophenyl)‐3 H ‐quinazolin‐4‐ylidene]malononitrile 9 (24%) and 2‐amino‐5‐(2‐nirophenyl)pyrazolo[1,5‐c]quinazoline‐1‐carbonitrile 10 (40%). The reaction between Schiff bases 11 derived from 2a and phenacyl bromide yields 2‐benzoyl‐1,3,4‐thiadiazino[3,2‐c]quinazolin‐5‐ium bromide derivatives 12a,b . © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:581–586, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10172