Quinazolines from thioureas

The most unusual preparation of quinazolines from thioureas is that of Dziewonski et a/.,331 who fused /3-naphthylamine and thiourea to give two products, the structures of which they suggested were 190 and 191 on the basis of elemental analyses and hydrolysis of the reaction... 

The most unusual preparation of quinazolines from thioureas is that of Dziewohski et who fused j8-naphthylamine and thiourea to give... 

Other examples this type of quinazoline synthesis include the formation of the thione analog 752, by displacement of bromine from thiourea 751 <2003ARK(x)434>, and the imino compound 754, which could be formed by heating the guanidine derivative 753 in DMF, without the need for any added base <2005RJ01071>. 

Cyclohexanones have been employed in reactions with thioureas to give quinazolines with varying degrees of saturation. For example, octahydroquinazolinedithiones (182) have been prepared from cyclohexanone and symmetrical313 315 or unsymmetrical314 disubstituted... 

The chemical fixation of C02 in the presence of DBU or DBN led to l//-quinazoline-2,4-diones 115 <02T3155>, 5-acylated thiouracils 116a,b were obtained from pyridin-3- and 4-yl thioureas <02AJC287>, and dihydropyrimidines were obtained by an improved Biginelli reaction protocol... 

Quinazoline-2,4(l//,3//)-dithione is prepared from 2,4-dichloroquinazolinc on heating with sodium hydrogen sulfide or thiourea in alcohol in 44 and 77% yield, respectively. Analogously, quinazoline-2(l//)-thiones and quinazoline-4(3//)-thiones are obtained from the respective 2- and 4-chloroquinazolines. 

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