The synthesis of ring‐expanded analogues of xanthine containing the imidazo[4,5‐e][1,4]diazepine ring system

The synthesis of 4,5,7,8‐tetrahydro‐6H‐imidazo[4,5‐e][1,4]diazepine‐5,8‐dione and its several 1‐ and 3‐alkyl (aralkyl) derivatives 2 has been reported. Mechanistic explorations of the final synthetic step as well as structural confirmation of a final product 2d by single‐crystal X‐ray diffraction analyses have also been presented.