Synthesis of Pyrimido[5'',4'':5',6']pyrido[2',3':4,5]thieno[2,3-c]pyridazine and Pyridazino[4',3':4,5]thieno[3,2-b][1,8]naphthyridine, New Tetraheterocyclic Ring Systems
Synthesis of Pyrimido[5'',4'':5',6']pyrido[2',3':4,5]thieno[2,3-c]pyridazine and Pyridazino[4',3':4,5]thieno[3,2-b][1,8]naphthyridine, New Tetraheterocyclic Ring Systems