Iminophosphorane 3 is a important intermediate in organic synthesis. A series of new 2-substituted tetrahydrobenzo[4′,5′]thieno[3′, 2′:5,6]pyrido[4,3-d]pyrimidin-4(3H)-ones 5 have been designed and synthesized via the tandem aza-Wittig reaction in 58-92% yields. Iminophosphorane 3 reacted with phenyl isocyanate (or 4-chlorophenyl isocyanate, 4-fluorophenyl isocyanate) to give carbodiimide 4, which was further treated with amines to cyclize in the presence of a catalytic amount of EtONa. The structures of compounds 5 have been confirmed by 1...
