Chiral Macrocyclic Aliphatic Oligoimines Derived from trans-1,2-Diaminocyclohexane

摘要

Aliphatic dialdehydes of rigid structures having a cyclohexane,a bicyclo[2.2.2]octane or a [7]triangulane skeleton,have been condensed with enantiomerically pure trans-1,2-diami-nocyclohexane to give [3 + 3] or [2 + 2] macrocyclization products.Unlike acyclic aliphatic imines,these macrocyclic oligoimines show enhanced stabilities and their structures in the crystals could be determined by X-ray diffraction analyses.The enantiomerically pure [7]triangulane dialdehyde showed remarkable diastereoselectivity in the condensation with the two enantiomers of trans-1,2-diaminocyclohexane:only one of the enantiomers gave a [2+2] macrocyclization product.Circular dichroism measurements combined with computational analysis show that the lowest energy electronic transition in these cyclic oligoimines is of n-pi* type.