"Yuji Miyazaki,Fujimaru Tanaka,Kenji Takeshita,Atsunori Mori","Synthetic Approach to N,N,N',N'-Tetrakis[(2-pyridylmethyl)ethylenediamine] (TPEN) Derivatives through Ruthenium-Catalyzed-[2+2+2]cycloaddition",,"HETEROCYCLES",,"Vol. 84","No. 1","pp. 527-535",2011,June