Configurational isomerism of 2,5,5,7,9,12,12,14-octamethyl-1,4,8,11-tetraazacyclotetradecane and its compounds

The cyclic tetraamine 2,5,5,7,9,12,12,14-Octamethyl-1,4,8,11-tetraazacyclotetradecane can occur as six-diasterioisomers which are best characterised by the Cahn Ingold Prelog (CIP) priority rules. When coordinated, the nitrogen centres can occur in five configurations, resulting in 30 possible configurations. The configuration of the amines and their metal-ion compounds are unambiguously defined by the CIP configuration of the four carbon and four nitrogen chiral centres present. The chemistry of these cyclic tetraamines, and their metal-ion compounds is reviewed, with emphasis on structural studies, which permit unambiguous assignment of configuration. The literature reporting the preparations and properties of 2,5,5,7,9,12,12,14-octamethyl-1,4,8,11-tetraazacyclotetradecane and its compounds contains confusing and incorrect configuration assignments.

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► The preparation and isomerism of 2,5,5,7,9,12,12,14-octamethyl-1,4,8,11-tetraazacyclotetradecanes is reviewed.
► All reported structures of the amines and their metal-ion compounds are reviewed.
► The configurational isomerism revealed by X-ray diffraction studies of these compounds is reviewed.