Condensed Purines, I Synthesis of 6,7‐Dihydro‐1,3‐dimethylpyrimido[2,1‐f]purine‐2,4,8(1H,3H,9H)‐triones
The title compounds 2a–d and 4a–d are the sole products of the reaction between 8-aminotheophylline (1) or 8-(benzylamino)theophylline (3) and methyl acrylate, crotonate, methacrylate, and cinnamate in the presence of basic catalysts (Triton B or KOH). The structures of the compounds were determined by elemental analysis, spectral data, chemical transformations, and synthesis.