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Macrocyclic aza analogue of the crown ether 12-crown-4. Cyclen compounds are capable of selectively binding cations and are used as a ligand with chemicals used in MRI contrast (as well ass other imaging) agents.

Cyclen (1,4,7,10-tetraazacyclododecane) is a macrocyclic aza analogue of the crown ether 12-crown-4. Cyclen compounds are capable of selectively binding cations and are used as a ligand with chemicals used in MRI contrast (as well ass other imaging) agents.

ChEBI: 1,4,7,10-tetraazacyclododecane is an azacycloalkane that is cyclododecane in which the carbon atoms at positions 1, 4, 7 and 10 are replaced by nitrogen atoms. It is a saturated organic heteromonocyclic parent, a crown amine and an azacycloalkane.

Journal of the American Chemical Society, 96, p. 2268, 1974 DOI: 10.1021/ja00814a056

Notclassified

Some syntheses exploit the Thorpe-Ingold effect to facilitate ring-formation. Illustrative is the reaction of the deprotonated tosylamides with ditosylates:
TsN(CH2CH2NTsNa)2 + TsN(CH2CH2OTs)2 → (TsNCH2CH2)4
The resulting macrocycle can be deprotected with strong acid. Base gives the tetramine.
High dilution conditions result in a low reaction rate penalty and this disadvantage is removed in an alternative procedure starting from triethylenetetraamine and dithiooxamide to a bisamidine – also a bis(imidazoline) – followed by reduction and ring expansion with DIBAL.

In one study cyclen is covalently bonded through a propylene molecular spacer to adenine and chelated with zinc diperchlorate. This complex is able to selectively bind uracil and uridine in a 1:2 ratio both through the adenine part and cyclen part of the molecule as evidenced by mass spectrometry.
wiki/Cyclen