Synthesis of bis-tren

The bis-tren ligand, 17, incorporates two triethylenetetramine sub-units, and forms a series of well-defined 2 1 (M2L) complexes with transition metal ions such as Cu(II), Ni(II) and Co(II). 

Treatment of the monochloro diethylene glycol 9 with dihydropyran yields the protected alcohol 10. Reaction of 2,2, 2 -triaminotriethylamine (tren) 11 with toluenesulfonyl chloride gives the tritoluenesulfonyl derivative 12. The pyranyl ether 10 may be condensed with the tris(sodium) salt of 12 leading to 13. Removal of the tetrahydropyranyl group is achieved in high yield under 

By this procedure the final compound 17 may be obtained in only seven steps with an overall yield of 12%, which is a significant improvement over the original lengthy route. 

Caution Carry out all procedures in a well-ventilated hood, and wear disposable vinyl or latex gloves and chemical-resistant safety goggles. 

Equip the round-bottomed flask with a stirrer and attach the condenser and the addition funnel. 

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