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2, 7-Diaminothieno[2, 3-d:5, 4-d]dipyrimidine-4, 5(3H, 6H)diones 4 were synthesized by a facile synthetic method, which includes bis-aza-Wittig reaction of bis-iminophosphorane 1with aromatic isocyanate to give bis-carbodiimide 2 and subsequent reaction o