Optically active tetraazamacrocycles analogous to cyclam

The syntheses of enantiopure tetraazamacrocycles analogous to cyclam, (S,S) -3, (R,R)-3 and (S,S,S,S)-4, have been carried out. NMR and semiempirical s tudies of 3 have revealed that this compound presents a rigid conformation with C-2 symmetry, which is stabilized by intramolecular bifurcated hydroge n bonds. Structural studies for macrocycle 4 have shown that the presence o f two cyclohexane rings of (S,S) configuration leads to the loss of the D-2 symmetry in solution, which is in agreement with the AMI calculated struct ure. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.