关键词: 合成, 多氮杂环烷烃, 1, 4, 7, 10-四氮杂环十二烷, 环化缩合

Abstract: Anew and simplified method for synthesis 1, 4, 7, 10-tetraazacyclododecane (cy-clen) has been proposed by two steps in this paper.The first step deals with cyclic condensa-tion of triethylenetetramine and diethyl oxalate in methanolic solution, giving the twelve-numbered cyclic oxamide, i.e., 1, 4, 7,10-tetraazacyclododecane-2, 3-dione.The pure prod-uct was obtained as a crystalline precipitate in 39% yield on addition of ethanol to the con-centrated solution of the reaction mixture.Subsequently, in the second step, the cyclic ox-amide was reduced in THFwith diborane produced in situ fr6m potassium borohydride andboron trifluoride etherate and extracted by CH₂Cl₂ from the basic aqueous solution of the sol-vent free residue, giving cyclen in 56% yield after removing the solvent.

Key words: Synthesis, Polyazacycloalkyl compound, 1,4,7,10-Tetraazacyclododecane, Cyclic condensation