[Synthesis of thieno(3,3-d)- and -(3,4-d)pyrimidines by alternative ring closure reactions]

3-Acetylamino-substituted thiophene with cyano and carboxylic acid methylester group in 2- and 4-position react with primary amines to give thieno(3,2-d)- or thieno(3,4)-dpyrimidines. Furthermore thieno(3,4-d)-pyrimidines were prepared from non-acetylated thiophene derivatives. Some thienopyrimidines showed antiulcer antiallergic effects, respectively.