A tandem decarboxylation and inverse electron-demand Diels–Alder reaction of amino-thiophenecarboxylic acids with 1,3,5-triazines

The scope of 1,3,5-triazine inverse electron-demand Diels–Alder (IDA) reactions was expanded to include aminothiophenecarboxylic acids as latent dienophiles. A series of 2-amino-3-thiophenecarboxylic acids (1a–d) and a 3-amino-2-thiophenecarboxylic acid (5) were introduced as productive dienophiles in IDA reactions with various 1,3,5-triazines (2a–e). This method is useful for the one-step synthesis of both thieno[2,3-d]pyrimidines and thieno[3,2-d]pyrimidines, which should complement existing methods.