New syntheses of 2-alkylthio-4-oxo-3,4-dihydroquinazolines, 2-alkylthioquinazolines, as well as their hetero analogues

N-Chloroacetylanthranilic acid ethyl ester reacts with potassium thiocyanat e in the presence of alcohol to give the (4-oxo-3,4-dihydroquinazolin-2-yl- sulfanyl)acetic acid ester (3a). In the presence of water or amines the ace tic acid derivative (3b) or the acetamide derivatives (3c,d) are obtained. 2-Amino-di-oxo-3,4-dihydroquinazolines (4) arise if vigorous reaction condi tions are employed. Analogously, N-chloroacetyl derivatives of 5-membered h eterocycles with enaminocarbonyl structure (5, 7, 9, 11, 13, 20, 23) react with potassium thiocyanate to yield thieno[2,3-d]-, thieno[3,2-d]-, imidazo [4,5-d]-, pyrrolo[3,2-d]-, and thiazolo[4,5-d]pyrimidines (6, 8, 10, 12, 14 , 21, 24). Quinazolines (18, 19) are formed from the reaction of 2-chloroac etylaminoacetophenone (16a) and 2-chloroacetylaminobenzophenone (16b) with potassium thiocyanate and subsequent treatment of the intermediates with. a mines.